Support for Preferences.jl

[kimikage]

There are several arguments, mainly in color definitions and conversions.
On the other hand, satisfying all preferences is unaffordable in this package. Perhaps that is the job of a color management system.

I think we can reflect preferences on the issues of default value which we already have specifically.

The possibilities are:

• Default whitepoint

  • Colors.jl/src/cie_data.jl

    Line 16 in f0a508b

    const WP_DEFAULT = WP_D65

• Default CMF (not very important, but affects the drawing of chromaticity diagrams.)

  • Colors.jl/src/colormatch.jl

    Line 38 in f0a508b

    return colormatch(CIE1931_CMF, wavelen)

• Default max size of swatches

  • Colors.jl/src/display.jl

    Line 7 in f0a508b

    const default_max_swatches = 128 * 128

• Default diff. metric

  • Colors.jl/src/differences.jl

    Line 452 in f0a508b

    metric::DifferenceMetric=DE_2000()) = _colordiff(ai, bi, metric)

Again, do not try to satisfy all preferences. That will obviously spoil this package.

[kimikage]

There was (is?) some discussion about chromatic adaptation, but since no one has made a specific proposal, I have decided that it is the job of color management systems.
cf. #278, JuliaGraphics/ColorTypes.jl#294

[kimikage]

As for the YCbCr preference issue, in about 2020 I tried to solve it with a separate package.
https://discourse.julialang.org/t/pre-rfc-ann-color-related-packages-yuvcolortypes-cmykcolortypes-colorprofiles-hdrcolortypes-hdrimages/113032
The fact that the problem has not been resolved after four years makes it understandable that we SHOULD NOT try to accommodate preferences easily.

cf. #453, #372