Is it possible to use "SpyderCheckr 24" in RT?

Software RawTherapee
10

(Thread revival)

  • short answer, yes, it is possible with a few additional tools; I’m not saying it’s “easy” to evaluate the quality of the made profile, though
  • longer answer follows,
  • note: there are several colour checker manufacturers, other than Datacolor and Calibrite (X-Rite): see these examples

Hey, it’s 2022 and in the current dev branch of RT (5.8), I’ve just successfully imported a (poorly) processed Datacolor Spydercheckr 24 DCP for a specific purpose.

What I’m calibrating: nikon D750 + micro nikkor AF 60mm AF + CN-T96 LED light source (boxed in a Skier Sunray Copy box, meant as a backlight for scanning film).

I’ve just acquired the Datacolor target and spent a few hours making sense of the “basic” workflow that involves:

  1. argyllcms scanin module (source: homebrew)
  2. dcamprof (source: github)

What I’ve done (to get it to “work”) follows:

  1. take a “decent” shot (light at 45°, ETTR, straight, slightly defocused, etc.)
  2. in RT, open the raw file
    a. check raw histogram
    b. apply the Neutral profile to it,
    c. apply (if possible) Lens corrections (distortion, vignette, chromatic aberration)
    d. rotate it so the “white” patch (A1 in the description matrix used by argyllcms, 1E in the spydercheckr 48) is at the top left corner
    e. straighten shot
    f. crop with a bit of margin
    g. (I had glare) reduce glare slightly with a -0.20EV gradient filter
    h. save as reference image without white balance
  3. run scanin
  4. run dcamprof (make profile then make dcp)
  5. try to make sense of the console output (Delta E (written as DE), perceptual error)
  6. import newly made dcp in RT.

Command lines used (I’m on an M1 mac):

# output a .ti3 file we'll use in `dcamprof`
scanin -v -p -dipn rawtherapee_reference_image.tif /opt/homebrew/Cellar/argyll-cms/2.3.0/ref/SpyderChecker24.{cht,cie}

# output a `.json` profile we'll then use in `make-dcp`
~/programs/dcamprof/dcamprof/src/dcamprof make-profile -g ~/programs/dcamprof/dcamprof/data-examples/cc24-layout.json ~/Pictures/D750/spyderchecker_24/D750_60mm_CN-T96_20220625/nikon_D750_60mmAFD_CN-T96_spydercheckr24.{ti3,profile.json}

# output a dcp file we'll be able to import in RT
 ~/programs/dcamprof/dcamprof/src/dcamprof make-dcp -n "Nikon D750" -d "NikonD750_60mmAFD_CN-T96" -t acr ~/Pictures/D750/spyderchecker_24/D750_60mm_CN-T96_20220625/nikon_D750_60mmAFD_CN-T96_spydercheckr24.profile.{json,dcp}

Ref:

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