How to correct measure a value - photoshop read file wrong - Solved !

[PatrickMarq]

I’m having a lot of problems with creating digital negatives with a darkroom service.

As an analog photographer I scan my negatives as 16bit B&W TIFF files, do a little bit of tweaking and use the ‘pipes’ tool to read some values, just to make sure my whites are not blown out. Full calibrated setup.
In about two months I have an exhibition and for this I have rented for two weeks a darkroom that offers a complete standard solution for making Platinum prints.

But when opening my exported TIFF files there in photoshop there is a message of unsupported channel ?

Also It seems that everything between 15% and 35% is to bright (even gone) I don’t see this at home.

Normally I make my prints at home, but now the size is too large for my home setup.

Anyone here an idea what could be wrong ? every print cost me about 200$ and i’m already with 4 prints that are not acceptable for me. And I have foreseen about 25 prints in total. I’m quite close to cancel everything.

Thanks

Patrick

[R C-R]

What is the 'pipes' tool? What application is that in?

Also, you mention Photoshop. What if anything does this have to do with Affinity Photo?

[PatrickMarq]

Pipet tool (looks like autocorrect error)

Affinity Photo (as tagged) Desktop in MacOS

As explained above, when opening a 16bit B&W TIFF file created / edited in Affinity Photo it seems there is some information lost/misunderstood in Photoshop.
The darkroom uses photoshop to make a digital negative.

[NotMyFault]

We would need an example tiff file to check, actually two of them: one scanned original, one edited.

based on the value ranges I assume you stored the images as grey/16 with a greyscale color profile. This color profile deviates in lightness in that value ranges from RGB/16 with sRGB profile (using the same numeric color values).

The most probable cause is a color profile issue.
you only mentioned you have checked color values.

1. Did you do any other edits in Affinity?
2. which exact file format and color profiles are used by scan?
3. which exact export options do you use?
   1. format and color profiles conversions?
   2. embed color profile in exported file?
      
       

[PatrickMarq]

I must come back on this, as i’m currently in the darkroom for the next two days.

I have seen already one problem that is completely my fault. As all the images needed to be the same size, I had created an empty document and used place. To insert and resize the image.
Apparently the ‘master’ file was RGB/16, and the people of the darkroom have converted them to Grey 16bit without saying something.
Tomorrow I’m back there with files that are 16bit generic b&w 2.2 gamma.

I’ll keep you posted.

[PatrickMarq]

After a lot of checking it seems that I have something ‘stupid’.

Yesterday I needed to create some new files for the darkroom, and created a new file with ‘color’ profile b&w 16 bit gamma 2.2
Placed there my scanned image in, and exported as tiff also with b&w 16bit and gamma 2.2.

Hereafter there was no problem opening the file in photoshop and there was no error.

Thank you all for having patience with me.