Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

LMS conversion using CAT02 is questionable #294

Closed
ATell-SoundTheory opened this issue Nov 13, 2023 · 1 comment
Closed

LMS conversion using CAT02 is questionable #294

ATell-SoundTheory opened this issue Nov 13, 2023 · 1 comment
Labels
downstream Colors.jl, ColorVectorSpace.jl, etc.

Comments

@ATell-SoundTheory
Copy link

Using the CAT02 conversion matrix used for converting CIE 1931 XYZ to LMS is not really meaningful without the required post processing steps (see the wikipedia article you linked). The transform also assumes a standard illuminant E whitepoint and not a D65 one, which I think you are implicitly using. Adding this to the documentation would also be helpful.

As a result, converting spectral color matching results to LMS results in negative color coefficients, which is impossible because these values are defined as non-negative receptor stimuli.

In general, it would be wise to mark the XYZ type with the CIE standard that is used, because this standard also determines the proper way to convert to LMS or which color matching function from Colors.jl is the fitting one.

Therefore, at the moment, there is no correct native workflow for converting spectral colors to XYZ and to LMS.

@kimikage
Copy link
Collaborator

kimikage commented Apr 3, 2024

Color conversions are the domain of Colors.jl, not ColorTypes.jl.
I once tried to expand on chromatic adaptation. However, I decided it was better to have a separate package for color management.
cf. JuliaGraphics/Colors.jl#340

@kimikage kimikage added the downstream Colors.jl, ColorVectorSpace.jl, etc. label Apr 23, 2024
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
downstream Colors.jl, ColorVectorSpace.jl, etc.
Projects
None yet
Development

No branches or pull requests

2 participants