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

From: Chris Lilley <chris@w3.org>
Date: Tue, 22 Oct 2013 16:08:51 +0200
Message-ID: <1613554907.20131022160851@w3.org>
To: Stephen White <senorblanco@chromium.org>
CC: Dean Jackson <dino@apple.com>, Dirk Schulze <dschulze@adobe.com>, Rik Cabanier <cabanier@gmail.com>, FX <public-fx@w3.org>
Hello Stephen,

Sunday, October 20, 2013, 11:56:30 PM, you wrote:

> I'd support a new element and shorthand.  Here are couple of comments:

> 1) Bikshed: feHSL suggests a colorspace, but this is really an
> operation within that colorspace.

Fair point.

>  Maybe feHSLOperation?
> feHSLTransform? feHSLTransformation? 

Happy to adopt whatever seems reasonable.

> 2) Is there a reason for using "hue" rather than "hueRotate"?

Brevity. But hueRotate is fine; what would you suggest for the
name of the saturation modifier?

> 3) If the L in HSL is computed differently than the luminance in
> feColorMatrix (which it would have to be to match CSS's HSL; someone
> can correct me if I'm wrong), then it would still be worthwhile to have a luminanceToAlpha type.

It is computed differently, yes (a really bizarre equal-weighting sum of R
G and B).

I responded to a similar suggestion in an earlier message. The value
of HSL is the polar (H and S) part. I suggested a couple of transforms
of HSL 'L' and concluded that they had significant issues.

> Stephen

> On Fri, Oct 18, 2013 at 2:46 PM, Dean Jackson <dino@apple.com> wrote:

>  On 19 Oct 2013, at 5:22 am, Dean Jackson <dino@apple.com> wrote:
 >> On 19 Oct 2013, at 3:59 am, Chris Lilley <chris@w3.org> wrote:
 >>> Hello Dirk,
 >>> Friday, October 18, 2013, 6:25:29 PM, you wrote:
 >>>> Hi Dean and Chris,
 >>>> I would like to clarify if you are both on the same side.
 >>>> So you both agree that we should have a new feHSL element?
 >>> Not speaking for Dino but I do, yes.
 >>>> You both agree that his primitive should operate in HSL regardless
 >>>> of the specified value of the 'color-interpolation-filters' property?
 >>> That is my proposal, yes.
 >>>> And you both agree that you do not want to fix hue-rotate() but
 >>>> create a new shorthand function for this new operation?
 >>> I could go either way on that one. I think the shorthand is more
 >>> recent, less widely deployed and there is less risk of breaking content
 >>> that uses it, so it should be safe to redefine it.
 >>> However, I would be persuaded by arguments that there is deployed
 >>> content and that a new shorthand (such as hue-rotate-hsl() for
 >>> example) should be created.
 >> ^^ This is what I meant: new feHSL and new shorthand hue-rotate-hsl.
>  BTW - I’m looking forward to seeing the complete math of this new effect.
>  (Crazy idea: wouldn’t it be cool if the spec had inline JS that
>  manipulated a <canvas> element via ImageBuffer? The spec could also be
>  the reference implementation.)
>  Dean

Best regards,
 Chris                            mailto:chris@w3.org
Received on Tuesday, 22 October 2013 14:08:56 UTC

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