Color

iPhone ProRes Log in Peru and Taiwan

This is a blog post about a video, which is about new color-conversion LUTs for Apple Log footage from the iPhone 15 Pro and Pro Max (updated from my first set). The video is also a mini-travelogue of my recent trips to Taiwan and Peru. After my explainer video on Apple Log, this one dives a bit deeper into practical LUT workflows, and my state of mind about shooting digital-cinema-grade footage with a device I always have with me.

There’s a lot going on here.

Conflicted in Peru

Me relaxing on vacation. Photo by Forest Key.

I always have a moment when packing for a trip: Which camera to bring? Which lenses? I know I’m always happier when I pack less, like just a single prime lens. But sometimes FOMO gets me and I pack three zooms.

For my trip to Lima, I brought my Sony a7RIV with the uninspiring-but-compact Sony 35mm F2.8 prime. I lugged it around for a few days, but wasn’t really feeling it.

Meanwhile, my iPhone 15 Pro Max was calling to me with its ProRes Log video mode. “I’m 10-bit!” It would say. “Think of the fun you’ll have color grading me!”

I told my phone to shut up, and proceeded to shoot very little with it — or my Sony. Like a squirrel in the middle of the street, drawn in two different directions at once, I creatively froze.

Photography, for me, is made up of a lot of habits, and shooting iPhone video with aesthetic intent is just not yet baked into my travel muscle memory.

Made in Taiwan

A month later, I took a family trip to Taiwan, one of my favorite places in the world. I’d had some time to process my Peru deadlock, and decided to stop judging my own creative impulses, and let inspiration guide me in which camera I pulled out.

I wound up shooting a lot of video.

Me relaxing on vacation. Photo by Josh Locker.

I loved shooting ProRes Log in Taiwan with the iPhone 15 Pro Max. I’d occasionally reach for Blackmagic Camera, but I often just used the default camera app. I stuck my phone (with its crumbling case) out of taxi sunroofs and skyscraper windows, held it above teeming crowds and shoved it between chain-link fences. Seeing the broad dynamic range I was capturing in scenarios from noontime sun to neon-lit nights got me excited about grading the footage later.

It’s exactly the way I feel about shooting raw stills with my Sony, knowing that I’ll be able to go crazy on them in Lightroom. The photographing act is just half of the process.

Step through the frames below to see how color transforms a single shot from the video above:

LUTs, Looks, and Magic Bullets

There’s been a bit of a gold rush of people hawking creative LUTs that apply a particular “look” to iPhone Log footage. My day job is, in part, helping make color tools like Magic Bullet Looks, which can do so much more than any LUT. Creative LUTs are great, and by all means support the folks making them — but that’s not what my iPhone LUTs were or are.

The Prolost iPhone LUTs convert Apple Log to various other color spaces, and support three kinds of workflow:

Grade Under a Display Transform LUT

Apple Log is a totally decent color space to work in, so color correcting Apple Log can be as simple as applying Magic Bullet Colorista and choosing one of my Monitor & Grade LUTs. That’s what you see me doing in the video above. Colorista (set to Log mode) does its work on the native Apple Log pixels, and the LUT converts the result to look nice on video.

Many other systems work like this, including LumaFusion, which ships with Prolost Apple Log LUTs.

The key is color correcting under the LUT.

Bring Apple Log into an Existing Workflow

Color work is often done in an intermediate color space. This is usually some kind of wide-gamut, log format, such as Davinci Wide Gamut/Intermediate, or one of the ACES log spaces.

The Prolost ACES LUTs convert Apple Log to either ACEScc or ACEScct log, allowing you to grade your iPhone footage alongside any other professional camera, and output them all through the same pipeline.

Shooting Through a LUT

The Blackmagic Camera app allows you to load any LUTs you want and preview through them without baking them into your footage. With my LUTs, you can shoot with the same LUTs you grade under later, for a truly professional (no joke!) workflow.

The real stars of this update though are the FC LUTs. They add an informative False Color overlay to the Shoot/Grade LUTs, making sure you always nail your exposure. Watch the video to see them in action. I already can’t imagine shooting without them.

These LUTs work well in Blackmagic Camera or even on an external HDMI monitor.

Adjusting exposure with a variable ND filter until the 18% gray card lights up yellow, for perfect exposure. PL-HERO-FC LUT in Blackmagic Camera.

Gathering Resolve

I’ve never edited a whole actual thing in Resolve before.

As if this video wasn’t enough work already (I shot the A-roll in mid-December), I decided to use it as a personal test-case for creative editorial in DaVinci Resolve. It’s the ACES LUTs that allowed me to incorporate Magic Bullet Looks into my Resolve color workflow.

Maxon just shipped a really nice update to Magic Bullet Looks, with simplified color management made possible by more and more apps we support doing darn fine color management at the timeline level.

So in Resolve, I can use my LUT to convert Apple Log to ACEScc, and then apply Magic Bullet Looks, which can now be set to work in ACEScc with a single click.

The new streamlined color options in Magic Bullet Looks. Choose Custom to get the full manual control.

I can sneak additional Resolve corrector nodes between those two for local corrections. Resolve is great at this, and Looks is great at creative look development, so this is a match made in heaven.

A little face lift.

Then, at the end, I use an ACES Transform node to convert to Rec. 709 video.

Get to the chopper.

An expert Resolve user could replace my LUTs with Resolve’s built-in Color Space Transform nodes, but the LUTs make this process easier and more reliable.

Gear Inspires

Every photographer knows the feeling of lusting after new gear. We know it so well that we remind ourselves constantly that “next camera syndrome” is debilitating, and that “most cameras are better than most photographers.” Gear is not the answer. Go shoot.

There is, however, a counterpoint to these truths: As shooters, we take inspiration where we can get it. And sometimes a new technique, a new locale, or even, yes, a new bit of kit is what provides it.

The key is to listen for that inspiration, and don’t judge it.

Even if it’s coming from your phone.

Jiufen village, Taiwan. Two a7RIV shots stitched in Lightroom.

Log is the “Pro” in iPhone 15 Pro

And I’ve got some free LUTs for you.

The iPhone 15 Pro and Pro Max feature log video recording. This is a big deal, but there’s already some confusion about it. Where consumer devices and pro video overlap, that’s where the Prolost Signal gleams brightest in the night sky. So let’s get to work.

First, what exactly is log? It’s short for logarithmic encoding, which is a math thing, but what does it mean to videographers?

It really boils down to two things: Log is flat, and log is known.

Flat is Good, and Log is the Best Flat

Standard iPhone video is designed to look good. A very specific kind of good that comes from lots of contrast, punchy, saturated colors, and ample detail in both highlights and shadows.

Log video looks flat. All the dynamic range and detail are there, but gone is that candy-coated punch. To make log footage look right, you have to color manage it in some way, often with a Look-Up Table, or “LUT.”

A LUT is just a color adjustment baked into a single file. Some LUTs add creative looks, others are more utilitarian, converting images from one color space to another — like from log to video.

If all we’re going to do with log footage is apply a LUT to make it look normal, what’s the big deal? Why add this extra step?

The power log gives us lies within that extra step, because:

  1. You pick the LUT! So log footage can look however you want. Sure, you can apply LUTs or color grading to regular iPhone footage, but the problem is it already has its own very punchy look baked in. With log you can pick the look that works for you, and even more importantly...
  2. You can color grade under the LUT. So you can adjust the color of the footage in a natural and organic way.
  3. And this workflow matches what you’re doing with your digital cinema camera already, so you can color-manage this footage right into a timeline with your Canon, Sony, Arri, or whatever else you’ve got.

Log footage from iPhone 15 Pro Max with various LUTs and looks applied. Model: Karen Lum (@womanlystateofmind)

You Didn’t Explain What Log is Though

But what is the log of log? What does this math concept mean to me?

The essence of log (in its purest form) is that every stop of light gets the same amount of data. Ten-bit footage holds 1,024 shades of gray. To represent 12 stops of light values (or dynamic range), that means each stop gets about 85 shades of gray.

This means highlights and shadows all have detail that you can access for basic color corrections like exposure and white balance. You can recover some shadow and highlight detail, and make substantial color adjustments that look natural.

In this hypothetical example, we spread 12 stops of light evenly over 1,024 shades of gray.

In Log We Offset

It also means that these basic color adjustments are dead simple to perform. Since each stop (in our semi-made-up example) is 85 shades of gray, adding 85 to the value of each RGB pixel is the same as increasing the exposure by one stop.

We call this adding and subtracting Offset, and Davinci Resolve has a whole color wheel devoted to it. In Magic Bullet Looks, the Global color wheel in the 4-Way Color Tool does an offset adjustment in ACES log, even if your source footage isn’t log. With log footage, Offset is the most natural way to correct, tint, or re-expose your footage.

These kinds of simple corrections look terrible when done after the LUT, or to video-space footage, but when you do them to the log pixels before the LUT, the results look so natural, it almost appears that they happened in-camera. This makes it much easier to achieve consistent color across shots, as they all get the same last step. This is why it’s such a common workflow to put Magic Bullet Looks, for example, in an adjustment layer over all the shots in a sequence.

Sun Dog

Log corrections look natural in part because the simple color-grading math lines up with how light works. They also look great because of the available dynamic range.

If I try to recover some of the detail in my dog’s sun-lit fur, this iPhone 12 footage rapidly falls apart. The iPhone added contrast, and in doing so smooshed the white values into a uniform overexposed patch. Nearby colors are posterized, and the clipped highlights give the shot away as consumer video.

Source: Kodak

But with this iPhone 15 Pro Max footage shot in Apple Log, I can recover all the detail — or just let it overexpose gracefully into this ACES output transform, for a smooth, film-like look. This soft highlight rolloff in the log-to-video conversion is called a “shoulder” in film, describing the upper part of the classic s-curve. A nice shoulder for your highlights is a big part of what makes footage look “pro” — especially when your grading happens underneath it.

Because log footage uses the same amount of data for every stop, it’s not the most efficient way to store an image. So log is best when it’s at a high bit depth and data rate. Apple Log is only available when recording in ProRes, which is typically 10 bits-per-channel. Apple added ProRes with the iPhone 13, but without log it wasn’t very “pro,” and I almost never used it. The baked-in look made grading difficult, so there was no reason to take on the burden of the massive files.

Heavy is the ProRes, Dangly is the Drive

Apple and Samsung, sitting in a tree.

Yes, massive. 4K ProRes files are big, and recording them to your phone can create some weird workflow challenges. Apple shocked us all by addressing this head-on: The iPhone 15 line charges via USB-C instead of Lightning, and this standard USB port can do a lot. When you connect a USB-C drive, your ProRes Log video automatically gets recorded there instead of to the phone’s photo library.

Recording this way also unlocks 4K 60fps recording in Apple’s Camera app, enabling some gorgeous slow motion effects when played back at 24 fps.

In just two years, Apple has gone from refusing to sell you a pro laptop with an SD card reader to making a camera that records to external media. We’ll all be looking for iPhone rigs with places to strap these little drives.

Drive 1, Drive 2

Log is Half Baked

In this unprocessed log clip, the purple light reflections appear over-saturated.

With its high bit depth and dynamic range, log footage has many of the benefits of raw. But Apple Log is not raw, and not even “straight off the sensor.” It’s still heavily processed — denoised, tone-mapped, and color adjusted. You can see this big time if you shoot bright, colorful lights. Even though Apple has turned their sharpening and tone mapping way down for Apple Log, there’s still some of that telltale overdriving of super-bright, super-saturated colors.

It’s also important to note that log does not mean you’ll never overexpose. It’s still an iPhone with a tiny sensor, so don’t expect the dynamic range of an Arri Alexa or a Sony Venice.

Blackmagic Camera App

The other way Apple doesn’t quite live up to the “pro” promise of log is by not offering much manual control in their camera app — and that’s totally fine. Because all the control you could want is found in the wonderful new Blackmagic Camera app. It’s a free download, presumably meant as a gateway drug to Blackmagic’s paid products and services. It’s a terrific app with a gorgeous UI and pro features like a live histogram, display LUTs, HDMI out via USB-C, and choices of different ProRes formats.

Note that the shutter speed is set in degrees! What a time to be alive.

VFX Log

The flatness of log gives you the power to make it your own in the grade. The other huge advantage of log is that it is known, meaning it’s possible to convert it to and from various color spaces accurately. This is a huge advantage for VFX artists and colorists alike. Colorists can convert Apple Log to whatever color space they like to work in, and accurately incorporate iPhone footage into any color timeline. VFX artists can convert their log footage to scene-refererred linear and create accurate composites that include color-matched 3D renders.

In this example, I converted the footage to EXR and camera-mapped it onto simple geometry in Cinema 4D. In Redshift, those HDR pixel values cast light and reflections onto the 3D model, doing 90% of my lighting for me:

ACES Compatible?

Apple’s log format being known is all it takes for compatibility with ACES, the Academy of Motion Picture Arts and Sciences color management system. But it’s important to note that Apple Log does not match any pre-existing ACES format.

The log curve is Apple’s own, which they’ve documented, and it’s already available in DaVinci Resolve. In the CST node, choose Apple Log for the Input Gamma, but choose Rec. 2020 for the Input Color Space, because Apple Log uses the Rec. 2020 primaries.

With these as your inputs, you can either convert to Rec. 709 video, or to an ACES format like ACEScc — which is also log, but a different log.

Remember when I said log uses the same amount of data for each stop? That’s not entirely true with Apple Log. The darker stops are compressed a bit, to control noise. If you’re familiar with ACES, this makes Apple Log more similar to ACEScct than to ACEScc. Many colorists prefer working with ACEScct because of the way it handles shadows, so Apple is in good company here.

Along with documenting their unique transfer function, Apple has supplied a LUT for converting from Apple Log to Rec. 709 video. Apple’s LUT is very rich in contrast and saturation. This is useful if your goal is to match the look of non-log iPhone footage, but I found it too colorful for some applications, so I created my own LUTs that roll highlight colors off more naturally.

While Resolve and Final Cut Pro both offer built-in support for Apple Log, some other tools don’t yet. So I also made LUTs for converting Apple Log to ACEScc and ACEScct — the ACES log formats designed for creative color work. With these LUTs, you can incorporate Apple Log footage into an existing ACES workflow without losing any color fidelity.

To some, true ACES compatibility would require Apple Log’s inclusion in widely-distributed ACES OCIO configs. Until that happens, Apple Log is ACES-compatible as long as you have a color-space conversion bridge — something like either the CST node in Resolve or the Prolost Apple Log LUTs, available below as a free download.

Magic Bullet Magic

With this workflow, I was able to run some iPhone 15 Pro Max footage through the ACES-compatible Magic Bullet Looks, using our new Diffusion filters modeled after real-world filters from Tiffen and others. Along with some basic grading, I also added some film halation and grain. The results have a rich, cinematic look that in no way betrays that it was shot on a consumer phone.

Rebel Without an Excuse

The argument about whether it makes any sense to shoot professional video on a consumer device dates back to before my book, The DV Rebel’s Guide. I love small, accessible cameras that allow us to shoot unnoticed in public places, but for years I discouraged the use of phones for this, because the ability to control and author the image just wasn’t there.

Now that the iPhone can shoot log, is the best camera the one you literally always have with you, or, you know, an actual good camera? The iPhone 15 Pro Max is going to tempt you to shoot real stuff with your telephone, and for the first time ever, I’ll be right there with you, thanks to log.