Comments on: pngcrush – PNG optimizer utility in openSUSE

By: Javier

Javier — Mon, 19 Oct 2009 14:08:48 +0000

Does anybody know a decent tool for reducing .jpg files (preferibly converting them to png). I’ve checked optipng out but its supported external files does not include .jpg. I need a reduction as lossless as possible.

By: dominiko

dominiko — Sun, 01 Mar 2009 09:39:04 +0000

> is there a way to keep the tags with pngcrush?

Can you try with optipng instead of pngcrush?
See http://optipng.sourceforge.net/

optipng does not lose any information as far as I know.
I’m not sure what “digikam tag” is, but I assume that’s
a comment in the image (which should not be removed by
optipng).

By: biomimetics

biomimetics — Sun, 01 Mar 2009 07:39:41 +0000

if i have a digikam tag in the image just using “pngcrush image_with_tag.png crushed_image.png” will result in the loss of my digikam tag, which is not so nice. all digikam settings are set to save the addition informaiton in the file. so if I just copy my image the tag shows up nicely in digikam. is there a way to keep the tags with pngcrush?
best regards robin

By: dominiko

dominiko — Thu, 19 Feb 2009 18:27:42 +0000

It is also possible to reduce size of png images using imagemagick in a lossy way (but often not noticeable) and then running optipng or pngcrush as a last step:

For example:

# Reduce depth to 4 bits and strip comments with
# imagemagick command line, then run optipng
$ convert -strip -depth 4 foo.png foo.png
$ optipng -o9 foo.png foo.png