Adobe After Effects

Linear Light, Gamma, and ACES

Imagine a digital 50% gray card. In 0–255 RGB values, it’s 127, 127, 127.

grayCard2021_009_A2_0001.jpg

On the RGB parade scope, the card is a perfect plateau at 50%.

Now imagine increasing the exposure of this scene by one stop. “Stops” of light are an exponential scale, meaning that subtracting one stop is cutting the quantity of light in half, and plus one stop is twice as much light. The light in our image is expressed in RGB pixel values, so let’s double the simulated light in this scene by doubling the values of the pixels.

Predictably, the 50% region has doubled to 100%. The perfectly-white regions are now overexposed to 200%, which looks the same as 100% in this non-HDR view. Our idealized pure-black patches remain unchanged.

But anyone who has moved a camera out of Auto mode knows that overexposing by one stop does not slam middle-gray into pure white. And anyone who has shopped for physical camera charts knows that you don’t buy “50% gray” cards. A middle-gray card at a camera store is an 18% gray card. So what’s up?

Yes, We’re Back to This Again

Back in 2009 (yikes) I tried to draw to a close my long history of writing about linear light and how it affects 3D rendering and compositing. But a funny thing has happened since then — along with many formerly niche Prolost subjects such as large sensors, 24 fps, and cinematic color, the topic of color management has become, and I can’t believe I’m writing this, popular?

That is thanks largely to ACES (Academy Color Encoding System), a color system aspiring to become the industry standard for managing for motion picture and television production. ACES builds on the ideas of performing certain kinds of creative work in a realistic model of light, and adds an output rendering that is so creatively friendly that a new generation of 3D artists have seized on it as a key part of generating realistic and/or pleasing imagery.

The other reason I’m back to this is that, in looking back at my numerous posts on color, gamma, and linear floating-point, they reflect a process of discovery, exploration, and advocacy — but they don’t coalesce into one convenient archive of information. Much of my unabashed championing of working in linear light was in the form of my tutorial series on eLin, which has long been taken down as eLin itself is now blessedly approaching a decade and a half of obsolescence.

This post is an attempt to consolidate, summarize, and modernize the Prolost take on film color management. Buckle up, it’s a long one.

Middle Management

An 18% gray card appears “middle gray” to our eyes because we humans do not perceive light linearly. Human vision has a “gamma” of sorts — a boosting curve that pumps up our perception of darkness and compresses highlights. I’ve heard this explained as a survival adaptation — it’s easier to see a predator or prey in the dark if we boost up the midtones on our monkey goggles.

Raw light values without gamma (asterisk asterisk asterisk).

An approximation of the roughly 2.5 gamma of human eyesight.

It’s complicated, but the non-linearity of our vision closely matches a few historical imaging methods, such as the densities of dyes on a piece of film, and the voltages in a CRT. So by a combination of happy coincidence and clever design, images that “look right” to our eye on modern displays have a gamma that aligns with the way our brains transform light into pictures.

For the purposes of this discussion, you don’t need to deeply understand all that (exhibit A: your dear author). All I want you to take away from this section is: linear images, where pixel math aligns well with real-world light phenomena, don’t look “right.” An 18% gray card looks middle-gray both in-person and on on our devices because of a shared/complimentary nonlinearity. Our eyesight has a gamma, and so do the images.

Why do we Gamma?

This convenient alignment actually makes it counter-intuitive to imagine working with real-world light values. If a 50%-bright thing on the display looks 50% of the way between black and white to our eyes, where’s the problem?

The problem comes when we want to model the real-wold behavior of light. In VFX, we do this in 3D rendering of course, but also in compositing. That obviously-wrong one-stop-over-is-blown-completely-out gray card example at the top? We call that “working in display-referred space,” and it’s how a lot of computer graphics were created in the early days. It wasn’t right, and it often didn’t look right.

Light Wins

In the mid-nineties I was part of a commercial shoot so ambitious that the post house sent their technical wizard/color scientist to the set. We were shooting on 35mm film, of course, and had an elaborate post session planned that was, if you can believe it, to be handled largely using a video switcher, not anything digital. Our animation crew was preparing to dangle some props in front of a greenscreen, and we asked him what we should do for the strings. Use fishing line? Paint them green? We were not anticipating having the ability to digitally paint out the strings (the Flame was just in beta back then!), so our decision here mattered a lot. He suggested matte-black thread. “With the smallest amount of motion, the strings will disappear against the exposure of the greenscreen.”

I and my fellow art school graduates nodded in agreement, but were secretly dubious. Surely black would be highly visible against bright green?

We shook off our skepticism and took his advice, and of course he was right. But I didn’t quite understand why. In my mind, a black string would stand out against a green background — and even if it was motion blurred, it would still be a very visible black blur.

The simulated blur above is what I thought the film would record, because I thought light and dark things were all equally-weighted in the motion-blur soup. I was thinking that light mixed in units that matched my perception.

But the linear-quality of light means that bright things occupy more of the number-space of the simple math we use to blur and layer digital images. So light “wins.” Here’s the same simulated model shot with simple sRGB gamma management:

In this example, the jet, the strings, and the background are converted from video gamma to linear using an sRGB curve, making them appear darker. Then the blur is performed. An inverse sRGB curve is applied to the result, brightening it back up. The pixels that aren’t mixed or blurred look identical (they “round trip,” as we say), but the blurred areas of the image now reflect the real-world phenomenon of light’s predominance over dark.

Another real-world example from my own history of discovery: In 2003 I snapped this photo of possibly the greatest movie poster ever printed, but accidentally shot a second exposure as I moved the camera away, capturing some streaky motion blur. Of course I tried blurring the sharp photo to match the streaks in the blurry one, but performing the blur in the native sRGB gamma of the camera JPEG resulted in a muddy blur, thanks to the perceptual mixing. But wrapping the synthetic blur in that sRGB → linear → and back pipeline makes it a near perfect match.

There’s one more experiment you can easily perform yourself to see light winning through your viewfinder: print a fine checkerboard, and photograph it both in and out of focus.

Blurred in display space, the checkerboard converges to a logical 50%. But in linear-light, the checkerboard smudges out to something brighter than 50% (0.5 ^(1/2.2) = 73%), just like the real photographed sample.

The history of my advocacy for a linear workflow has been full of examples like this. Motion blur, defocus blurs, simple compositing operations, 3D lighting and shading, combining 3D render passes or live-action exposures, even anti-aliasing of text, all look better, more organic, and more realistic when performed in gamma 1.0.

Linear Light & HDR are BFFs

In both the real world and in gamma-managed image processing, light overpowers dark. And so far we haven’t even broached the subject of HDR. When you add the ability to process pixel values greater than 1.0, light has even more opportunity to “win,” clobbering other elements in the mix.

Back to that Gray Card

To create a linear-light version of that gray card example, 2005-style, we apply an sRGB-to-linear conversion to the textures in the scene. We then perform the exposure calculations as above, but this math is now happening on linear-light pixels. The final step is to convert the results back to sRGB, using an linear-to-sRGB lookup. Without that lookup, the linear images look too dark on our display, like the deer example above.

With the sRGB lookup, the textures round-trip perfectly. 50% gray is still 50% gray. But the defocused background looks better, because highlights are “winning” in the boke calculations, just like real light does.

And when we start to increase exposure, we get a much more plausible sequence of increasingly-bright images:

Plausible — but maybe not the most pleasing. The sRGB curve is basically just a gamma curve, with a little straight-line portion at the base. If you have a camera that actually used this tone curve to map its linear sensor data to a JPEG, you would not love the results. They would appear flat and be prone to color artifacts as the channels clipped.

Here’s a real-world example for comparison — in-camera JPEGs shot with a Canon 5D Mark III:

The DSLR, even in sRGB JPEG mode, holds detail in the gray card at 3+ stops of overexposure in this case.

This is because when Canon says these JPEGs are “sRGB,” that defines their correct profile for display, but not necessarily their exact encoding. The encoding profile — the color adjustments and tone curve used to convert the linear raw sensor data to a viewable image — may be based on the sRGB curve, but it has some subjectivity baked into it; likely a little bit of s-curve contrast, and some highlight rolloff.

And that’s with the “Standard” Picture Profile, sRGB, and JPEG — likely the least dynamic range this camera would ever present. A raw file, log video, or even a less-contrasty profile could offer a significantly gentler highlight treatment.

If you work in linear-light, you’re doing things right — but if you want your results to look pleasing and/or photographed, an sRGB lookup alone is not good enough.

sRGB and Gamma Visualized

Before we skewer the sRGB “gamma” as a view transform, let’s examine what it actually is.

First, some terminology. Strictly-speaking, gamma is a power function. A gamma of 2.2 is the same as raising the pixel value, on a 0.0–1.0 scale, to the power of 1/2.2. But the term gamma has been broadened by some to include any kind of 1D tone curve applied to, or characteristic of, an image. Life is easier with this relaxed definition, so that’s how I use it.

Gamma Management is the term I use for a workflow that uses 1D lookups/conversions between formats. Magic Bullet Looks 5 and Supercomp 1.5 use Gamma Management rather than full color management.

You can absolutely gamma-manage your workflow using the pure gamma-2.2 and its inverse. But if your imagery is sRGB, it’s slightly more accurate to use the sRGB curve. The sRGB tone curve is a very close match to a pure gamma 2.2, but it has a little kink at the bottom to solve an old problem.

A pure gamma curve has a slope of 1.0 or 0.0 at its base, i.e. as the values in the image approach zero, the gamma curve approaches a flat line. This means that calculations on the darkest pixels in your image could be inaccurate, and those inaccuracies could compound through multiple steps of linearization and de-linearization.

sRGB has a steep, but not infinitely steep, linear slope at the very bottom, and then the rest of the curve uses a gamma of 2.4 squished to fit in the remaining range. The clever result is that the curve is smooth at the transition and robust through multiple generations of processing, even if the processing is not done in floating-point.

It’s easy to see how similar the gamma 2.2 and sRGB curves are by graphing them:

Tripping on Round Tripping

While the pure gamma curve and the sRGB curve are similar, two values for which they are identical are zero and 1.0. That’s fine, although there’s nothing special about 1.0 in either curve in the sense that the power function extends naturally through 1.0 and operates equally well on “overbrights,” or HDR values greater than one.

What is significant about these curves and their 0.0–1.0 range is that they round-trip cleanly, as I mentioned above. If you linearize with the inverse of these curves, do your thing, and then de-linearize, the pixels that didn’t get blended go right back to their original values. This is convenient, and for some motion-graphic applications, essential.

However, it’s the reason working linear is not enough.

Rendering a White Thing

Here’s a simple rendering to show what I mean. The first image is rendered using a simple Blinn-Phong shader in display-referred space, just like I used to do on my Amiga. The second is that same scene but with simple sRGB gamma management.

While the linear-workflow image above looks “better” within the limitations of this intentionally simple example, it doesn’t solve the clipping from the gamma-space version, in part because of this prioritization of round-tripping white.

No object is really “white” in the sense of reflecting 100% of the light that hits it. But we often work with synthetic images that have pure white in them (such as logos or text), and of course we expect those values to remain pure white even after round-tripping through an sRGB or gamma 2.2 linear workflow.

But at the same time, we expect our cameras to have that gentle roll-off. We expect a white object to photograph not as pure white, but as some reasonable white-ish shade that is not blown-out. In fact, from modern cameras, we expect enough dynamic range to capture a sun-lit shiny white car, for example, and shadow detail on a person’s face.

An unused take from Circle of Stone, directed by Mark Andrews and shot by me. As an experienced cinematographer, I would approach challenging lighting situations like this — with the bright white car surfaces and deep shadow detail — by pointing the camera and praying.

An unused take from Circle of Stone, directed by Mark Andrews and shot by me. As an experienced cinematographer, I would approach challenging lighting situations like this — with the bright white car surfaces and deep shadow detail — by pointing the camera and praying.

There’s a lot of detail in this shot, and a lot of challenging exposure. We can actually inspect the exposure values, because this shot was captured in log. This also means we can accurately convert it into linear-light values, and then render it with a simple sRGB curve:

Why would we do such a thing? The results, as you can see, are terrible. When you pass scene values to a simple sRGB lookup, with no other “display prep,” as cinematographer Steve Yedlin calls it, you get ugly results. Low dynamic range, clipped highlights, and posterized colors near areas of overexposure.

In fact, this synthetic example reminds me of early digital cameras that lacked the dynamic range to create a proper highlight rolloff. The overexposed waves in this Nikon CoolPix 995 photo from 2003 have the same harsh transition to white through posterized cyan as the sRGB-converted car above:

I paid $1,000 for this camera in the year 2000. This photo is 2048 x 1536. So, 1K for 2K in Y2K.

Rendering to linear scene values and then converting them to sRGB with the stock curve is ugly. If a modern camera did this, we’d laugh it back to 2003.

But this linear-to-sRGB (or gamma 2.2) final lookup is exactly how a lot of artists have been doing things “right” for years. We learn that we should work linear, so we dutifully convert our textures to gamma 1.0 and render to EXR. But if we use nothing more than the sRGB curve as our final lookup, we are treating our beautiful 3D rendered scenes as if shooting them with a first-generation digital point-and-shoot.

The industry’s standardization on this kind of simplistic linear workflow has left an aesthetic gap demanding to be filled.

Roll Out the Roll-off

When I was designing Magic Bullet Looks, and later Magic Bullet Colorista, I was aware of these issues. Magic Bullet Looks has always done its processing in linear floating-point values, which meant that it was possible to both manage and create HDR values, even back when no camera could generate them.

One thing we came up with to help render bright scenes in a more pleasing, film-like way was the Shoulder tool in Magic Bullet Looks.

Like many tools in Looks, Shoulder shows you exactly what it’s doing — in this case, smoothly mapping the brightest values in an image to asymptotically approach a maximum. The Highlight Rolloff control in Colorista V packs the same process into a single slider.

Let’s take a clear look at the effect Colorista’s Highlight Rolloff has on our example:

And on our simple rendered ball:

Highlight Rolloff is a nice, easy way to add a film-like “shoulder” to your HDR imagery. If you are using the gamma 2.2 “linear workflow” option in Cinema 4D, adding the (now built-in) Magic Bullet Looks Shoulder tool to your rendering is an easy way to create more pleasing highlights without radically changing the look of your renders. It’s the first step in upgrading our virtual cameras to match the expectations we’ve come to have of our real ones.

But can Highlight Rolloff alone solve all our rendering issues? No. And the easiest way to show that is by

Rendering a Blue Thing

Here’s that ball again, now textured blue.

Again, you can see the failings of the sRGB version (clipping and posterizing of highlights) are addressed, if not fully eliminated, by the Highlight Rolloff.

But what if we change the color of the light?

This does not look good. The very red light seems unable to illuminate the not-quite-pure blue of the billiard ball, instead tinting it a weird green.

If that feels wrong to you, but you can’t quite figure out why, let’s look at a real photo of a blue thing lit with red light:

The illuminated portions are purple, not green.

Highlight Rolloff, you are awesome, but you are not enough. The aesthetic shortcomings of sRGB view lookups are now joined by this bogus color rendering. There’s both an artistic and technical void here to be filled — and you guessed it, ACES is what’s come along to do so.

ACES: Come for the Technical, Stay (or Don’t) for the Subjective Aesthetic

What, exactly, is ACES? For the purposes of this article, here’s what I want you to know:

ACES is a color management system

ACES specifies a methodology for converting images among various color spaces. It is specifically designed for the motion picture industry.

ACES is a color space. Well, two.

ACES2065-1, or AP0, encompasses the entire CIE diagram. ACEScg, or AP1, is a carefully-chosen subset.

ACES defines two color gamuts, AP0 and AP1. AP1 is the “working” gamut, and like AdobeRGB and ProPhotoRGB, it is a wide-gamut color space, encompassing more colors than sRGB.

ACES includes color profiles for many popular cameras.

ACES ships with profiles for Canon, Sony, ARRI, Red, and more. This means it’s trivial to match the output from various cameras.

ACES includes an evolving set of final lookups for presentation.

For that final conversion from the linear-light, wide-gamut working space of AP1, ACES offers a handful of Output Display Transforms, or ODTs. The ones designed for SDR video output have built-in highlight rolloff, a subtle contrast curve, and special handling for bright, saturated colors.

ACES is a gentle prescription for a workflow.

The core ACES color profiles are designed to support the phases of a motion picture project:

  • ACEScg is the linear, AP1 color space designed for 3D rendering and compositing.

  • ACEScc is a log color space that also uses AP1 primaries. It is designed to be a universal space for color grading.

  • ACES2065-1 is intended to be a universal mastering color space for sharing and archiving finished projects. This is where that AP0 gamut comes into play — it encompass every color visible to the human eye.

The Technical

ACEScg is a linear-gamma working space of course, so it’s ideal for rendering and compositing. But that it is also a carefully-chosen wide-gamut color space is an equally important part of its design. Rendering in a wider-gamut space is one way to combat the green ball problem above.

The Subjective

Once you choose to work in a wide gamut, you then have to figure out how to map that image back to various output formats. As we have established, the simple sRGB transform (and its cousin, Rec. 709) is not good enough. The ACES team performed numerous tests and evaluations in designing their output transforms — and then revised the results several times. And they are still working on it. The look of these transforms is both studied and subjective, and while many people love the look, others have criticisms (especially around rendering of saturated colors). Remember above where I said that a simplistic linear workflow had left an aesthetic gap to be filled? Well these Output Display Transforms (OTF) are the primary way that ACES has stepped up to fill it. This explains why folks are so enthusiastic about the results it gives them, even if it is an ongoing field of development.

One of the most exuberant advocates of ACES for 3D rendering is Chad Ashley of Greyscalegorilla. Here’s a typical before/example from one of his excellent tutorials:

Image courtesy Grayscalegorilla. Watch the tutorial.

Image courtesy Grayscalegorilla. Watch the tutorial.

That is a pretty solid mic-drop of a comparison there. You can see how the ACES example has both the pleasing push of contrast we associate with film, as well as the smooth, languorous highlight rolloff. Colors are somehow both rich and restrained. The render looks real, but more importantly, it looks photographed.

Let’s do the same comparison with our gray card example from the top of the article:

To be clear, what makes the right side of the split an ACES render is a combination of transforming the textures into ACEScg linear, and then applying the ACES Rec. 709 ODT as a final view/encode transform. And while it looks fine, the contrast and highlight rolloff do make for an overall darker image. This is probably a much more realistic portrayal of the scene. The pure white patches on the card, which are far “whiter” than any real-world surface (fresh snow is about 85% reflective) render as light gray, and our 50% gray is coming in at 43%.

The “gamma,” or tone curve, of the ACES Rec. 709 ODT shown in magenta. It’s easy to see how it is darker overall than the sRGB curve (cyan).

Boosting ACES Rec. 709 by 0.36 EV causes 50% output to match sRGB. Note how similar the Colorista Highlight Rolloff variant of sRGB is to that boosted ACES curve.

To compensate for this, it looks like Chad Ashely rendered his scene a little brighter. The non-ACES version looks overexposed. Let’s boost the scene exposure so the gray card matches the sRGB example:

With gray matched, we get a better overall comparison. The contrast and soft highlights look nice. It’s a more photographed-looking version of our idealized scene.

What it is not, however, is a safely round-tripped version of our texture maps. Where the sRGB linear workflow mapped black back to black, 50% back to 50%, and impossible white right back to 1.0, this more realistic portrayal reminds us more of the real-world photography of the white cars. We see the bright white things as “white,” even though they are no longer pegging 255 on our displays.

What about our motion blur example?

Here ACES has let us down. By rendering the linearized image with the photographic contrast and highlight compression of the ODT, we’ve lost our seamless round-tripping. Our results are dark and dull. Because we knew what we expected our texture to look like at the end of the pipeline, the pleasing, subjective look of the ODT was not the right choice for this example.

This is meaningful for motion graphics, color grading, and compositing workflows. If “working in ACES” means changing the look of every pixel before you’ve even started to get creative, that’s going to surprise and dismay many artists.

For example, if Chad was trying to render his realistic vase in front of a client-supplied background plate, the same post-processing that he loved on his CG would mute out the photographed background.

Oh heck let’s look at that:

The sRGB rendering on the left, composited over this SDR iPhone video, has the typical sRGB artifacts covered above: clipped highlights and posterized colors near white. While the ACES rendering on the right solves these issues, it applies that same highlight compression to the SDR background, making it look dingy and dull.

If we want 3D rendered scenes to look photographed, do we have to let go of round tripping?

Oh Inverted Display Transform

Every ACES conversion requires at least an input color profile and an output.

ACES has a solution for this too. You’ll remember that ACEScg is our working space for rendering and compositing. It therefore is also our texture map color space, so in the example above, I’ve converted the billiard ball texture map and the SDR background plate from sRGB into ACEScg. I did this using the Open Color IO effect in After Effects, setting sRGB as the input, and ACEScg as the output. But critically, ACES also allows for using the contrasty, soft-highlights Output Display Transform as the “from” in this conversion. In other words, you can invert the output transform for images you want to cleanly round trip.

Using the Output Rec. 709 profile as the input, AKA inverting the ODT.

Given how complex the ACES Rec. 709 ODT is, I’m impressed that this is even possible. It’s a straightforward process to invert a 2D lookup, but the ACES ODT is a complex, 3D conversion, with special handling for saturated highlights. Inverting all this not only allows for round-tripping, it also has the interesting side effect of plausibly surmising HDR values from an SDR image.

Think about it this way: The photographed examples we’ve been discussing all have some kind of “shoulder” baked in. Inverting the shoulder-y ACES Rec. 709 ODT effectively un-shoulders photographed images, putting their compressed highlights back into a reasonable estimation of what scene values might have generated them.

Believe it or not, we used to have exactly this functionality in Magic Bullet Looks 1.0. We had Highlight Rolloff in the Output tab, and its inverse, “Highlight Roll-on” in the input tab! People were confused by this, so we ultimately removed it, but now we’ve replaced it with ubiquitous Input and Output tools.

Inverted ODT is not for Texture Maps

The inverted ODT allows us to round-trip video though ACES, but since it does so by creating HDR values, it’s not appropriate for texture maps representing diffuse reflectivity.

This is a big stumbling block for many artists dipping their toes into ACES. Their texture maps suddenly appear dark and dim, like the sRGB background above.

Step through the images below for a simulated example:

Crank Up Those Lights

You might have noticed something in the floating billiard ball example above: The ACES ODT so aggressively addressed the clipped highlights from the sRGB example that the resultant render appears a bit flat compared to the plate, which has lots of poppy highlights from the low sun.

When you invert the Rec. 709 ODT, the compliment to the rolloff curve causes 1.0 white to map to a very bright linear-light value: about 16.3 on a scale of zero to one. That sounds aggressive, but it represents about 6.5 stops of overexposure on an 18% gray card (0.18 × 2^6.5 = 16.3) — more dynamic range than the 5D JPEG example above, but right in line with the Sony s7SII log example with the white cars.

Another way of looking at it: It’s not a stretch to presume that the clouds in the iPhone plate are 6–7 stops brighter than the gray side of the dented car.

Artists working with a simple sRGB or gamma 2.2 “linear workflow” have been inadvertently training themselves to use conservative light values, because of the lack of highlight compression modeling high-end film or digital recording. If you lit your scene too bright, you’d get ugly highlights. But real scenes have big, broad dynamic ranges — which is part of why they’re so hard to photograph.

The virtual “sun” light that’s illuminating the rendered ball is set to 300% brightness, but the HDR values that light creates in the render get compressed down so much that I now want to push it more. Here’s the same scene with the light at 1,000% brightness).

If you’re not used to it, setting a light’s brightness to 1,000% feels strange — but in this example, that results in reflectance values of around 10.0, right in line with the HDR-ified highlights in the linearized background plate — as you can see in the underexposed version.

Astute readers will note that if inverting the ODT results in white being mapped to 16.3, then an ACEScg linear value of 16.3 is the darkest value that will be mapped to pure white in Rec. 709 — i.e. you need ACEScg scene values of greater than 16.3 to clip on SDR output.

Rendering to an ACES ODT encourages artists to create higher-dynamic-range HDR scenes, with brighter lights and more aggressive reflections. When you use brighter lights in a modern global-illumination render, you get more pronounced secondary bounces, for a more realistic overall appearance. ACES encourages artists to create CG scenes that better show off the power of modern CG pipelines, and, quite simply, look better, because they better model how real light works.

Even if that light is red, and the object is blue.

Back to Blue

Remember our blue billiard ball that went green when hit with a red light? ACES wants to help us with that too.

I’m not really this organized.

That’s sRGB with Highlight Rolloff on the left, and ACES on the right. Look how closely this matches the photographed example of a blue object under red light.

Our sRGB render failed in this case because of its limited color gamut. The saturated blue of our number two ball was near the edge of sRGB’s range of available colors. When we hit it with a strong red light, the results were out of gamut, so the closest approximation was returned.

ACES addresses this with the wider gamut of its AP1 color space. When you convert a texture from sRGB to ACES CG, you are both linearizing the gamma and also assigning new, broader color primaries. Visually, this results in a reduction in apparent saturation when viewing the raw pixels, so it’s easy to see how a once-saturated green color is no longer dangerously near the edge of the available range.

Adobe ProPhotoRGB has an even wider gamut than ACEScg.

But ACES AP1 is not tremendously larger than sRGB, especially at the blue corner. A common-use color space that does offer more range there is Adobe’s ProPhoto RGB. Just for fun, I tried rendering my blue ball in ProPhoto, with a hacked-together view LUT made from a 1D approximation of the ACES Rec. 709 ODT. As you can see, our red light can make the ball even more purple within the extra-wide gamut.

Sidebar: Adobe Camera Raw, and by extension Lightroom, reportedly does its processing in linear ProPhoto RGB, with an implicit s-curve for contrast and highlight rolloff. I’ve always admired Lightroom’s color rendering, and it seems it might be for some of the same reasons that folks like ACES.

So, if more gamut is better, why is ACES AP1 so conservative compared to other pre-existing color spaces? Why create yet another standard? At this point I have to explicitly call out this amazing page by Chris Brejon on ACES — specifically this section, where he has collected links and quotes about the decision-making behind the design of ACES AP1. The TL;DR is that a grossly oversized gamut, especially one that includes colors not visible to the human eye (that’s the part of the ProPhoto triangle that extends outside the CIE kidney-shape) can result in render artifacts like negative numbers and funky colors. He cites this thread on ACES Central forums, where Jim Houston also points out that the primaries were chosen to line up with colorist’s expectations of where R, G and B are on a color control surface.

ACES AP1 is a pragmatic color space designed for real-world use — a well-vetted blend of technical and artistic considerations. Nothing it does is expressly new (Adobe Camera Raw has been around since 2002), but ACES as a package is a practical standard for the film industry that, I will say once more, has risen to popularity largely because of gaps in mainstream workflows. Is it perfect for every use-case? No. Is it a boon to the film industry and the digital art community? Absolutely.

Color Grading in ACES

This is topic is most certainly worth its own post, if not series of posts, but here’s the short version: The same advantages and possible gotchas I’ve covered with rendering and compositing in ACES also apply to color correction.

  • Since ACES has color profiles for many popular cameras, it’s easy to unify footage from a variety of sources into one common color space for grading.

  • The ACEScc log color space is, in my experience, a creatively-friendly color space for grading. There’s also a tweaked version of it called ACEScct. The T is for “toe,” so this is the profile favored by Quentin Tarantino.

  • As with rendering, the ACES Output Transforms either jibe with your creative intent or don’t, especially around the presentation of overexposed, saturated colors. However, there are lots of ways to customize them.

  • Using the inverse Rec. 709 ODT to grade consumer video as if it was shot log is pretty darn cool. Check it out:

This short video demonstrates how ACES can elevate the basic color corrections on a video file. As I mentioned above, Magic Bullet Looks 5 has what we at Maxon/Red Giant call “Color Handling” rather than full color management — where we adjust gamma, but not the primaries. Why not full color management? The simple answer is that color management can be as confusing and off-putting as it can be helpful. The deeper answer is that, by using 1D LUTs, we can ensure perfect round-tripping. Which gets us to the biggest ACES gotcha of all:

The Inverse Rec. 709 ODT Workflow Does Not Round Trip Perfectly

In ACES 1.0.3, the magical inverse-Rec. 709 workflow does not cleanly round trip all colors. Some highly-saturated colors get stomped on in the process.

A cleanser version of the same issue in Resolve.

The wonderful Open Color IO After Effects plug-in from friend of Prolost (and eLin co-creator) Brendan Bolles uses LUT approximations for some transforms (because Open Color IO 1 does), so there’s bound to be some quantization. But even in Resolve, where ACES transforms are done in native CTL/DCTL code, these problems persist.

ACES 2.0 and OpenColorIO 2 may address these issues. So we’ve been conservative about fully adopting ACES within Magic Bullet, even as we’ve aimed for compatibility with it.

The same is true with Supercomp, although it’s relatively easy to composite in ACES with Supercomp even without native support. Just use the OCIO effect to convert your layers to ACEScg, and tag them as Linear in Supercomp. Don’t forget to set Supercomp’s output gamma to Linear as well. Then add an Adjustment Layer above the Supercomp layer with another OCIO effect converting ACEScg to Rec. 709, or the ODT of your choice.

Supercomp in ACES

All the advantages of color correcting in ACES apply to VFX compositing as well. The inverse ODT limitation could be an issue for folks working with SDR video sources. Most interesting though, is that the aggressive HDR-ification of video highlights (remember, values that were 1.0 in an sRGB conversion will be 16.3 in ACEScg) feeds directly into Supercomp’s floating-point rendering, making Light Wraps, glows, and other effects respond more intensely to highlights than you might be accustomed to. This can either be wonderful or unwieldily depending on the source material.

The white highlights on the water overpower the Light Wrap effect, but then check out this example:

Experimenting with ACES in After Effects

Screen Shot 2021-06-17 at 3.55.10 PM.png

Once you get the OCIO plug-in and the ACES profiles installed on your system, After Effects is a good place to experiment with ACES. After Effects even ships with an ACEScg ICC profile, which you can use as a project working space, and/or with the Color Profile Converter effect. I find this handy for converting HDR sources from sRGB to ACEScg, because Adobe’s ICC method does not clip, where the OCIO LUT-based operators sometimes do.

Things to Be Aware Of

Use sRGB to ACEScg for Textures

Or whatever the appropriate input color space is. Color texture maps shouldn’t try to represent more than 100% reflectivity, so don’t use the inverted ODT method for realistic diffuse surfaces.

Carefully Use Rec. 709 to ACEScg for Video Footage

The inverted-ODT-as-input method reconstructs plausible HDR values from an SDR source. Just beware of the aggressive mapping of near-white pixels into extreme HDR values, and the potential for saturated colors to get truncated.

Procedural Color Management is Better than Baking Conversions into Files

If you must bake out your ACEScg texture maps, remember that 8 bpc is not enough to store a linear-light, wide-gamut image. Use 16-bit TIFF, or EXR.

Color manage all color values, not just textures

A proper ACES color management solution includes managing the user-chosen colors for things like untextured objects and light sources. In my examples above, I had to rig up systems of converting my light colors into the color space I was rendering to, for proper apples-to-apples comparisons.

Don’t Try to Do ACES with LUTs

You can’t really emulate an ACES workflow using LUTs. Most LUTs are not designed to map HDR input, for example. It’s possible, but there are lots of gotchas. Native processing is better.

This Post References ACES 1.0.3

OCIO 2 is already released, as is ACES 1.3. ACES 2.0 is in development.

Coming in for a Landing

Remember the model-on-strings example way at the top? While the sRGB version showed how a linear workflow could emulate the real-world devouring of the strings on film, it only partially obscured the strings. My recollection was that our post-advisor was more resoundingly correct about the bright green background completely hiding the strings. By recreating the scene in ACES, I am finally, all these years later, able to simulate the way our black thread photographed in front of that greenscreen.

Cooler Management

I wish I could go back in time and tell 2004 Stu that this blog would survive long enough for color management to become cool. That, to me, is the most surprising thing about ACES — that it has captured the interest of technical artists and non-technical alike. ACES takes the concept of doing things “right” in linear light, and extends it to doing things beautifully. It’s transformed color gamuts and tone curves from the broccoli side-dish to an ice cream dessert.

ACES is not perfect for every use-case, but it is purpose-built for film and video work. Today, if you choose not to use ACES, it’s probably either because you haven’t tried it yet, or you already have your own complex, bespoke color pipeline.

To me, ACES is most significant as a common color language that I can use in my creative work and in my tool building. Expect to see more ACES in Red Giant and Maxon tools.

Resources

If you enjoyed this post, I can’t imagine you haven’t also pored over Chris Brejon’s entire glorious chapter on ACES. The highest compliment I can pay it is that I essentially rewrote it for this post.

ACES Central is the home of the canonical discussions on ACES, where you can be confused and intimidated right from the source.

There are many ACES tutorials online, and not all of them are good. But this one provides a compelling demo of ACES out-of-the-box ability to match different cameras into one unified color space for grading.

This article by Ben Baily is also quite good.

Here’s a brand-new tutorial on using ACES in Redshift.

And of course, you can grab my ACES presets for After Effects here:

And you know what? I have a feeling I’m still not done writing about this stuff.

Update 2023-01-08

Cinema 4D, Redshift, and Magic Bullet Looks now all feature built-in OCIO color management and ACES support.

Update 2023-02-07

And now so does After Effects.

Circle of Stone

TLDR; a short film I DP’ed is playing tons of festivals, and you can see it stream this Friday!

The Call to Action

In early 2017, my buddy Mark Andrews asked if I would be his cinematographer on a short film. Mark and I met at CalArts and have been making films together most of our lives, on and off. Most recently we collaborated on Brick & Steel, a fake-trailer-slash-birthday-gift for another CalArts buddy of ours.

Mark had been a story lead and a director at Pixar for years at that point, after a fruitful career in traditional animation. He’d won an Oscar for co-directing Brave with Brenda Chapman. He’d also been Andrew Stanton’s second-unit director on John Carter, and he wanted to direct a live-action short to show his range with actors and stunts. So, like, a slightly-grown-up version of the films we’ve been making since school.

I said no.

See, I don’t really consider myself a qualified cinematographer. I love shooting, and I’m happy to DP my own work sometimes, but the responsibility of Mark’s solo live-action directing debut felt like too much.

We were standing in my studio at that point. Mark looked around and asked, “So what’s all this gear for then?”

Damn.

Lining up a VFX shot under a tree while Mark snaps his own PR stills.

We shot in the foothills of the Sierra Nevada mountain range in Northern California. It was a well-run nine-day shoot, three days of which were devoted to fights and stunts, which were overseen by Allen Jo and Wayne Daglish. Wayne also nimbly operated a second camera. Eric Staudenmaier, who I’ve mentioned here before, was our drone operator. I got to exercise a lot of my gear on this shoot, including the StuCrane.

We shot on a pair of Sony a7SII mirrorless cameras, using exactly the settings everyone warns you against: sLog-3, s-Gammut3, recording those crunchy 8-bits right to camera cards.

Posting About Post

Using Supercomp to add muzzle flashes and smoke. The smoke is automatically backlit by the flashes thanks to Supercomp’s interactive effects.

If you’ve been watching my public appearances since then, Circle of Stone has found its way into some of my work. I used it in the first public demonstration of Supercomp, and it my tutorial for King Pin Tracker. I dove deep into a pair of shots on Adobe's stage at IBC 2019.

Color grading in Premiere using Magic Bullet Colorista.

I’ll have more to say about how we posted this film, but for now, let’s get to the point:

Film Festivals in COVID Times

Circle of Stone has been accepted into many film festivals, and has even won some awards. Film festivals, like all of us, are trying to figure out their place in a pandemic. I love this photo of our film playing in a parking lot in Portland.

As I felt was the case with NAB and SIGGRAPH, the loss of an in-person event can create an opportunity for an experience more people can share. Case in point: the Sin City Horror Fest, which is streaming online. Circle of Stone is part of its Shorts Block 5, which screens this Friday night (Oct. 23). So while I wish you could see it on the big screen, it’s pretty great that you can see it at all.

Find details on the Sin City Horror Fest stream here.

The best way to keep track of COS’s appearances is to follow @juniperroadfilms on Instagram.

Skate Warrior 1992, 1999, 2020

You May Have Seen This Image Before.

In The DV Rebel’s Guide, I used this still frame as an example of guerrilla filmmaking taken too far. Which may also be an apt description of the entire film from which it was taken.

In the summer of 1992, while I was home in Minnesota between terms at CalArts, I imposed upon the good will of my crew of childhood friends, asking them to appear in, crew for, and largely out-of-pocket fund, a film called Skate Warrior.

I did this without:

  • Money
  • A driver’s license
  • A camera, or any of my own filmmaking gear at all
  • Any good sense.

What I did have was time. Time to “write” a “script,” to endlessly storyboard, to plan and tinker and spray-paint toy plastic guns in my parent’s basement. I had the boundless energy and poor decision making of a kid only two year out of high school. Add to that a deep love of action movies, and some crazy ideas that a person could make one with next to no budget.

I storyboarded Skate Warrior on 3x5 notecards, which I kept in a binder that appears in the background of several shot in the film.

But in truth I did have one mighty resource: the community of my close friends and family. It simply never occurred to me, nor, seemingly, to them, that they should not drop everything to spend countless (often wee) hours schlepping me and my borrowed gear around, often risking life, limb, and legality, while I barked orders at them and rolled VHS tape. In my mind, my friends and family were all A-list actors, stunt performers, martial artists, and precision drivers — as well as dolly grips, production assistants, and caterers. And so they became, through and behind my lens. If you can give me credit for one thing in the making of this film, it’s taking greedy, exhaustive advantage of their generosity.

For example, it never crossed my mind that my brother Eric would not want to dress like a ninja and be thrown from a moving car. In fact, he very much did not want to. He said he would get hurt. I told him it would look great. Turned out we were both right.

ninja2.gif

The project hinged completely on one friend in particular: Steve DeCosse (credited as Steve Hershaw). The character of Skate Warrior was his creation; a notebook sketch during algebra class that we couldn’t stop talking about. Skate Warrior was also, of course, Steve himself — a self-created superhero for whom he was the alter-ego.

Steve was my action movie muse. He was a talented skater, which represented a small subset of his fearlessness in all things physical. He had a magnetism and charisma that I cherished as a friend, and knew from experience that I could capture on camera.

steveStand.gif

Steve was the reason Skate Warrior got made. And, tragically, he’s the reason you can see it today.

Steve DeCosse, 1972–2020

Steve circa 1990.

Steve circa 1990.

In May of 2020, Steve passed away unexpectedly. He is survived by his wife and three children. I had not seen him in over 17 years. It’s clear that his generosity and joyful spirit affected everyone who knew him the same way it did me.

I miss you buddy.

Speaking of Time Passing: COVID-19

Living under the strange timelessness of lockdown has inspired a lot of projects in my household, including a noble attempt by my wife to declutter our basement. Together, as we piled boxes for the dump, we unearthed a massive, beige hard drive enclosure that I suspected might contain the finished cut of Skate Warrior.

The “DataDock” system allowed SCSI drives to be “hot swappable,” an unimaginable luxury in 1997.

The “DataDock” system allowed SCSI drives to be “hot swappable,” an unimaginable luxury in 1997.

Me at CalArts in 1991. Traded in a gold for the platinum Bolex.

Learning to Cut

At CalArts, I made a couple of “real” films, shot and edited on 16mm film. But I and my cohort of filmmaking buddies rapidly gravitated to the immediacy and cost-effectiveness of making movies on tape. It’s almost impossible today to recall just how unthinkable this was back then. “Video” was a dirty word. But we were not trying to make beautiful films. We were trying to learn filmmaking, and we wanted to make our mistakes fast.

“I tell people making DV movies at home, use it for practice. Don’t even try to get it distributed unless it’s fucking fantastic. If not, just keep cranking them out. Get better; get better at storytelling. It allows you to do what I did when I started out, which is make a ton of movies for nothing. And you get so much better at it after a while, you can write them and direct them and you know the structure. You just need to learn how to do it and you learn by doing.”
— Robert Rodriguez in a 2013 Moviemaker interview

We would shoot on Hi-8, and edit in a linear tape-to-tape suite where it was nearly impossible to go back and correct mistakes. The only visual effects we could manage were either in-camera, or superimposed with by-hand sync via a genlocked Amiga 500 running Deluxe Paint III. This was the post methodology that I planned to use on Skate Warrior. But I never got around to the monumental task of editing over eight hours of footage into a finished film, so those camera originals traveled with me to the start of my film-industry career and adult life: my life-long dream job at Industrial Light & Magic.

There, as I learned the ways of the VFX pipeline created for Jurassic Park, I decided to take advantage of a friend’s access to ILM’s editorial AVID systems and learn non-linear editing as well. Forest Key, who would go on to co-found Puffin Designs and create the seminal Commotion rotoscoping software with ILM veteran Scott Squires, taught me the basics of editing on a computer, and the footage I digitized for practice was from those Skate Warrior tapes — which were already five years old.

The handguns of Skate Warrior were battery-powered toys from Laramie, the company that created Super Soakers. Pulling the trigger would cause the slide to ratchet in a photogenic way that I thought was essential to our plan, as I had no ability to digitally manipulate footage at the time. We sanded off the branding and spray-painted them silver and black. Batteries added weight, so we kept them in, meaning the actors were treated to a tinny gunfire sound effect when they fired.

Keeping VHS tapes in a cardboard box for five years, dragging them across the country from Minnesota to LA to Northern California — often in checked luggage or the back of a pickup truck — is not exactly a recipe for improving the already questionable image quality of half-inch magnetic tape. The footage looked just plain awful. As my AVID practice sessions morphed into long, late nights cutting the entirety of Skate Warrior, I was constantly questioning whether the effort was warranted. We were kids when we shot it, and it showed. This was going to be a terrible film.

If I had finished Skate Warrior in college, on tape, with the incredibly limited post tools available to me at the time, it would have been an impressive, “how the hell did you do that” accomplishment. Years later, lavishing this sophomoric albatross with the same VFX resources I was using on a Star Wars movie was only going to make people ask, “Why the hell did you do that?”

But the busier I am with my day job, the more intensely I pursue my side interests — and I was very busy indeed in those days. So during breaks from animating Naboo Starfighters, I picked away at the over 130 Skate Warrior VFX shots, using ElectricImage and After Effects, between 1997 and 1999.

I kept all the files on that single 5GB hard drive.

And Then I Was... Done?

In 1999, I “finished” the film, including a better score than it deserved by Mike Berkley, and sound design by Last Birthday Card composer David Levison. I somehow secured permission to use two songs from a ska band, because it was the ’90s. I even shot the “skate sequence” that I always envisioned for the opening of the film, in San Francisco, using my brand-new VX1000 DV camera.

Skate Warrior was done. I was about ready to render it.

And then I left ILM, and took my 5GB drive with me.

And put it in a box for 20 years.

Benjamin Warde, AKA my friend who owned a suit, as Agent Warde. Ben and I met in first grade, where we caused so much trouble together that our teacher made sure we were never in the same class for the rest of grade school.

Alex Bajuniemi as the sinister Lex with the dopest Jeep CJ7. Alex also supplied the VHS camera, the MG, the creepy basement, and occasional Swedish pancake breakfasts.

Bob Jens as “Bob.” Sadly Bob is also no longer with us — he died in a small aircraft crash around the time I was editing the film. Bob’s mottled-green Pontiac was affectionately known as “The Toad.”

Eric Bajuniemi, the one cast member who actually knew martial arts, as a henchman presumably named Eric. Gosh there sure are a lot of guns in this film.

Eric Maschwitz as the Ninja(s) who wear Chuck Taylors. Eric was and is a skilled fabricator, so he built most of the custom props for the film. Which were all guns.

Molly Feigal as Mol. The only experienced actor in the film, Molly provided me numerous opportunities to have no idea what to do with a female character.

 

One ⌘R in 1999 Could Have Saved Me a Lot of Trouble in 2020

I honestly can’t remember why I never rendered the final movie. I mastered it in After Effects 3.1, including some basic color corrections and all of the VFX shots, and as near as I can tell, that project was done, or in that awful, precarious state of 99% done. Why did I never just press ⌘R and render a final-ish version?

One plausible reason is that this render would have taken days — and back then, a beige Mac rendering After Effects was unavailable for any other tasks. Like making Star Wars.

The de-archived files as they appeared on my Mac in 1999. I apologize that I am obviously the reason Apple no longer allows visual customization of their desktop operating system.

Surely the primary reason though is the hardest to comprehend today: there would be little point in rendering the entire film back then, because there would be no way to play it back. That’s right, in 1999, specialty hardware was required to play back SD video. But I actually had that hardware: a Radius DV card. I should have left ILM with a copy of Skate Warrior on DV tape. But I did not.

Instead I left with it in pieces. A locked cut with no VFX shots, and series of dated folders full of poorly-named VFX renders, and one massive After Effects project that synced them all up.

These files are all from Mac OS 9, so they lack file extensions and other useful metadata. And many of them are in obsolete QuickTime codecs, including the two largest files that contained the locked edit as output from the Avid.

All of these superannuated files were locked on this grime-encrusted, decades-old hard drive, behind a 30-pin SCSI connector the size of a granola bar.

Imagine how many adapters it would take to attach this to a modern Mac.

Data Recovery

As time sailed on, the likelihood that I could find a functioning computer with a SCSI connector dwindled to zero. But after Steve’s passing, somehow the obvious alternative occurred to me — I could take the drive to a data recovery center. So that’s what I did, and they dissembled it right in front of me and looked up the serial number of the gigantic brick of a 5GB platter. “This was a very expensive drive when it was new.”

They easily recovered the data and emailed me a link a few days later. It took ten seconds to download. Nearly all of the QuickTime movie files were there.

And almost none of them would open on any computer I had access to.

Including the two main Avid output files — the reasons I’d gone to all this trouble. They would only display black pixels, no matter what I tried.

The Avid files would open in QuickTime Player 7, but would only show black.

QuickTime 7 would open some of the VFX shots, but not all. Good thing I hadn’t updated to macOS Catalina yet.

Digital Archeology

Skate Warrior was not quite done soaking up the generosity of those around me. I reached out to my wonderful community of fellow nerdy filmmakers, and eventually accepted an irrationally kind offer by Juan Salvo to help decode the footage. He was able to replace the header information in the QuickTime movies with something that would make them readable, and convert them to ProRes.

Now I had the finished cut and all of the individual VFX shots, and a 21-year-old After Effects project that held the key to realigning them. Here’s what that project looked like, running on my Mac in 1999:

I don’t miss this timeline window 1 bit.

After Effects 2020 will not open an AEP from before AEPs were called AEPs, but luckily for me, I have a friend who keeps a functioning museum of every version of After Effects that ever existed, because he was one of the original team that created CoSA After Effects 1.0. I sent him the project, and he sent me back a version I could open.

Then I proceeded to re-do most of the conforming work anyway, because I’m too lazy to do a small amount of boring work instead of a ton of mildly interesting work.

Remastering Skate Warrior in After Effects 2020.

Remastering Skate Warrior in After Effects 2020.

So at long last, in July of 2020, I rendered the final version of Skate Warrior.

And here it is.

“I’m sure you set out to make a good film. But what you wound up with is so much better than if you’d succeeded.”
— Benjamin Warde (Agent Warde)
 

You Should Not Watch This Movie.

Serioulsy, spare yourself. It’s bad. It’s boring, the dialogue is awful, and the plot makes not one lick of sense. It looks like a dog’s breakfast.

But it also contains the germ of many an idea that I still use in my filmmaking today. It was, along with The Last Birthday Card, the object model of The DV Rebel’s Guide. And there are a few good tricks in it.

car2jeep.gif

It contains this amazing stunt, which we never should have attempted. Please do not try this at home. These are not trained professionals.

jeep2car.gif

There’s also this mirror of that stunt, where Steve is “thrown” from the Jeep back to the car. At half-speed you can see the simple anatomy of the moment: An implausible pantomime of a throw, and a real and ill-advised stunt where Steve jumped from outside the roll bar of the CJ7, surprising me with a little slide across the hood for flair. Bridging the two shots is an insert of Steve leaping from the back seat, which we performed with the Jeep safely stationary. Someone did the job on the day of rocking the Jeep to give the shot life, and I added a digital streetlight blurring past in the background to sell the illusion of motion. Feel free to borrow this trick as often as you like, George Miller.

elevator.gif

The important shot I forgot to rip off.

Skate Warrior is full of “homages” to my then-favorite films, executed in that juvenile way that young filmmakers do, where they just mimic the scene without any insight, satire, or commentary. We humorlessly duplicated the violent gun shop scene from Terminator, and also shot-for-shot copied the moment in Die Hard where McClane is nearly crushed by the elevator. To film this, we inadvisably climbed on top of an actual moving elevator (in a location that not only did we not have permission to shoot in, but that we’d actually broken into). To make it look like the mechanism was anywhere near in danger of crushing Steve, I had to stand up from a crouch as I tilted the camera up, to add extra travel and get the metal block closer to the lens. Then, in the next shot, I added a glimpse of the mechanism in post. Being incompetent, I failed to copy the shot that would have actually sold this gag: Steve looking up at the camera pushing down on him, realizing he was in danger. Oops.

There’s a lot of double-cutting in this clip, inspired by studying Jackie Chan films.

There’s a lot of double-cutting in this clip, inspired by studying Jackie Chan films.

Another fun trick was this fight-on-a-high-ledge moment from the “climax” of the film. We shot this on an easily-accessible part of Northrop Auditorium in Minneapolis, where the ledge was only five or six feet off the ground. But for this moment of Steve’s legs dangling over a much higher drop, we relocated to the back of the building (which required Steve and Eric to shimmy around the entire building on said ledge).

I shot a POV of the drop years later in San Rafael, and digitally added Eric’s dropped weapon.

Colie Wertz, whom you might now know as a brilliant concept artist, doubling Eric for the fall. My plan was to stabilize out his vertical jump, which worked. What didn’t work was that Colie should have been wearing a white shirt to match Eric’s.

Dan Goldman, then R&D TD at ILM, now Giant Pulsing Brain at Adobe, doubling Steve’s silhouette for the final VFX shot. Everyone’s jeans looked like that back then. It was not a good decade for denim.

Eric’s character falls to his cinematic demise in this same angle, which I achieved by shooting an element of Rebel Mac Unit modeling wiz Colie Wertz jumping in place in front of a bluescreen that had been left standing in the ILM parking lot after an element shoot.

When the pickup drives over Eric, that’s me driving my Mazda over a curb, which I painted out.

When the pickup drives over Eric, that’s me driving my Mazda over a curb, which I painted out.

Lex fires the battery gun, with digitally-added muzzle flashes and shells as described in the DV Rebel’s Guide. The smoke in the final shot is practical, from a different toy gun that fired old-fashioned paper caps.

The skateboard was a hand-built miniature, which I mounted to a metal plate and pelted with a CO2 BB gun. Sit back there and say my hair ain’t luxurious.

We didn’t have a car mount, and didn’t think to improvise one. So any time you see a shot like this, it’s me riding on the hood, like an idiot.

Our version of “zirc hits” were illegal firecrackers that were frustratingly unpredictable. This one nearly deafened Ben, another one almost got us arrested.

To create these practical bullet hits, I fired BBs at the ground behind Steve and Ben. Ben did not like this idea, because he was afraid the BBs would ricochet off the ground and hit him. I told him it would look great. Turned out we were both right.

I slowed down Steve’s leap over the car (which he really did, effortlessly) and left Ben’s tumble real-time, to give Steve’s movement more of an anime-inspired timing.

Never imagining I’d have something like After Effects to help me assemble this film, I locked off the camera and added foil bullet hits to the car one at a time, thinking I’d rapidly edit them together. Using video tape. Like an animal.

The biggest effects moment in the film is where Skate Warrior’s skateboard transforms into a sword, as foretold in Steve’s high school notebook drawing and a ponderous flashback scene in the film. I modeled the skateboard and sword in Lightwave 3D and animated them in ElectricImage. I hand-animated the sparks in Commotion.

The other big VFX beat is when a hand-grenade blows up Bob’s car. This was a combination of a live-action plate and a Pyromania element from a CD-ROM.

My pre-digital plan for the car explosion was to blow up a miniature, which I actually did shoot on Super 8 film. I’ll let you know if I ever find that footage.

For the reverse of the explosion, we lit a piece of Bob’s car on fire and dropped it off a bridge. This is a true statement.

All of this and more I discuss in the most unrequested of all behind-the-scenes materials ever created: that’s right, the Skate Warrior Director’s Commentary:

Please also feel free to very much not watch this.

 

The Good Kind of Nostalgia?

There are too many names listed under “in memory of” at the end of this film. The song I chose for the credits, “Friend” by the Stubborn All-Stars, says “Those who live on, and those who may have passed; You’ve taught me one thing well: that nothing ever lasts.”

But I’m lucky enough to disagree. This crazy, stupid film exists. And so do an improbable number of the friendships that I abused to make it. Over the past 28 years, we’ve attended each other’s weddings, held each other’s babies, and mourned together as time took its toll.

Featured
Alex holding my three-month-old son as Eric M. and Molly look on.

Alex holding my three-month-old son as Eric M. and Molly look on.

Ben and Alex at Molly’s wedding, in a cave near where we filmed the second Jeep chase.

Ben and Alex at Molly’s wedding, in a cave near where we filmed the second Jeep chase.

My wife could be in the photo-bomb Olympics.

My wife could be in the photo-bomb Olympics.

Both Erics, at Eric B’s wedding, a short walk from where he dueled Steve on the ledge.

Both Erics, at Eric B’s wedding, a short walk from where he dueled Steve on the ledge.

Steve, me, and Alex, getting into the spirit of our 10-year high school reunion. Photo by Alex.

Steve, me, and Alex, getting into the spirit of our 10-year high school reunion. Photo by Alex.

Alex and Molly.

Alex and Molly.

My brother and my BFAM.

My brother and my BFAM.

Alex and me.

Alex and me.

As I grow older, I’m wary of the seductive alure of nostalgia. Looking back seems the opposite of moving forward. But in 2020, moving forward seems to take us into darker and darker places, so as a part of my ongoing commitment to questionable self-care, and inspired by a suggestion that Steve’s friends and family might like to see the cellar-aged fruits of our youthful labors, I allowed myself the indulgence of restoring this time capsule of my life and friendships from a formative period.

I’m thoroughly embarrassed by this film, and also immensely proud of it.

But mainly I’m just grateful to every single person who contributed to it.

Sorry it took so long to press ⌘R.

In 2009 I was reunited with the Bajuniemi family’s VHS camcorder that we used to film Skate Warrior. Photo by Alex Bajuniemi.