TYPO3 Core

Using optipng or pngcrush should strip the profile (http://en.wikipedia.org/wiki/Pngcrush#Reducing_filesize_by_removing_color-correction_data) ... maybe worth a try before going to gif.

Attached a zip with pngs stripped by gamma and profile information:

files=`find . -name *.png`
for file in $files
do
mkdir -p "typo3-new/`dirname $file`"
pngcrush -rem gAMA -rem cHRM -rem iCCP -rem sRGB $file typo3-new/$file
done