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Develop persona appears to be limited to the gamut of sRGB!

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Hi >|< :)

One of our devs, Andy Somerfield has commented on this previously, I recommend reading through the following thread:

We're aware of a bug currently that the tonal clipping overlay values are bounded to the sRBG gamut, but this does not affect the overall colour space in Develop.

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On 10/19/2018 at 4:30 PM, >|< said:

3. Immediately after clicking the Develop button, the context toolbar briefly states that the output image's profile is sRGB and then that changes to the name of the specified output profile as if a conversion from sRGB to the specified profile is occurring.

@Dan C I don't have a camera that shoots RAW but I have been testing with files in various RAW formats that I downloaded from the web. With the Develop Assistant set to use the RGB (32 bit HDR) RAW output format, while the Develop progress bar is displayed I also see the sRGB profile displayed when I click the Develop button. Immediately after the bar disappears, it changes to whatever color profile I have set in Preferences > Color > 32 bit RGB Color Profile.

So, considering what @Andy Somerfield said about using something "very similar to ProPhoto," would I be correct in assuming that if I set that preference to ROMM RGB: ISO 22028-2.2013 (Linear), development is not actually using the narrower sRGB profile as some sort of intermediate profile & I would end up with the wider ROMM/ProPhoto profile without clipping out-of-gamut colors, or color shifts or whatever because the profile is similar to but not identical to ROMM/ProPhoto?


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2 minutes ago, R C-R said:

would I be correct in assuming that if I set that preference to ROMM RGB: ISO 22028-2.2013 (Linear), development is not actually using the narrower sRGB profile as some sort of intermediate profile I would end up with the wider ROMM/ProPhoto profile without clipping out-of-gamut colors

That's correct!

Clearly Affinity is drawing the incorrect profile in the context toolbar when developing, but the image itself is definitely not being clipped to sRGB values :)

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18 hours ago, >|< said:

Dan, are you personally checking this with AP 1.6.7 on a wide gamut Mac?

Not personally, but my colleague Leigh is doing so as he has a wide gamut Mac and we're using the digital colour monitor app built into the Mac to verify results.

Could you provide a copy of this image for us to test here and screenshots showing the values you're seeing?

18 hours ago, >|< said:

displayed colours while working in the Develop persona are constrained to the sRGB gamut despite my P3 screen displaying colours outside of sRGB when I work on ROMM-profiled documents in Photo persona

What are you using to measure this please?

Taken from our Spotlight Article (under the Colour heading) written by @James Ritson;

During RAW development, the software assigns the image a colour space, and translates the colour values from the camera’s colour matrix to that colour space. Most software will typically ‘develop’ in a wide colour space (such as ProPhoto), which provides more flexibility for manipulating colour values, before converting to a standardised colour space like sRGB upon saving. 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.

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Thank you for that. I've spoken with James and I believe we've discovered the issue.

When opening a RAW into the Develop Persona, the displayed image is narrowed down to the sRGB gamut, however the actual value behind this display is correct due to the floating point arithmetic in use.

This allows for colours to extend beyond the sRGB gamut and not be clipped when developing, hence you see the correct values in the Photo Persona.

We'll continue to investigate this and I'll pass all the information collected through to our developers.

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To clarify, the general Develop process is done in sRGB float—this includes the initial conversion from the camera's colour matrix to a designated colour space. However, the colour data is processed in ROMM RGB which produces enormous benefits for some type of imagery, particularly low light images with lots of artificial lighting sources. Despite this, the document is in sRGB and so this is the colour profile used when converting to the display profile.

As the pipeline is in float, this does mean that you can convert to a wider colour profile on output and avoid clipping to sRGB, which is the recommended course of action for now.

3 minutes ago, >|< said:

It's not just the display that's limited to sRGB. The output image, even with the very wide gamut ROMM profile, is limited to sRGB gamut also!

Do you mean the final developed image? This isn't my experience—choosing an output profile of ROMM RGB and then using adjustments and tools within the Photo Persona allows me to push colours right up to the limit of P3.


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Thanks for all that analysis.

In my case, I do RAW -TIFF conversion in Capture One, I'm using Affinity mostly for HDR blending as it have great artefacts removing module.

I merge TIFF 16 bit Pro-Photo  to EXR Pro-Photo.

I've also stack photos (same imput) in u-mean mode- to bump Signal to noise ration from small sensors -> like drone sensors. In that case I stack photos then I change document color space to 32 bit then rasterise.

What you wrote here is that I will loose some colors because of internal sRGB color space?

 

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What @>|< means is that the Affinity Develop Persona, aka the RAW conversion portion of the software, is or might be restricted to the sRGB color space in terms of overall used color values there (a much more restricted color gamut). - Camera RAW files are usually kept in a Sensor Native Color Space and then during Post processing software converted into some working color space, here working color spaces like Adobe RGB or ProPhoto RGB etc. do offer to deal with/handle much more colors than sRGB.

See for example ...

... and similar other articles about that theme.

 


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10 minutes ago, v_kyr said:

@>|< Affinity Develop Persona, aka the RAW conversion portion of the software, is or might be restricted to the sRGB color space in terms of overall used color values there (a much more restricted color gamut).

Thanks for clarification!

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