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To: Felix Niklas <mail@felixniklas.de>, internals@lists.php.net
References: <BEAB2910-EABC-410D-95FF-583A69EF4623@felixniklas.de>
Cc: Pierre Joye <pierre.php@gmail.com>
Message-ID: <9ca7ed2b-0b82-dfae-2d2a-aacf6913414b@gmx.de>
Date: Wed, 28 Sep 2016 12:34:07 +0200
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Subject: Re: [RFC] add radius and sigma to IMG_FILTER_GAUSSIAN_BLUR
From: cmbecker69@gmx.de ("Christoph M. Becker")

On 28.09.2016 at 10:09, Felix Niklas wrote:

> tl;dr: I’d like to add the parameters radius and sigma to the
> $filtertype IMG_FILTER_GAUSSIAN_BLUR by switching the underlying
> libgd method from <gdImageGaussianBlur> (accepts no parameters) to
> <gdImageCopyGaussianBlurred> (accepts these parameters).

I agree that gdImageCopyGaussianBlurred() should be preferred over
gdImageGaussianBlur(), at least in theory (not sure if
gdImageCopyGaussianBlurred() is sufficiently well (field-)tested).

The question is whether this should be done by the PHP binding, or in
libgd itself, where a comment for gdImageGaussianBlur() already states:

| Future versions of this function may fall back to calling it
| [gdImageCopyGaussianBlur()] instead of <gdImageConvolution>, causing
| subtle changes so be warned.

Either way, a user preferring the "classic" implementation could easily
use gdImageConvolution() and imageconvolution(), respectively.

Anyhow, even if we adjust the PHP binding only, the RFC process might
not be necessary; instead a PR might be sufficient.

-- 
Christoph M. Becker