Some browsers render PNG images with color profiles and other shenanigans, some don't.

The cleanest way to have consistent colors across browsers is to convert all your images to a standard color profile, strip the image's original profile and attach the standard profile.

If you can't be bothered to convert color profiles, a quicker (but less effective) method is to remove some PNG chunks from your files.

With Geordi

Geordi Show archive.org snapshot brings a command png-optimize which conveniently optimizes your PNGs for the web. See Github for a description

• Single file and batch optimization is supported
• png-optimize will overwrite the original files

Without Geordi Show archive.org snapshot

Linux:

sudo apt-get install pngcrush

• Single file:

  Copypngcrush -rem alla input.png output.png
  

• Batch processing (will put the files into a "fixed" directory):

  Copypngcrush -d fixed/ -rem alla *.png
  

Windows:

Use TweakPNG Show archive.org snapshot

Mac:

Use ImageOptim Show archive.org snapshot

More info about pngcrush

Copypngcrush -rem allb -reduce -brute original.png optimized.png
pngcrush -d target-dir/ *.png

• -rem allb: remove all extraneous data (except transparency and gamma; to
  remove everything except transparency, try -rem alla)

• -reduce: eliminate unused colors and reduce bit-depth (if possible)

• -brute: attempt all optimization methods (requires MUCH more processing time
  and may not improve optimization by much)

• original.png: the name of the original (unoptimized) PNG file

• optimized.png: the name of the new, optimized PNG file

• -d target-dir/: bulk convert into this directory target-dir

• -rem cHRM -rem sRGB -rem gAMA -rem ICC: remove color profiles by name (shortcut -rem alla)

An article explaining why removing gamma correction: http://hsivonen.iki.fi/png-gamma/ Show archive.org snapshot