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Re: [css3-transitions] colour space used for colour interpolations

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 24 May 2012 13:47:57 -0700
Message-ID: <CAAWBYDAdHb1WiVUfdubNdJMgHRn2aMsTT05m6Otj91OZfSV3GA@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: Cameron McCormack <cam@mcc.id.au>, "www-style@w3.org" <www-style@w3.org>
On Thu, May 24, 2012 at 9:44 AM, Rik Cabanier <cabanier@gmail.com> wrote:
> Reading a bit more on the wikipedia article [1] on HSL, I came across the
> following quote:
>
> Because hue is a circular quantity, represented numerically with a
> discontinuity at 360°, it is difficult to use in statistical computations or
> quantitative comparisons: analysis requires the use of circular statistics.
> Furthermore, hue is defined piecewise, in 60° chunks, where the relationship
> of lightness, value, and chroma to R, G, and B depends on the hue chunk in
> question. This definition introduces discontinuities, corners which can
> plainly be seen in horizontal slices of HSL or HSV.
>
> I believe it doesn't make sense to transition in HSL because of these issue.
> Who would want to create such a synthetic transition?

Heh, who would ever want to transition in RGB?  It's infinitely worse. ^_^

Ultimately, what matters is what the system graphics libraries
support, or can be extended to support.  HSL is a pretty shitty
colorspace, but it's simple to work with, and way better than RGB for
most things.  If we can convince the implementors working on graphics
to do a better colorspace, awesome, but if we can't, falling back to
HSL is acceptable in my mind.

(The major problem with HSL, more than anything else, is that there's
no analog of "premultiplied" colors like RGBA has, so transitions
to/from 'transparent' are going to be ugly.  I don't think any of the
better colorspaces have a solution to this either.)

~TJ
Received on Thursday, 24 May 2012 20:48:48 GMT

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