Re: [GD-DEVEL] Changing png compression (level) in gdImagePngPtrEx doesn't affect the result...

hi Andrew,

On Tue, Oct 7, 2008 at 11:07 PM, Andrei Stebakov <[email protected]> wrote:
> I am using LibGD from the lisp environment (cl-gd) and I have problems
> compressing png files when I create a new image by copying a part of
> original png file.
> What happens under the lisp wrapper is a sequence of gdImageCopyResampled
> and gdImagePngPtrEx.
> If I vary the level variable from 0 to 9 (which is called "compression" in
> lisp wrapper) the size of resulting png image stays the same.

The compression level (or quality) does not change the size in a
significant manner. What I added to php's gd is the optional custom
PNG filter option, they drastically reduce the size of the given
image. You can see some explanations and tests here:

http://blog.thepimp.net/archives/imagepng,-take-2.html

It is on our todos to port these additions to 2.1.

Cheers,
-- 
Pierre
http://blog.thepimp.net | http://www.libgd.org