connorgr / d3-cam02 Goto Github PK

Is this a typo? It causes for instance anything like jabcolor.copy() to suddenly produce JCh instances and not new Jab instances.

The current implementation of d3-cam02 implements JCh in CIECAM02 whereas Jab is implemented in CIECAM02-UCS. Is this necessary? Can CIECAM02-UCS be used for both?

Right now J is not equivalent in the two functions, which I think is likely to cause unintentional user error. I don't have enough color science expertise to know whether CIECAM02-UCS supports the same set of specifications as CIECAM02 (e.g., C, H, h, Q, M, etc.). Input with someone who is more familiar with color science would be tremendously helpful.

Some Jab and JCh colors that are far outside of displayable RGB end up registering as defined, and I don't know why. For example:

d3.jch(12,90,90).displayable(); // === true
d3.jch(12,90,90).rgb(); // "rgb(65, 30, 5)"

This is consistent with the Colorspacious Python library as well as Billy Bigg's C implementation. It looks like this may not be the case with the Colour Python package, but their implementation differs so much I haven't had time to do a comprehensive comparison.

It would be nice to have JCh interpolation available for creating color maps. This is a nicer method of interpolation when you want to have a smoother transition across chroma from one color to the next.

This is similar to Lab/Lch interpolation outputs. Here is a comparison of interpolation in Jab vs Lab vs Lch from a blue to green color:

When visualizing this interpolation difference between cartesian and polar adaptations of color space, the polar takes a more curved transition. This can sometimes yield more aesthetically balanced color maps. Here is a visualization from top-down in LAB color space for the same scales (interpolated to black and white as well).

Lab interpolation in Lab space is purely linear, whereas Lch interpolation in Lab has curvature. This same curvature from a JCh interpolation would be desirable to include in this d3-cam02 library.

when I use d3.jch(2, 63, 248)+'', I got rgb(255, 0, 255), like red, maybe this is a bug?

d3.rgb(d3.jab(0,0,0)) maps to NaN and similar issues for white, but exceeds the RGB gamut.