[Image-SIG] Patch: Better compression of png-images

[Alexey Borzenkov]

On Wed, Jul 22, 2009 at 1:34 PM, Flynn Marquardt<pil at flynnux.de> wrote:
> Reverting this to:
>
>                err = deflate(&context->z_stream, Z_NO_FLUSH);
>
>                /* FIXME: temporary workaround for problem with recent
>                   versions of zlib -- 990709/fl */
>
>                // err = deflate(&context->z_stream, Z_SYNC_FLUSH);
>
> improves the compression (close) to the desired optimum. I think the
> mentioned bug in zlib is fixed, it is ten years ago.

No, it appears it is not. I tried working with PIL compiled with
Z_NO_FLUSH and several hours later I found that it rarely generates
corrupt png images. And this is with zlib 1.2.3, so it appears it is
either not fixed, or there is something else going on...