There are also online tools which can help you optimize your pictures with loss of quality, by performing safe automatic tasks:
- Yahoo! Smush.it is the most well-know: http://www.smushit.com/ysmush.it/
- Kraken is another which at times can give better results, and has Firefox and Chrome extensions: http://kraken.io/
- Image Optimizer enables you to also change the size of the file: http://www.imageoptimizer.net/
If you are at ease with command line tools, you can use these:
-
Pngnq: converts 24-bit PNG files into 6 to 8-bit ones, by only keeping the needed colors. Download: http://pngnq.sourceforge.net/ Sample command line:
pngnq -vf -s1 image.png -
OptiPNG: tests several compression methods on a PNG file in order to find the best one. Download: http://optipng.sourceforge.net/ Sample command line:
optipng -o7 image-nq8.png -
pngcrush: another PNG optimization tool. Download: http://pmt.sourceforge.net/pngcrush/ Sample command line:
pngcrush image.png -rem all -reduce -brute result.png -
jpegtran: performs lossless operations on JPEG images. Download: http://jpegclub.org/jpegtran/ Sample command line:
jpegtran -copy none -optimize -perfect src.jpg dest.jpg