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This is our First Principle of Image File Size Reduction: Use smallest image dimensions that will work with your layout. And likewise fewer images on page, fewer image pixels, therefore smaller page size.
Since GIF and JPEG image formats use different methods of saving image information, they tend to be better at showing some types of images and worse at showing others.
GIF images, since they are limited to 256 colors per image, are better at displaying images with large solid blocks of color and images with very small physical dimensions. The GIF format will produce smaller file sizes than JPEG for these types of images.
JPEG images are better at showing gradients or subtle changes from one color to another. Therefore JPEGs reproduce photographs very well, or any other image with gradations. The JPEG format will produce smaller file sizes for these types of images than GIF format will.
This is our Second Principle of Image File Size Reduction: Choose correct image format for image you are using. Most web pages will contain a combination of GIF and JPEG images.
Decreasing coding is called image compression. Both GIF and JPEG images can be compressed but process is different. In GIF images we try to limit number of colors, in a JPEG image we use software algorithms to remove redundant information from file.
Whenever we compress a file we will lose some image quality. We have to reach a balance between a small file size and acceptable image quality.
This is our Third Principle of Image File Size Reduction: Find least acceptable level of image quality. Most images can handle some compression with very little quality loss, and all images can stand more image quality loss and still be acceptable. Your job is to decide how much quality loss you can accept. In other words, lower quality, smaller file size.
GIF images can usually be reduced from 256 colors to 128 colors or less, fewer colors used smaller file size. JPEG images can almost always be reduced to a quality setting of 80% and frequently can be reduced down to as little as 15-30%. So when you use a higher compression level (smaller number) file size will be reduced. Experiment with image, try smaller and smaller settings until you find smallest setting that still displays an acceptable quality.
The fastest loading page will have no images and slowest loading page will be completely filled with full resolution images. If you work towards controlling your images using principles outlined above you will have a very lean web page that will load quickly and be viewed favorably by search engines.
George Peirson is a successful Entrepreneur and Internet Trainer. He is the author of over 30 multimedia based video training titles covering such topics as Photoshop, Flash and Dreamweaver. To see his training sets visit www.howtogurus.com