Reduce png image size

OptiPNG allows you to reduce the size of a png assets and it does this without doing any quality.

You would normally execute it:

optipng -o7 some-image.png

But if you want to do the command automatically for all png images in a folder, you can use the find command to help you.

find -name '*.png' -exec optipng -o7 '{}' \;

This command is more than enough. Parameter -o7 is already incading the best compression. But you can tweak a little the command and hope that brute force could lower even more the final image. Just add -zm1-9 (Note: this can be very slow, just leave it running during the night). Finally add --strip all to remove extra metadata.

You are left with the command:

find -name '*.png' -exec optipng -o7 -zm1-9 --strip all '{}' \;

Normally i add the -preserve argument, so to avoid changing the file attributes if it didn’t change. So my final, ultimate png image reduction command is:

find -name '*.png' -exec optipng -o7 -zm1-9 -preserve --strip all '{}' \;