Website speed is important nowadays, for both the visitor and in the eyes of search engines. Reducing the size of the images is one of the first steps a webmaster should take when he starts making his websites load faster.
I usually use Yahoo! Smush.it to reduce the size of the images without changing their look or visual quality. However, for compressing PNG image files I’ve found a better tool called TinyPNG.
This online tool uses smart lossy compression methods to decrease the file size of your PNG files. By precisely decreasing the number of colors from the image, less bytes are necessary to store the data. The result is virtually invisible but it makes a substantial difference in file size!
The resulted images are displayed perfectly on all major browsers including mobile devices. Internet Explorer 6 normally disregards PNG transparency and shows a solid background color. With TinyPNG the background results in being transparent again. Binary transparency with no workarounds!
When you upload a PNG (Portable Network Graphics) file, similar colors in your image are combined. This technique is called “quantisation”. Because the number of colors is reduced, 24-bit PNG files can be converted to much smaller 8-bit indexed colour images. All unnecessary metadata is stripped too. The result: tiny 8-bit PNG files with 100% support for transparency. Have your cake and eat it too!
- Source: http://tinypng.org/