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What is AP's WORKING color space?


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Hello to all.

Color-managed workflow on a Windows 10 home and in Affinity Photo (AP) Version 2.5.5, if that matters.

Here is a good primer for what I'm about to ask, and especially this part of that article on WORKING profiles, and this one on OUTPUT profiles. I am speaking of developing images from the raw file, but this may extend out to simple modifications on a jpeg as well.

TLDR: What is the innate WORKING color space used by Affinity Photo? I am mostly curious about the Develop and Photo personas.

I'm asking because this is not indicated anywhere in AP, as far as I can determine:

  • AP's help on color management is not clear on this,
  • the Color tab on the Settings menu lets you assign profiles but does not indicate if those are working or output color spaces,
  • and the only other place I know of where a color profile can be assigned is in the Develop Persona, where the Profiles tab only lets you assign an "Output Profile."

In the "good primer" link above, it is explained that in RawTherapee, the working color space is ProPhoto, and that it is the color management process that is going to adapt what is seen on the monitor to this latter's gamut. The output profile will be attached to the file that is exported: if the output profile is set to sRGB, that will be embedded in the exported image. Now, if, like me, you're on a color-managed system with a monitor only capable of showing sRGB, you've been looking at only the sRGB color space all along. The working profile is an under-the-hood thing, but that larger color space under the hood lets you develop the raw image with greater flexibility, pushing colors in to or out of the monitor's gamut as needed.

For what it's worth, this Digital Photography article says that Lightroom works the same way, and even doesn't give you a choice about it.

So, my questions:

  • is Affinity Photo, like Lightroom and RawTherapee, using ProPhoto ("ROMM RGB" in Affinity-speak), as the 'under-the-hood' working color space? 
  • If not, will selecting "ROMM RGB: ISO 22028-2:2013 at Settings > Color > RGB color profile make it do so, OR, is that setting only for the output profile? Of course, if it is, setting ROMM there would be a very bad thing to do.
  • What does "Output profile" mean on the Profiles tab in the Develop Persona? Is it just preparing AP to assign X (sRGB, Adobe RGB...) profile to the image at export, OR, is it converting the working color space to X profile when it develops the image toward the Photo Persona? Is so, that would mean that once in the Photo Persona, you are now working in a constrained color space. In this scenario, would it be correct to set the ROMM space there, before developing to the Photo Persona? 

Hope all of that is clear, and thanks to all in advance for your enlightenment.

 

 

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On 10/7/2024 at 6:31 PM, KLE-France said:

TLDR: What is the innate WORKING color space used by Affinity Photo? I am mostly curious about the Develop and Photo personas

Whatever you choose as document color space and color profile. For new files, you can set this in templates, for RAW images in Development Assistant.

Existing files can be converted at any time, but this can be lossy.

If you choose the bare minimum RGB/8 and sRGB, that’s it. Inspect the histogram and see how e.g. a curves adjustment creates spikes in histogram (when viewed enlarged). If you use RGB/16 it gets smoother.

There is no hard-coded „internal“ format, it is always the document format. Every operation like brush strokes or layer blending gets immediately / inherently stored and processed in document format.

 

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Thanks NotMyFault, I appreciate this quick response.

As they say, "trust but verify."

Where is this documented?

At Edit > Settings... > Color > RGB Color Profile, I have sRGB IEC61966-2.1 set.

So, if I'm understanding you correctly, when I open a raw image, it should be constrained to the sRGB color space. Now, a raw will also have 16-bit (more precisely 14-bit) color depth, so that is going to broaden greatly what can be done with color.

But, if I'm in the sRGB color space, that would mean that the colors in the raw, but outside of the sRGB color space would not be available to "rotate in" to what I see on the screen, right?

But that doesn't seem to be the case. Again, 16-bit depth, yes, but I can push, pull, squeeze and wring the daylights out of my underexposed and/or gradient-rich and/or high-contrast and/or high-saturation images, and never really run into problems related to a constrained color space.

Moreover, when I test this by changing the Settings color profile to ROMM sRGB, nothing seems to change in my ability to push, pull, squeeze and wring; It neither increases nor decreases.

BUT, I am conscious of the fact that I'm looking at all of this on a monitor that can only show in its entirety the sRGB color space.

But still, I do wonder if the Serif Labs raw engine doesn't innately use ROMM sRGB as the "holder" color space, as do RawTherapee and Lightroom (if the above link is correct)...

It would be great if a developer could sound in on this.

 

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It seems you are mixing up several aspects

  • RAW files are unbound, not bound to any color space. Only after clicking „develop“ the resulting document is converted into the specific color space and profile.
  • The colors you can see while Photo is open are limited by your Display color profile and capabilities (SDR or HDR, 8/10/12/14 bit channels)
  • color bit depth is unrelated/ independent from color space and color profile, but Affinity supports only specific combinations like RGB/8 and RGB/16 gamma encoded SDR and RGB/32 linear gamma HDR, using any color profile in appropriate gamma curve 
  • once you clicked „develop“ the color space and format is chosen and used for all further edit steps unless you convert again
  • While in Develop Persona, showing RAW data, Photo might be limited to a specific color format and profile. This is mostly irrelevant as you Display profile is far more restricted.

If you question is specific to what color profile is used while in Develop Persona: i don’t know, and it is academic/ irrelevant as you Display Color Profile (sRGB / AdobeRGB/Display P3) is more limited and you are unable to detect any difference.
 

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My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

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6 hours ago, KLE-France said:

So, if I'm understanding you correctly, when I open a raw image, it should be constrained to the sRGB color space. Now, a raw will also have 16-bit (more precisely 14-bit) color depth, so that is going to broaden greatly what can be done with color.

No. More color channel bit depth does not extend the color gamut (visible colors). It just avoids banding artifacts and loosing color details within the color space, caused by a limit range of color values. If you use 2 bit color depth, you only get black and full red/green/blue without any intermediate colors. 8 bit gives you 256 steps, 10 bit 1024, leading to smoother gradients and avoiding banding.

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iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

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6 hours ago, KLE-France said:

But, if I'm in the sRGB color space, that would mean that the colors in the raw, but outside of the sRGB color space would not be available to "rotate in" to what I see on the screen, right?

there is no sRGB color space, we have only RGB color space, or LAB, CMYK, GREY.
sRGB is a Color profile which is actually limiting color gamut. But you can use RGB color space with ROMRGB or Display P3 profile to achieve a wider gamut.

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Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

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This Spotlight article might be of interest:

https://affinityspotlight.com/article/raw-actually/

In the paragraphs headed "Colour" it tells us

Quote

Affinity Photo is no different in this regard: in its Develop Persona, colour-based adjustments are performed within ROMM RGB (otherwise known as ProPhoto, a large gamut profile), which allows for colour values far outside the range of sRGB. When the RAW image is finally developed and passed to the main Photo Persona, it is converted to sRGB by default. This output profile is of course configurable, should you wish to continue working in a different (often wider) colour space.

 

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On 10/7/2024 at 6:31 PM, KLE-France said:

What does "Output profile" mean on the Profiles tab in the Develop Persona? Is it just preparing AP to assign X (sRGB, Adobe RGB...) profile to the image at export, OR, is it converting the working color space to X profile when it develops the image toward the Photo Persona? Is so, that would mean that once in the Photo Persona, you are now working in a constrained color space. In this scenario, would it be correct to set the ROMM space there, before developing to the Photo Persona? 

The 2nd option after OR is what happens:

  • When opening a RAW file, the RAW data gets interpreted and converted into ROMM (thanks to @pbasdf for the missing piece)
  • when clicking „develop“, the image will be converted into the selected target color space (RGB, LAB, CMYK, GREY), and to the color profile. 
  • You can use the Develop Assistent settings to specify which color space and profile will be used for the „Develop“ step
  • It totally depends on later edit steps which color profile makes sense to use. When you want to use RGB/8, don’t use ROMM as this would lead to severe banding e.g. in sky part of images.

 

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Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

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4 hours ago, NotMyFault said:
  • when clicking „develop“, the image will be converted into the selected target color space (RGB, LAB, CMYK, GREY), and to the color profile. 
  • You can use the Develop Assistent settings to specify which color space and profile will be used for the „Develop“ step

I think it's always RGB. But you get a choice of 16- or 32-bit, and of the color profile.

-- Walt
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To  NotMyFault and pbasdfthank you so much for these explanations and resources!

Color management (EDIT: and color science!) is just such a monster; once I start thinking I'm understanding a bit of it, I fall on yet another gear in the motor, and re-realize that there is still so much I need to grasp before I can truly understand that motor in its entirety. But thanks to your insights, I'm a bit closer to that than I was a few days ago.

Again, thanks, and a thanks also to Affinity (and the other program developers) for making the use of the program as idiot proof as possible.

Cheers! And happy shooting to all.

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Because this discussion has sent me down the rabbit hole again, I'll add the following links, because one of the huge challenges I have with all of this is a terminology and a pseudo-synonymy that, at least for me, is extremely confusing.

So, in the hopes of helping some future person who could fall upon this conversation and be as confused as I am, here are links to the Wikipedia articles (for what that's worth) for:

And here is a link to a gnome.org article for

This last one does not have a specific Wikipedia article and I think that it in particular suffers from a "synonym use syndrome," popping up here and there when a person is actually speaking of a color model or a color space... Bref, as is obvious from my posts above, I could be wrong about that.

Re-Cheers!

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2 hours ago, KLE-France said:

Color management (EDIT: and color science!) is just such a monster; once I start thinking I'm understanding a bit of it, I fall on yet another gear in the motor, and re-realize that there is still so much I need to grasp before I can truly understand that motor in its entirety. ...

Here is an xkcd comic to let you know you are not alone.

https://xkcd.com/1882/

 

Mac Pro (Late 2013) Mac OS 12.7.6 
Affinity Designer 2.5.5 | Affinity Photo 2.5.5 | Affinity Publisher 2.5.5 | Beta versions as they appear.

I have never mastered color management, period, so I cannot help with that.

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As someone with a math background, color spaces and color manipulations themselves aren't the challenge.  The challenge is that most app developers want to hide all the specifics and occasionally do silent automatic conversions behind the scenes to "make it easier for the user".  Adobe has been as guilty of that as anyone else (e.g., automatic color space conversion when opening files).  If this stuff is hard to learn, it becomes 10x harder to learn when the app refuses to tell you what it's doing.

At one point CorelDRAW had the best presentation of what was going on for color management of any app I've worked with.  It showed you the profiles in use for input document, output document, screen, and printer and also showed the flow (transformations) between those.  Nothing about the process had to be guessed or inferred from fragmentary information.

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7 hours ago, walt.farrell said:

I think it's always RGB. But you get a choice of 16- or 32-bit, and of the color profile.

Probably you are right. What is possible and maybe unknown:

having an CMYK document with RAW layers, either by converting from RGB or starting as new file and then placing RAW files. You can choose any RAW/pixel layer, enter develop persona and find histogram is in CMYK.

IMG_1807.png

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iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

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On 10/9/2024 at 1:55 PM, NotMyFault said:

Probably you are right.

It is definitely true that the Develop Assistant Options only allow RGB and 16 or 32 bit :)

I hadn't thought of Placing a RAW image into a CMYK document. Thanks for the idea.

  1. You're right that when you do that, and go into the Develop Persona, the Histogram shows CMYK channels.
  2. Additionally, if you Cancel the Develop process, so you're back in the CMYK main document with a Linked (didn't try Embedded) RAW image layer, you can Copy that layer and do a File > New from Clipboard.

    Doing that, I got a new document that is in CMYKA/8:

    image.png
    And according to the Resource Manager the document contains a Linked RAW layer in RGB:
    image.png.663c3a19901068c3b5ef784bc4661912.png

-- Walt
Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases
PC:
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