[TYPO3-core] RFC #8878: Bug: Fix cropscale behaviour for transparent GIF

[Jigal van Hemert]

Hi,

On 8-8-2010 15:46, Steffen Ritter wrote:
> Since we require gd2 we probably should have a look in what we can do
> without an external tool at all... in sprite-generator I found out that
> the gd variant was much faster than external tools.

I think that you'll find out that GD is very limited in its 
possibilities and that it is not very easy to obtain good results with it.

I'm currently trying to make GD produce transparent PNGs with an alpha 
channel, but this proves to be rather complicated.
Transparency is handled either as "combine both pixels with full 
transparency, but the result is fully opaque" or as "overwrite the 
original pixel, but keep full transparency".

You can apply a matrix to an image to get effects like blur, unsharp 
mask, but these are limited to a 3x3 matrix (imageconvolution).

Also the quality of resampling is not as good as the various advanced 
algorithms in IM/GM can produce.

-- 
Jigal van Hemert
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msn: jigal at xs4all.nl
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