Web images take up the majority of the download time in most Web pages. But if you optimize your Web images you will have a faster loading Web site. There are lots of ways to optimize a Web page. The one way that will improve your speed the most is by making your Web images as small as possible. However, this can be tricky. Striving to make your Web images no larger than 12Kb can be a big job. Here are a few tips to making large Web images smaller:
1.Is the Web image in the right format?
There are only two (or three) image formats for the Web, but each is built for a specific purpose.

JPEG
This format is for images with millions of colors, that have a more photo realistic look. In fact, you should use the jpeg format for photographs, and other images that have a lot of colors. The jpeg format is a "loss" format, so try to avoid editing and saving the same file over and over again, as the images will lose quality. How many colors does your GIF use?
Saving a three color file as a 256-color indexed GIF will increase the size. When saving as a GIF, it's a good idea to convert the image first to Web colors (if you're using Photoshop, choose the image mode, indexed, and then choose Web colors). This will make sure that the colors won't dither on the Web. Then convert the image to the least number of colors it can use and still look correct.

2.GIF
This format is for images with a small, set number of colors. Most images created for the Web are created in GIF format. GIF images use an index of colors for the image, colors that are not used in the image, don't need to be included in the index. This format is good for images with a lot of flat color.
3.Is the Web image cropped?
If you have a photo on the Web, make sure that only the relevant parts are in the image. Cropping can make your Web image smaller both in dimensions and download size. It also helps clarify what is important in the image.
4.How many colors does your GIF use?
Saving a three color file as a 256-color indexed GIF will increase the size. When saving as a GIF, it's a good idea to convert the image first to Web colors (if you're using Photoshop, choose the image mode, indexed, and then choose Web colors). This will make sure that the colors won't dither on the Web. Then convert the image to the least number of colors it can use and still look correct.
Web images take up the majority of the download time in most Web pages. But if you optimize your Web images you will have a faster loading Web site. There are lots of ways to optimize a Web page. The one way that will improve your speed the most is by making your Web images as small as possible. However, this can be tricky.