So, why ACES?

(André Rodrigues) #1

So, as far I could understand, ACES is kind of a “master codec” which I should transcode all my material to ACES and start to work with it.

Ok, but where is the advantage? As far I could understand, the advantage is you can recover all the color and dynamic range information is that??? But recover HOW?

Because first I was thinking you need the original files with ACES format to recover, which doesn’t make any sense, because with the original files I can do it with any codec/format. If I have the original, so I have everything I need, doesn’t matter the format or codec. So?!

Than I was thinking maybe I can recover AFTER the conversion? Is that? For example: I can use ACES to edit my material, export in h.264 and send to someone. If this person want change something in this archive he will have the same Dynamic Range I had with the original file?! If is that, OK that’s a miracle and it’s excelent.

So… The resume is: I’m totally lost here…

(André Rodrigues) #2

So, no one can clarify it to me?

(Steve Tobenkin) #3

Hi Andre

I think it’s just the weekend and people are out enjoying the great weather (here in LA at least!)

I’ll take a try at explaining and hopefully some other more technical types can chime in.

The idea behind ACES is that you take your original files (camera raw, film scan, etc) into the ACES color space, which is a very large colorspace: 16bit floating point EXRs, effectively bigger than your eye can see. That way you are preserving all the color fidelity in your original files. You then work in ACES and only export into smaller color spaces (709, or others) as a deliverable for different distribution platforms.

ACES will preserve the color fidelity of your original files but doesn’t “recover” any fidelity per se, i.e. if your highlights are clipped and color is 8Bit, it doesn’t create new color information, any more than encoding a 4:2:0 HDV file into ProRes 4:2:2 didn’t add info, it just makes it able to be combined with other similar materials.

There are some significant benefits of working in ACES, which you may see, depending on what type of work you do. If it’s mostly REC709 TV work or you’re shooting in 8bit, compressed cameras material, it may not be for you, although many boutique color facilities have elected to standardize on ACES because it’s sophisticated color science, and a known, recognized standard they can employ without having to have a color scientist design a color pipeline.

Some Benefits of ACES:

  1. Color matching materials from different cameras, inputs becomes significantly easier when you use ACES. It doesn’t make a GoPro look like an Alexa, but it does allow you to work with the two much easier in one timeline
  2. it allows you to trade files with other facilities, etc. and assuming that both parties have calibrated their monitors and working environment, you can have confidence that you are seeing colors accurately. This helps tremendously for VFX facilities who get clips from an edit…they can work to the clip color with confidence and not change the color which then causes problems when those modified color clips are re-inserted back into the master cut
  3. it is a defined set of standards with metadata that explains what you’re looking at and the environment (color temp for example) that it’s intended to be viewed in. This means that a master and archive can be created that can be revisited even if the original creators are not available to explain.

ACES is resolution independent, it’s concerned with color depth, white point, etc. My understanding is that if you reencode your ACES material into H.264 you will affect the look not necessarily because of the resolution change but because of the bit rate reduction (I believe most H264 is 8 bit, there is 10 bit, but no 16bit to my knowledge).

So ACES doesn’t change the laws of physics but it does allow you to have more control and confidence in your color pipeline if you use it as recommended.

Hope this begins to answer your questions.

(André Rodrigues) #4

Excelent and clear answer! Thanks Steve!