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

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 15 Jul 2010 18:36:05 -0700
Message-ID: <AANLkTilR5KVvEB1ThHy-PlFbcH5_By_SwXd-B-EgGqLx@mail.gmail.com>
To: Brad Kemper <brad.kemper@gmail.com>
Cc: Aryeh Gregor <Simetrical+w3c@gmail.com>, "L. David Baron" <dbaron@dbaron.org>, Simon Fraser <smfr@me.com>, Brendan Kenny <bckenny@gmail.com>, www-style list <www-style@w3.org>
As a contribution to the discussion, here's a hand-rolled
implementation of gaussian blur you can play with to get a sense for
how exactly it works.


It appears that just halving the length gives a good sigma for lengths
40px or less, but that approximation gradually becomes worse as the
blur gets larger (you gradually want something larger than half the


(By the way, I can see why gaussians are so sucky to work with.  I was
getting detectable floating-point errors nearly the entire time, which
were visible to the naked eye once the stdev topped 30 or so.  I had
to contort my computations to keep decent accuracy.)
Received on Friday, 16 July 2010 01:36:58 UTC

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