Trying to figure out EDR on Mac Affinity Photo

[Reflex]

I'm having difficulties understanding EDR / not able to make it work in Affinity Photo 1.10.5.

I have a Mac Studio running Monterey (12.4) connected to an 8K LG TV for a monitor (LG 65NANO95) through a DENON HDR compatible receiver. The option for HDR is available in Display Preferences, and activating it causes the TV to show a HDR badge. The DENON shows it's passing through a 12bit HDR10 YCbCr 4:2:2 signal with profile BT2020.

I take a ProRAW photo with my iPhone 12 Pro, and open it in Affinity. Depending on the various assistant settings it can look quite washed out, or alternatively underexposed.

I've found that if the assistant is set to

• Apple core image RAW
• Apply tone curve on (off and it's too dark)
• Display transform is unmanaged (ICC makes it washed out)

Then I will get a nice looking photo which resembles what I expect / version displayed in Photos. Problem is ticking the EDR option has no effect on the image. It indicates a max 3.35 / +1.74EV and ticking EDR clipping shows affected areas when I push up the exposure, but the image itself doesn't change when EDR is on (other than the clipping indicator when that's on).

On the other hand, if I set the following:

• Serif Labs engine
• all assistant options to no action
• Display transform to ICC

Then the image initially appears very dark, and I have to thrust exposure up to +5 to bring it up to realistic levels, but the image loses saturation. However flicking the EDR setting on and off does at least show a difference in the highlights.

This behaviour isn't what I would expect. I'd be hoping that there would be some combination of settings which open the initial image in a reasonable state, and turning on the EDR option would allow the highlights to shine even brighter.

What is it I'm doing wrong?

[v_kyr]

That's probably theme wise something @James Ritson can answer best. - Thus I'll point you here just to one two common references related to this topic  ...

• HDR/EDR workflows (tutorial video)
• HDR from one exposer (tutorial video)
• 32-bit HDR editing (online help)
• List of EDR/HDR compatible displays (forum thread)
• HDR/EDR output from OCIO config being clamped before display (forum thread)
• ... etc. - a Google search might give you additional refs ...

[James Ritson]

Hi @Reflex, hope I can help. This right here:

6 hours ago, Reflex said:

• Apple core image RAW
• Apply tone curve on (off and it's too dark)
• Display transform is unmanaged (ICC makes it washed out)

Is where you might be going wrong—applying the tone curve is a bounded operation and it will clamp values to between 0 and 1, so you won't be seeing any extended brightness values. This is why it defaults to "Take no action" when you change from RGB/16 to RGB/32—it's not intended to be applied if you wish to retain HDR values.

Secondly:

6 hours ago, Reflex said:

• Apple core image RAW
• Apply tone curve on (off and it's too dark)
• Display transform is unmanaged (ICC makes it washed out)

Will also be wrong: you want ICC Display Transform otherwise your document will not be colour managed. Unmanaged means you are seeing the linear scene referred values, which you don't want in this case as things will look dark and "crushed".

Have you tried using the Apple Core Image RAW engine but with no tone curve and ICC display management applied? You mention that the tone curve being off results in the image looking too dark, but then at the same time you're using an unmanaged linear view—which will indeed look dark because it doesn't have a gamma transform correction.

Try:

• Apple Core Image RAW engine / SerifLabs engine
• Tone curve set to Take no action
• 32-bit Preview set to ICC Display Transform

And see how you go from there—it's possible that we don't apply some exposure corrections or other parameters stored in the ProRAW format, so you may have to experiment. Possibly the Apple Core Image engine will handle this better than the SerifLabs engine.

It's no bad thing that you should have to push the exposure slider up: it's kind of the intention that users should shoot to capture highlight detail (underexposed if needs be), then be able to simply push the pixel values linearly and still see those bright highlights rather than having to tone map them using highlight recovery and other techniques.

[Reflex]

5 hours ago, James Ritson said:

Hi @Reflex, hope I can help. This right here:

Is where you might be going wrong—applying the tone curve is a bounded operation and it will clamp values to between 0 and 1, so you won't be seeing any extended brightness values. This is why it defaults to "Take no action" when you change from RGB/16 to RGB/32—it's not intended to be applied if you wish to retain HDR values.

Hi @James Ritson. Thanks for the reply. This part actually makes some sense to me. Sometimes I think I understand HDR & EDR theory, and then suddenly that illusion falls apart. Although I would have expected that even if the values did get clamped, pushing up the exposure while in develop mode would extend them again.

5 hours ago, James Ritson said:

Secondly:

Will also be wrong: you want ICC Display Transform otherwise your document will not be colour managed. Unmanaged means you are seeing the linear scene referred values, which you don't want in this case as things will look dark and "crushed".

This also makes some sense. If the image uses linear values but the system interprets them as exponential (i.e. gamma adjusted) then it compresses the darker values and expands the lighter ones. Yet this gave me the most realistic result. The ICC option crushed everything at the highlight end. I'm guessing the curve mapping applied gamma adjustments but the system assumed linear still. Unexpectedly it even washed out the black of the interface surrounding the image.

On a related observation, while Preview indicates a profile of Apple Embedded Colour, Affinity indicates the colour space under EXIF is uncalibrated.

5 hours ago, James Ritson said:

Have you tried using the Apple Core Image RAW engine but with no tone curve and ICC display management applied? You mention that the tone curve being off results in the image looking too dark, but then at the same time you're using an unmanaged linear view—which will indeed look dark because it doesn't have a gamma transform correction.

Try:

• Apple Core Image RAW engine / SerifLabs engine
• Tone curve set to Take no action
• 32-bit Preview set to ICC Display Transform

And see how you go from there—it's possible that we don't apply some exposure corrections or other parameters stored in the ProRAW format, so you may have to experiment. Possibly the Apple Core Image engine will handle this better than the SerifLabs engine.

It's no bad thing that you should have to push the exposure slider up: it's kind of the intention that users should shoot to capture highlight detail (underexposed if needs be), then be able to simply push the pixel values linearly and still see those bright highlights rather than having to tone map them using highlight recovery and other techniques.

This is essentially the combination I mention as being too dark, then becoming less saturated when levels are increased. Note that I'm talking about having to go to the maximum exposure just to be realistic brightness for a normally exposed image, and then it becomes very flat.

As a picture is worth a thousand keystrokes, I've attached images of various combinations of settings. Most of them are screen shots of the images open in Affinity, but I've also included the original DNG as well as a screen shot of it open in Apple's Photos and exported as a PNG for comparison. On my screen at least, the Photos presentation, Preview and quicklook are all close to being identical. But I can't get the Affinity Photo treatment to come close without requiring a lot of "corrections".

Hopefully the filenames will indicate what they relate to. It feels like the ProRAW file has an embedded profile reflecting the behaviour of Apple's devices, and this profile is being used by Quicklook, Preview and Photos, but ignored by Affinity.

Original.DNG

[Reflex]

8 hours ago, v_kyr said:

That's probably theme wise something @James Ritson can answer best. - Thus I'll point you here just to one two common references related to this topic  ...

• HDR/EDR workflows (tutorial video)
• HDR from one exposer (tutorial video)
• 32-bit HDR editing (online help)
• List of EDR/HDR compatible displays (forum thread)
• HDR/EDR output from OCIO config being clamped before display (forum thread)
• ... etc. - a Google search might give you additional refs ...

Hi @v_kyr. Appreciate you taking the time to reply. I had already read / watched all of those apart from the OCIO one. It was watching the first ones which left me wondering why my photo wasn't behaving the same way. Perhaps it's a ProRAW thing?

I've also noticed that there is a box to clip to the limits, but if I turn off EDR then turn it back on again, the clipping option becomes ghosted but fixed as active.