Following up on this original question & response

We are using a pre and post treatment design to measure the impact of dietary supplements on color. Originally, my plan was to use a PCA to simplify normalized %RGB and Brightness into a single variable (PC1) (see Nokelainan et al. 2019, DOI: 10.1111/1365-2435.13280). However, I am also curious about using CIE l*a*b because that is what studies with similar goals have chosen to use.

I have collected normalized %RGB values from ROIs of different body regions in multispectral images created in micaToolbox (using a single grey standard and black point estimates, same camera & lighting set up indoors). Is there a package in R, or suite of equations, I can use to determine l*a*b from the %RGB scores I gathered in micaToolbox? If I understand correctly, I think I could have done that while in imageJ, but I am hoping there is an option that doesn’t involve reanalyzing the images.

Convert from normalized %RGB to CIE L*a*b?
jolyon Answered question September 10, 2022