I have a RAW image of a colour checker chart (NOT the Xrite passport but instead a Spyder checkr24) and an identical Jpeg which I have checked is not overexposed. When I generate the multispectral image, I’m claiming to have the standard reflectances 5,95 (I’ve also tried with other numbers here but getting the same issue). I then choose ‘measure chart’ with this image and save the results.
The issue arises when I try ‘generate cone mapping model from chart’ using these saved results. I’m selecting Bluetit 400-700 and D65 400-700, along with the default Xrite passport 400-700 spectra (this is the only option I have currently). I then get an error message saying ‘duplicate command: multiple regression, duplicate command: RGB exposure test, duplicate command: XYZ to CEILAB 32bit’ and my R squared results are horrible (0.69, 0.58 and 0.72).
Is my issue that I’m claiming the incorrect standard reflectances when generating the multispec image? Or perhaps I need to create a custom relfectance list to select instead of the Xrite passport when generating the cone mapping model? If so, is there a way I can show the toolbox my chart photo and get it to tell me what my reflectances are please?
Many thanks for your help,
Sy, not Jolyon BUT my hunch is, yes, you’d need to obtain reflectance measurements of your standard. An easy way (rather than using a spectrometer) would be to reference your standard against something (i.e. a spectralon standard) that you know the reflectance values for each channel (R/G/B).