Another Color Profile Problem

[chris_s]

I looked through a number of previous posts on this topic and that didn't lead to an obvious answer. This is the situation:

• Loading a raw file (RAF) or the JPEG thumbnail from it works fine and everything looks normal.
• Loading a .tiff file converted from the RAF file (using DCRaw) triggers the warning about using a default profile (sRGB) because it is an unprofiled document. It creates a very dark over-saturated image in Affinity. This .tiff can be opened in other applications (e.g. Windows Photo Viewer) and displays correctly.
• Everything is defined as sRGB (the camera, the file, the monitor and the Affinity RGB color profile).

I found that if I go into Color Balance and choose 'screen' rather than 'normal' it makes the image look proper. Is this normal behaviour and if so why.

 

 

[MEB]

Hi chris_s_

Welcome to Affinity Forums :)

Can you please attach the converted tiff from DCRaw here so we can take a look (or post a link to a shared file hosted on a file/cloud sharing service if it's too big - max file size in the forums is 20Mb).

[chris_s]

Here is a link to a tiff sample

 

link

[James Ritson]

Hey Chris, so if I understand correctly, Photo is decoding the RAF successfully? Is the only issue with the separate dcraw TIFF output?

 

I've tested with a sample X-E2 raw file and I'm able to produce an output that opens properly within Photo in sRGB. Have you tried explicitly defining the output colour space? Try the -o command line switch, so use "-o 1" for sRGB, or you could use "-o 4" for ProPhoto.

 

I can't account for why the gamma transform looks different in Photo compared to Windows Photo Viewer, but ideally you don't want to be working with unmanaged or untagged image files anyway (with the exception of JPEGs for web perhaps), because different programs will produce different results based on how they colour manage and transform the image.

 

The TIFF sample you've provided isn't tagged with any colour space. Are you able to provide the command line parameters you've used? If you ensure you set an output colour space with dcraw you shouldn't run into any issues though. Hope that helps!

[chris_s]

What does Aff Photo use to determine that an image is 'unprofiled.'

 

Just to be sure, I downloaded the file that I sent you the link for. I had a look at the EXIF info and it shows:

• Photometric Interpretation: RGB
• Color Space Data: RGB (in ICC Header)
• Profile Description: sRGB (in ICC_Profile)

FYI: DCRaw defaults to sRGB (-o 1) so it puts in the 3 fields shown above and thinks that this is adequate to define it as sRGB.  Maybe Photo is looking at some other field(s) as well.