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Re: Proposal: feHSL element (was Re: [filter-effects] hue-rotate() and saturate() filters)

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 15 Oct 2013 10:28:40 -0700
Message-ID: <CAAWBYDDMMj2NAojOC6E_=N+9mX+Lzf1eL9OabdtYSH=Qc9Lpfg@mail.gmail.com>
To: Chris Lilley <chris@w3.org>
Cc: FX <public-fx@w3.org>
On Tue, Oct 15, 2013 at 9:02 AM, Chris Lilley <chris@w3.org> wrote:
> Here is a proposal for a new feHSL element which performs hue rotation
> and saturation changes without suffering from internal clipping. Due
> to filter effects clipping after each primitive, saturation increases
> will still suffer from clipping in a multi-stage pipeline.

I was going to comment that it seemed like you've have issues on the
the low end too (you lose the hue information), but it looks like you
can't recover from a 0 saturation in a later filter, as you only have
multiplicative adjustments.  (My color adjusters in Colors 4 can do
additive adjustments to saturation, so I keep the hue information
around when possible.)

> I didn't provide for any operations on the L axis of HSL because
> operations on lightness or luminance are already available by other
> means.

Even if they are available by other means, I think it's worthwhile to
reproduce them here, so that you have a complete and
easy-to-understand interface.

Received on Tuesday, 15 October 2013 17:29:26 UTC

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