Using Affinity Photo to create and view images for HDR displays

[Julian Vrieslander]

This post is an expansion of notes that I wrote for myself, a summary of instructions for creating photos optimized for viewing on an HDR-capable display. In what follows, "HDR" does not refer to the well-known method for merging multiple shots, made at different exposures, and tone-mapping the result into a narrower dynamic range for print or sRGB web output. Here, HDR refers to any image, software, or device that is capable of high dynamic range display. "XDR" is Apple's marketing term for their HDR displays with miniLED or OLED backlighting, and "EDR" is Apple's term for the macOS imaging pipeline for HDR images.

There are well established industry standards for video content rendering in HDR: DolbyVision, HLG, HDR10, and HDR10+. But the standards and file formats for static photos on HDR displays have been slow in coming. VESA is promoting certification levels for HDR-capable monitors, using the "DisplayHDR" label:

https://displayhdr.org

Adobe just announced a version of Adobe Camera Raw that can edit in an HDR mode for export in the JPEG XL (aka JXL) format. They are currently calling it a "Technology Preview." It is only available on macOS. I have not tried it.

https://helpx.adobe.com/ca/camera-raw/using/hdr-output.html

https://www.dpreview.com/forums/post/66552610

For more information on the technology and the emerging standards for HDR image display, read Greg Benz' excellent introduction. His webpage includes examples and test images that reveal whether your monitor and browswer are capable of HDR display:

https://gregbenzphotography.com/hdr/

Currently I am using Affiinity Photo to edit my images for HDR viewing. Unfortunately, the current version of this app (1.10.5) does not export to JXL or any other color managed HDR file format. So this method is certainly not optimal, and not very practical. Consider it an experiment, and a demonstration of what may be possible in the near future.

Some samples of my HDR photos are in this directory (ignore any files with names that begin with a period):

http://julian.marmotandweasel.com/photos/HDR/

You can download the files and view the images in any application that reads files in the EXR format, including Apple's Preview and Photos. But they will only look correct in the environment that created them: Affinity Photo, running on Apple's XDR displays (e.g., Pro Display XDR, 2021 14" and 16" MacBook Pros). The EXR format does not include an embedded profile. So most apps will probably default to sRGB, which will desaturate the images. With apps and monitors that are not HDR-capable, you will likely see washed out or incorrect colors, and highlight clipping.

My starting point is usually a single raw (NEF) file from a Nikon D800E or D850. These files can contain up to 14 stops of dynamic range in a single exposure. The files are transferred to a 2021 M1 Macbook Pro and loaded into Affinity Photo, configured as follows:

macOS 12.6 Monterey

System Preferences > Display > Presets = Apple XDR Display (P3-1600 nits)

System Preferences > Displays > Brightness = set to 50%

Affinity Photo 1.10.5

Preferences > RGB Color Profile = Display P3

Preferences > 32 bit RGB Color Profile = Display P3 (linear)

Preferences > Rendering Intent = Relative Colorimetric, with BPC

Preferences > Enable EDR by default in 32 bit RGB views = YES

Develop Assistant > RAW Engine = Serif Labs

Develop Assistant > RAW output format = RGB (32 bit HDR)

Develop Assistant > Tone curve = Take no action

Develop Assistant > Exposure bias = Take no action

32-bit Preview > Enable EDR = YES

All other settings are at defaults. After editing a raw file in Affinity Photo's Develop persona, I switch to the Photo persona, and export a file in OpenEXR 16- or 32-bit linear format (.exr).

The Affinity website has a couple of video tutorials that describe HDR editing in more detail. I'm hoping that they will soon release an update that can export to the color-managed JXL file format.

https://affinity.serif.com/en-gb/tutorials/photo/desktop/video/340676972/

https://affinity.serif.com/en-gb/tutorials/photo/desktop/video/341759551/

Here is a video introduction to Apple's EDR technology, for software developers. It might be interesting for non-developers who want to learn more about how HDR works.

https://developer.apple.com/videos/play/wwdc2021/10161/

 

[Dave_J_E]

Thanks for sharing your info and images. Now that I have figured out how to use the 32bit preview in Affinity properly, your images look pretty good on my pc connected to my HDR TV. The color is not bad, blues might be a bit out. I've made a few of my own .exr image files on my pc and the process works quite well.

I guess the key to this topic is the acceptance of a standardised HDR image file format by the industry (jpeg xl?) and the availability of suitable display software that allows easy sharing and compatabiity across all operating systems. In the meantime, it would be nice to be able to process for HDR on an iphone or ipad with HDR display. Maybe the jpeg xl can do this, I don't know. (and I can't test it as I don't have Adobe PS cc or a mac!)

Dave

 

[robgendreau]

Thanks for that.

I have messed with Ps's new implementation. It's quite a surprise when you click on the HDR button and suddenly get 4 stops or so of extra headroom, and see what looked blown out, like bright sky, suddenly become clearly defined. With no change in shadows.

The downside is I think Ps only exports JPEG XL/JXL export. I'm not sure I've got the export working properly in Ps; I get only very dark images. I think I didn't have the right bit depth on it, as well as some other errors.

But Graphic Converter opened the JXL.

There's a JXL viewer, JXLook. At GitHub. Very nice; even supports QuickLook for JXL. And tev, which can view the exr's posted here.

And more info re JXL here: https://jpegxl.info/