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Re: [css3-background] Where we are with Blur value discussion

From: L. David Baron <dbaron@dbaron.org>
Date: Tue, 13 Jul 2010 17:24:24 -0700
To: www-style@w3.org
Message-ID: <20100714002424.GA7253@pickering.dbaron.org>
On Wednesday 2010-07-14 02:06 +0200, Bjoern Hoehrmann wrote:
> David is just arguing to prefer re-use over re-invention. If there is
> some well-known mechanism, and that mechanism is described using well-
> known terms, then it is preferable to use that mechanism and describe
> it in those terms, over coming up with new, unproven mechanisms and
> terms, unless that is shown to be necessary. He is not arguing to de-
> fine something by saying "Do this like Photoshop does that", or "Do
> this as if you were using Cairo and called function X and then Y.".
> 
> At least as I understand him, there is no reason to expect readers of
> the specification will have difficulty predicting the dimensions of
> the shadow knowing the radius parameter and the specification but not
> some particular graphics library, due to following the advice above.

Yes, that's what I was trying to say.

See, for example, http://en.wikipedia.org/wiki/Gaussian_blur , which
uses the term "radius" as the characteristic of a blur twice, but
doesn't use the term "distance" as the characteristic of a blur
(though it does use "distance" in other contexts).  That article
doesn't, however, explain how the radius relates to the σ of the
Gaussian function.

(I'm not saying "radius" is the only term already in use.
http://www.w3.org/TR/SVG11/filters.html#feGaussianBlurElement
describes blurs in terms of the standard deviation of the Gaussian
function.)

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Wednesday, 14 July 2010 00:24:53 GMT

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