Support for YCrCb?

[philtomson]

Is YCrCb equivilent to LAB or LUV or is it completely different? I'm working on translating an image processing algorithm which used YCrCb to Julia.

[timholy]

There's already (very limited) support for YCrCb in Images. I wasn't sure if it was interest to Color folks (it's really more about image transmission than color representation).

[philtomson]

Do you have an example of doing a conversion to/from YCrCb in Images?

On Sat, Dec 20, 2014 at 1:03 PM, Tim Holy notifications@github.com wrote:

There's already (very limited) support for YCrCb in Images. I wasn't sure if it was interest to Color folks (it's really more about image transmission than color representation).

— Reply to this email directly or view it on GitHub https://github.com/JuliaLang/Color.jl/issues/74#issuecomment-67749632.

[timholy]

Check the code in src/colortypes.jl

[philtomson]

@timholy: thanks. I was thinking this was a Color.jl issue, but in reality you're taking care of it in Images.

[timholy]

Well, perhaps it would be better here, but I was worried that it wasn't a "real" colorspace and might infringe on the core mission of Color, which is good colorimetry. One of the color experts here might comment, though---I'm happy to move any/all pieces of Images/src/colortypes.jl over to Color, if desired.

[m-lohmann]

I think adding the YCbCr color spaces, or even other video-related color spaces to Color is fine. We already have stuff for generating palettes, which isn’t exactly pure colorimetry either. I would say adding more color spaces does not counteract correct colorimetry.

[timholy]

Sounds good, I'll migrate it over.

Just to give you the whole perspective, Images/src/colortypes also includes several other color types/features, most of which are designed to work with images where the raw data is stored in a different internal format than expected by Color:

• An AlphaColor type where the alpha channel comes first in the immutable (in contrast with AlphaColorValue where it comes last; if we decide to have both, perhaps AlphaColorValue should be renamed ColorAlpha)
• More AbstractRGB types:
  • BGR with a reversed storage order compared to RGB
  • RGB1 and RGB4, immutables with 4 elements (one of which is a dummy) encoding RGB values. In RGB1, the dummy is first; in RGB4, the dummy is last. OSX in particular seems to like to work with 4-byte colors, which work efficiently with OpenGL
• YIQ
• HSI
• Gray and GrayAlpha for monochrome

Want all of this? Some of it? None of it?