[cl-gd-devel] PNG compression

[Hans Hübner]

2008/10/2 Andrei Stebakov <lispercat at gmail.com>:
> Yes, it works.
> The scenario that I have is like this:
> I am trying to down-size a png image so I
>
> open it with with-image-from-file
> copy resized image (copy-image old-image new-image ....)
> save it  (write-image-to-file new-image-file-name :image new-image
> :compression-level 5)
>
> In my case :compression-level doesn't change the size of the output image.
> Probably it happens because the original file that I am trying to re-size is
> already compressed to the maximum.

I fear I don't know enough about PNG compression to say anything
profound here.  I do suspect that it is a general GD issue rather than
a cl-gd problem, so maybe asking on some GD support channel would be
helpful?  You'd propably need to supply the image in question to have
someone comment on what compression you can expect.

-Hans