Question: tags in tiff file from RT

Software RawTherapee
#1

Hello again RT forum,

I converted a Canon CR2 RAW to 16-bit TIFF using RT Queue with RTv4-Medium output profile with Rendering intent “relative colorimetric”. The files are here. (The image is part of a focus stack).
filebin link, as an alternative.
https://filebin.net/kzdjf7h7700qln1f

  1. I get “Rendering Intent : Perceptual” as a tag in the TIFF file. Should this be “Rendering Intent : Relative Colorimetric”, or similar? Does this matter for a printer receiving the TIFF file?
    Command: exiftool _Y8A8348-AdobeRGB.tif | grep Rendering
    Result: Rendering Intent : Perceptual

  2. Command: identify _Y8A8348-AdobeRGB.tif displays as:
    _Y8A8348-AdobeRGB.tif TIFF 4492x6732 4492x6732+0+0 16-bit sRGB 173.045MiB 0.000u 0:00.000.
    This the Imagemagick command identify. I wonder why identify outputs “sRGB”? (This is ultimately a question to Imagemagick developers).
    However, Command:
    identify -verbose _Y8A8348-AdobeRGB.tif | grep Colorspace
    shows:
    “Colorspace: sRGB”.
    Why is “Colorspace” set to “sRGB” in RT TIFF output when I pick RTv4_medium (AdobeRGB) as output profile?

There are hundreds of lines of data from identify -verbose and exiftool. Honestly, I do not know if the output above matters at all. Perhaps my 16-bit tiff file renders perfectly when printed at the printing company and tags quoted are irrelevant? I do not know.

Environment:
Debian Testing
RT 5.8-2838-g8bf1098d7 from source

#2

Ok, for question 1, the “Rendering Intent : Perceptual” seems to originate from the working and output profiles in RT.

exiftool RTv4_Medium and
exiftool RTv4_large
both have
“Rendering Intent : Perceptual”

This was also the feedback from the printing company, in my case. They try to use the embedded profile’s rendering intent.

#3

Did you use the fast export, the batch queue, or a one by one export?

#4

I used “put image to queue” from main edit window for the CR2 RAW file and then in queue tab I selected tiff (16-bit) and pressed “on”. I exported only one picture. I did not use “save current image” from main window.

#5

Could you shrink your image and plop it into a post? I can’t download from your link for some reason.

#6

Try this filebin link, as an alternative.
https://filebin.net/kzdjf7h7700qln1f

A new link to Google drive is here:
https://drive.google.com/drive/folders/1iyu065GujC6Fya94inXiN7_8elXGSNG2?usp=sharing
(The intention is to give read rights to all with the link)

#7

From my exiftool output:

Rendering Intent                : Perceptual
Profile Description             : RTv4_Medium
#8

Yes, I see the same thing, in the tiff file.

I think, but I do not know that this is picked up from RTv4_Medium.icc output profile which has “Rendering Intent : Perceptual”, or from the working profile RTv4_Large.icc which also has “Rendering Intent : Perceptual”.
(in post number 2).

Should this be “relative colorimetric” instead, since I choose this intent when I created the TIFF file? Or “perceptual” is the de facto standard for printing AdobeRGB (RTv4_Medium.icc) and is therefore the default. A user who want to change this has to edit RTv4_Medium.icc Rendering Intent default?

#9

I am uncertain if this answers your question:
https://rawpedia.rawtherapee.com/Preferences#Rendering_Intents.

Also see:
https://ninedegreesbelow.com/photography/icc-profile-conversion-intents.html