I have a stacked TIFF image which was stacked from CR2 raw files from a Canon EOS 60Da. Daylight colour balance was applied to the CR2 files as they were de-bayered.
I plate-solved the image, and run background extraction.
I then ran SPCC Colour Calibration:
and all the stars turned blue
Hereās the log
Initializing FFTW multithreading support...
log: Welcome to siril 1.4.2 for windows (x86_64 mingw64) - GUI
log: Supported file types: BMP images, PIC images (IRIS), PGM and PPM binary images, RAW images, FITS-CFA images, Films, SER sequences, TIFF images, XISF images, JPG images, JPEG XL images, PNG images, HEIF images, AVIF images.
log: Setting CWD (Current Working Directory) to 'C:\Users\amonra\Pictures'
log: Parallel processing enabled: using 16 logical processors.
log: Color management active.
log: JPEG ICC profiles supported.
log: Preparing python virtual environment: C:\Users\amonra\AppData\Local\siril\venv.
log: Checking the python module is up-to-date...
log: Checking SPCC mirrors...
Failed to execute child process (Invalid argument)
log: Default FITS extension is set to .fit
log: Python module is up-to-date
Entering wrapping_idle for function 00007ff7941639f0
scripts: Error opening directory āC:\Users\amonra\AppData\Roaming\siril\scriptsā: No such file or directory
log: Searching for scripts in: "C:\Program Files\Siril\scripts"...
log: Loading script: Mono_Preprocessing.ssf
log: Loading script: OSC_Extract_Ha.ssf
log: Loading script: OSC_Extract_HaOIII.ssf
log: Loading script: OSC_Preprocessing.ssf
log: Loading script: OSC_Preprocessing_BayerDrizzle.ssf
log: Loading script: RGB_Composition.ssf
log: Adding core script to menu: Siril_Catalog_Installer.py
log: Adding core script to menu: GPU_Manager.py
Last available version: 1.4.2
Entering wrapping_idle for function 00007ff7941639b0
scripts: Error opening directory āC:\Users\amonra\AppData\Roaming\siril\scriptsā: No such file or directory
log: Primary SPCC catalogue set to: https://gaia.wheep.co.uk (3 working mirrors available)
Entering wrapping_idle for function 00007ff79413ec80
log: Gaia remote SPCC catalogue available, response 127 ms
Entering wrapping_idle for function 00007ff794140550
log: Local SPCC database repository is up-to-date!
Entering wrapping_idle for function 00007ff794140550
log: Local scripts repository is up-to-date!
Entering wrapping_idle for function 00007ff7941639b0
scripts: Error opening directory āC:\Users\amonra\AppData\Roaming\siril\scriptsā: No such file or directory
nb_elts_at_start: 0
nb_elts_on_exit: 0
Purging previously saved reference frame data.
log: Reading TIFF: 32-bit file NGC457.tif, 3 layer(s), 5176x3433 pixels
log: Plate solving image from local Gaia DR3 astrometry for a field of view of 1.53 degrees, using a limit magnitude of 14.40
log: Findstar: processing for channel 1...
log: Using 2000 detected stars from image.
log: Fetched 2327 stars from Gaia DR3 astrometry catalogue
sig=6.1155e-003 Nr=1144 Nm=1292 sx=6.8369e-002 sy=7.8871e-002
log: Up is +49.44 deg CounterclockWise wrt. N
log: Resolution: 0.888 arcsec/px
log: Focal length: 1161.59 mm
log: Pixel size: 5.00 Āµm
log: Field of view: 01d 16m 35.53s x 50' 48.00"
log: Image center: alpha: 01 19 41.753, delta: +58 16 58.126
log: Was 1.36 arcmin from initial value
log: Saved focal length 1161.59 and pixel size 5.00 as default values
log: Background extraction from red channel.
log: Background extraction from green channel.
log: Background extraction from blue channel.
log: Background with RBF interpolation computed.
log: Execution time: 728.54 ms
log: Primary SPCC catalogue set to: https://gaia.wheep.co.uk (3 working mirrors available)
Entering wrapping_idle for function 00007ff79413ec80
log: Gaia remote SPCC catalogue available, response 119 ms
log: Findstar: processing for channel 1...
log: Findstar: processing for channel 0...
log: Findstar: processing for channel 2...
log: Getting stars from local catalogue Gaia DR3 xp_sampled for SPCC, with a radius of 1.53 degrees and limit magnitude 15.13
log: Computing background reference with tolerance +2.00Ļ / -2.80Ļ.
log: Photometry radii set to 21.9 for inner and 31.9 for outer
log: Applying aperture photometry to 3478 stars.
log: 1777 stars excluded from the calculation
log: Distribution of errors: 1701 no error, 1542 not in area, 61 inner radius too small, 174 pixel out of range
log: SPCC Linear Fits
log: Image R/G = -0.121623 + 3.889202 * Catalog R/G (sigma: 0.250156)
log: Image B/G = 0.012009 + 1.312429 * Catalog B/G (sigma: 0.095300)
log: Found a solution for color calibration using 1701 stars. Factors:
log: K0: 0.436
log: K1: 0.812
log: K2: 1.000
log: The photometric color calibration seems to have found an imprecise solution, consider correcting the image gradient first
log: After renormalization, the following coefficients are applied
log: White balance factors:
log: K0: 0.436
log: K1: 0.812
log: K2: 1.000
log: Background reference:
log: B0: +7.59586e-003
log: B1: +2.51292e-003
log: B2: -1.49142e-005
log: Spectrophotometric Color Calibration succeeded.
Is there anything I can to do provide more information?