Rendering Intents are not giving different results

[toodee]

Hi, I am writing a blog post about exploring a simple made up image in different colorspaces. https://www.toodee.de/?page_id=5496

 

I set up a document in sRGB.

Next, I assign this document the Rec.2020 primaries that I obviously cannot display on my iMac.

Then I convert the document back to sRGB trying different rendering intents. 

01 - looks right

02 - looks broken because I cannot display it

03a and 03b look okay again, but shouldn't the two conversions end up differently?

 

Thanks for your help.

 

Daniel

 

 

01_start_sRGB.afphoto 02_assign_Rec2020.afphoto 03a_convert_to_sRGB_relative.afphoto 03b_convert_to_sRGB_absolute.afphoto

[NotMyFault]

Your image 02 looks ok on my iMac / LG P3 display.

If you "cannot display It" (what does this mean exactly?), I would check the overall hw/sw chain.

The differences caused by rendering intends might be too subtle to be visible on your display. 

My method to make small differences visible:

1. - merge visible for "absolute"
2. copy layer atop "relative" file, set blend mode to difference
3. add levels with white level set to 10% ... 1% 

Now you can spot all differences.

 

 

[NotMyFault]

You may try the image below, it contains all possible 16.7 million colors possible with 24 bit. just assign a different color profile. I'm sure the differences will be better noticeable, as about 30% of those colors will get changed.

all8bitcolors.afphoto

[toodee]

Thanks for your reply.

 

I think I misunderstood the rendering intents absolut and relative and how they work.
I was expecting a different result.

[toodee]

Hi, 

you said you can see image 02 fine on your display?

I cannot. I see a dark halo around the star and a light halo closer to the center of the star.

I cannot display an image with BT.2020 primaries, because I would need a laser projector/display to do so.

I was expecting a different result by the conversion to to sRGB operation.

I can confirm in Foundry/Nuke that a JPG export from image 01, 02 and 03a and 03b end up as the same image.

As far as I understand it, this should not be like this?

I can also convert the Rec.2020 document to sRGB and set the rendering intent to perceptual and saturation and still end up at the same result as image 01.

It could be that something is not working properly in my Affinity Photo?

 

 

[toodee]

I may have spotted where my problem is:

 

I use an OCIO config in Affinity Photo. Can it be that the profile conversion is not working right as long as an OCIO config is enabled?

After a reset of Affinity Photo and I did another conversion from image 02 to image 03b I get this result. I hope this is more likely to what I should see and expect.