To speed up image download and reduce the amount of bandwidth used, you need to optimize your images for on-line viewing. That is done by reducing the file size of your images (not necessarily reducing the dimensions of the image itself, but the amount of hard drive space the image file uses). Take, for example, a photographic image that is 512k in size. For users that access the internet through a dial up connection, your image will take anywhere from 5 to 10 minutes to download. However, if you first optimze the image, which could likely reduce the image to less than 50k in size, this same image will take only seconds to download for these same users.
This will also save a tremendous amount of bandwidth which could save you money if your site goes beyond the included allotment. For example, if 5000 visitors view your 512k image, it will use 2500MB (2.5 gig) in bandwidth. As you can see, that could quickly use up the bandwidth included with your site. On the other hand, if 5000 visitors downloaded an image that was 50K in size, it would only use 250MB (.25 gig) of your bandwidth.
If you are using a tool like PhotoShop to create your images, it has built in support for reducing your image file size when you save it. However, if your graphics program does not offer this feature, there are on-line tools that will also work, such as the image optimizer offered by NetMechanic
When reducing photographs, it's usually best to keep the images in JPEG format as you can shrink them considerably with almost no loss in image quality. For example, take a look at the two images below. The first image shows a photographic image before optimization and is over 300k. The second image is the same photographic image after being optimized by NetMechanic
and is only 27k.
The image above is 300k.
After NetMechanic optimization it is only 27k.