AFPhoto PNG export looks bad

[mopperle]

I opened a DNG file (scanned slide with Nikon LS400) in Photo, made corrections, then develop and exported as png. Everywhere including in the export preview all looks good, but the final png looks poor in any other viewer I use (Faststone, XnView, Irfanview). Exporting the same image as jpg, everything looks fine:

Screenshot 1 after working in Photo persona, clicking on develop with the png export window:

Screenshot 2 how the png looks in a viewer:

What did I miss?

[Ldina]

28 minutes ago, mopperle said:

What did I miss?

Can you send screenshot of ALL your PNG Export settings? (including the ones that are hidden in your original screenshot). Which PNG preset did you start with? I suspect it is due to some export settings because my PNG images look fine in XnViewMP and other viewers.

[mopperle]

here you go:

16 minutes ago, Ldina said:

Which PNG preset did you start with?

The 1st one in the preset list, called just "PNG. Which one are you using?

[Ldina]

7 minutes ago, mopperle said:

The 1st one in the preset list, called just "PNG. Which one are you using?

Yes, I'm also using the first PNG preset. My PNGs look identical in XnViewMP. One thing I noticed that is different in your screenshot. For some reason, your ICC Profile Box is empty. My ICC Profile is set to "Use Document Profile". The rest looks the same. 

I suspect your ICC profile is missing, perhaps another ICC profile is being embedded, or something is messed up and your profile is not being exported with the image. Try looking at the metadata in the exported PNG file and see if it has a profile and that it is the same as your document profile. Also, perhaps close and reopen AP. 

FWIW, I'm on a Mac and I noticed you are on Windows 11. I'm not a Windows user, but I have heard that the latest Windows version changed something regarding color management and it may have a few bugs/problems, totally unrelated to Affinity. 

[mopperle]

13 minutes ago, Ldina said:

I suspect your ICC profile is missing, perhaps another ICC profile is being embedded, or something is messed up and your profile is not being exported with the image. Try looking at the metadata in the exported PNG file and see if it has a profile and that it is the same as your document profile. Also, perhaps close and reopen AP. 

This is what the dng tells me:

But even when i choose the "sRGB IEC..." profile or "user document"or other combinations, I always get the same poor result. So I wonder what sense makes the preview in the export Window when you finally get something totally different.

Usually I do RAW developing with LrC, but in this case I get better overall results with Photo. I just tried it with LrC and the exported PNG looks exactly like what I see in LrC.

23 minutes ago, Ldina said:

but I have heard that the latest Windows version changed something regarding color management and it may have a few bugs/problems, totally unrelated to Affinity. 

Never heard of that, so do you have a source?

[mopperle]

Forgot to add that both PNG and JPG have the same ICC profile as the DNG: "sRGB IEC61966-2.1 (linear)"

[Ldina]

9 minutes ago, mopperle said:

Forgot to add that both PNG and JPG have the same ICC profile as the DNG: "sRGB IEC61966-2.1 (linear)"

Is the develop persona set to 32 bit, and are you working in HDR? If you don’t need 32 bit HDR, set develop persona so it exports16 bit files to AP. You’re probably exporting from AP to PNG using document profile, which is 32 bit linear gamma, which is why the images look bad in other viewers. I always use 16 bit export from Develop Persona to AP unless I purposely NEED to be working in HDR (which is rare).

I  don’t have any source for the Windows color management issues, since I’m on Mac. Just a few things I’ve read. I suspect your problem is due to using 32 bit instead of 16 bit.

[Ldina]

You should also be able to export a 32 bit file to PNG, but instead of “use document profile”, choose 8 or 16 bit. That ought to convert from 32 bit linear to 8/16 bit 2.2 gamma during export. I’m not at my computer but I think that will work.

[mopperle]

thx, will try tomorrow

[Ldina]

@mopperle I ran a few tests with 32 bit files and PNG export. I believe your problem is that you are exporting 32 bit linear PNG files.

First, if your final image will be HDR, then you'd want to develop your RAW files in the Develop Persona using RAW Output Format: RGB (32 bit HDR). When you click "Develop" the file will be sent to AfPhoto as a 32 bit file with a Linear Tone Curve, with whatever colorspace you chose (ROMM RGB is the default, but you can change it if desired). If you don't convert the file to 16 or 8 bit, you will remain in 32 bit linear mode while editing. This preserves all the HDR tones in the image. Normally, you'd choose a PNG Export Preset that is designed for HDR images and saves as 32 bit linear. If you want a standard image, you do NOT want to export to 32 bit (many Browsers, Apps and Image Viewers don't display 32 bit files properly). 

You had a 32 bit Linear file in AfPhoto and chose the top PNG Setting, which is normally used with 8 or 16 bit files. You can still export a 32 bit file correctly to SDR (standard dynamic range), but you have to select RGB/8 or RGB/16 for the Pixel Format, as shown in the screenshot below. You left it at the PNG default (Use Document Format), so your PNG was exported as RGB/32, which many Viewers won't display as expected. Use Document Format is fine when you export RGB/8 or RGB/16 because they use a 2.2 Gamma Tone Curve (rather than Linear). So, when you work in 32 bit and want your final image to be SDR, change the export pixel format to 8 or 16 bit. You can then choose whatever color profile you wish and the file will be converted from 32 bit Linear to your chosen format and profile at export time. 

It's preferable to change your Develop Persona Assistant settings to 16 bit for normal work and not to use 32 bit at all (unless you REALLY NEED your final images to retain all HDR tones, which is unlikely unless you are doing some special HDR work, 3D, etc). 

If you bring a 16 bit image into AfPhoto, you can use the Standard PNG Export Preset (the first in the list) as is. Leaving the Pixel Format to "Use Document Format" will be fine, since it will just leave it set to 16 bit and export and display properly. (I tested it and that's the case). If you choose 8 bit as the pixel format, your files will be smaller and still look very good, since PNG is a lossless format. 16 bit is usually better if you plan to do further work on the file or send it to someone who will use it in a high end workflow. 

I think this will solve the problem. Your development in LRC was probably using standard 16 bit with a 2.2 gamma Tone Curve, which is why it exported and looked correct in XnView. 

[mopperle]

6 hours ago, Ldina said:

but you have to select RGB/8 or RGB/16 for the Pixel Format

Thanks @Ldina, that exactly solved the problem. Learned again something.

Interesting for me how different this is being handled in Photo compared to LrC, where it is much easier. To keep it as 32bit HDR I tried the HDR presets and got the best result with "PNG-HDR (HLG, Rec.2020, Full Range)", but still not as good as the standard jpeg export, which I will use.

Again, thanks for your help.

[Ldina]

6 hours ago, mopperle said:

LrC, where it is much easier.

The last version of LR I used was the standalone version 6, so it's been long time. That version didn't handle 32 bit or HDR at all, so there was really only one workflow, which did make it simple.

The PNG export settings in AfPhoto could be clearer and more user friendly, especially for those who are not very familiar with HDR and 32 bit. Added flexibility comes with added complexity. 32-bit files exported as 32 bit, with PQ or HLG transfer functions, will look fine when re-opened in AP, with 32 bit enabled and when using an HDR capable monitor. But those same files don't look the same in many file viewers and browsers due to lack of support. HDR is still 'evolving' and is not well supported, including many of the file formats. I suspect AVIF with gain maps will be widely accepted at some point, along with standard JPEG format with the addition of gain maps. Hopefully, JPEG-XL will be too, and perhaps a few more. Those formats (when supported) should enable the end user to automatically see correct HDR and/or SDR versions of an image, depending on their monitor capability (HDR or SDR) and the application used to view those files. We're not there yet. 

Best general advice...Avoid working in 32 bit unless you REALLY need it and require HDR final output. Then all will be well and will stay within standard dynamic range.

Glad the above solved the problem for you.