colour lib needs reviewers

[Marco Leise via Digitalmars-d]

Am Mon, 12 Sep 2016 14:14:27 +1000
schrieb Manu via Digitalmars-d <digitalmars-d at puremagic.com>:

> I think I'm about as happy with my colour lib as I'm going to be.
> It really needs reviews.
> 
> I added packed-RGB support, including weird micro-float and
> shared-exponent formats.
> They're important for interacting with any real-time rendering libraries.
> There is only one texture format I'm aware of that isn't supported,
> and that is u7e3 floats, only available on Xbox360 ;)
> 
> Chromatic adaptation functions are in.
> I've done a tidy/reorg pass.
> 
> I'm not sure what else should be in the scope of this lib.
> 
> PR: https://github.com/dlang/phobos/pull/2845
> dub: https://code.dlang.org/packages/color
> docs: http://dtest.thecybershadow.net/artifact/website-04a64e024cf75be39700bebd3a50d26f6c7bd163-7185c8ec7b15c9e785880cab6d512e6f/web/library-prerelease/std/experimental/color.html
> 
> - Manu

Nice work. What's u7e3? 3*10-bit-floats + 2-bit padding?

In the example for convert color you show that converting from
a color space without alpha (XYZ) to one with alpha (RGBA)
turns the pixel transparent. I believe you meant this as
something to lookout for when converting colors. What's the
reasoning for not setting maximum alpha as a more useful and
natural default?

Cool stuff there in the colorspace module, to get started with
getting photos or DV/MPEG into a linear color space. Should
BT.709 also have prefab conversion methods? It would seem HD
video is more wide spread nowadays.

There is a typo in "Function that converts a linear luminance
to gamme space." (colorspace.d)

I like how RGB color spaces are described as primaries in xyY
+ gamma functions.

It seems inconsistent that you can specify all kinds of
exponents when the exponent is shared but are forced to 5 bit
exponents when mixed into each component, while the mantissa
can still be adjusted. Would m7e3 have worked? (With f* being
the IEEE standard formats.)

The final package should contain a fair amount of
documentation, in my opinion also on the topics of sRGB vs.
linear and what "hybrid gamma" is.

What is your stance on pixel formats that are arranged in
planes? I assume that e.g. YUV is handled by a single channel
"sRGB luminance" + 2 signed 8-bit color planes? It may be
worth adding some hints in that direction.

All in all good work with a scientific feel to it.

-- 
Marco