To make web pages load faster, one of the main things we should do is to optimize images. Optimizing is using methods to make images in gif, jpg and png formats have less size, without loss in quality.
The first thing to do is to select the correct format for saving images in. Pictures usually have better quality and less size in jpg format, while web graphics should be saved in png or gif format.
Then we need to optimize the image before saving. That is what quality of image is good enough, and of course less quality means less size. This is usually done in save for web & devices in photoshop.Then it's time for optimizing tools. After saving images, we can use tools to lower the size of images without loss in quality.
There are many tools for this, but I've selected the tools that I use myself and feel more comfortable with, and do good optimizaton.
Optipng for png format
The opensource tool that does optimization for png files very good. To optimize an image, we first need to open the command prompt. It's easier to copy optipng.exe to the folder of images and delete it after optimization is done. Now with a command like this, my.png is optimized with maximum optimization.
optipng -o7 my.png
Website: http://optipng.sourceforge.net
jpegtran for JPEG format
This is run under command prompt too. jpegtran writes the result in output. So if we want to save it in a jpg file, we can simply put a > after the command and enter a file name. The result will be saved in that file.
Sample command:
jpegtran -copy none source.jpg > destination.jpg
Website: http://sylvana.net/jpegcrop/jpegtran
Supergif for gif format
This program has a GUI unlike the two other.
website: http://www.boxtopsoft.com/supergif.html
Smushit, online optimization
If your site is online, and you want to optimize all it's images, you can use a nice tool names smushit which is now part of yslow which is an addon for Firebug, itself and addon for firefox.
To use it, first add yslow to firefox, go to tools, then select All smush.it
yslow for firefox: https://addons.mozilla.org/en-US/firefox/addon/5369
