JPEG (Joint Photographic Experts Group)
JPEG compression is mainly used for photographic images. JPEG compression supports 24bit colour, which is why it is a good compression to use for photographic images with the thousands of colours necessary to make up the detail and smooth gradients of shadows and highlights in a photograph.JPEG compression is sometimes described as "lossy". This means that when an image is compressed using JPEG some of the information in the image will be disregarded. When you are making an image, always work on it as a PhotoShop file, BMP, PNG or a PICT file until the final stage. The last thing you do is to compress it as a gif or a jpeg. Always keep the original Pict/PhotoShop file in case you want to go back and make changes.
Note:
you will never achieve a perfect photographic image with a tiny file size - you will need to make a compromise between quality and file size. If you think of web graphics as a medium of their own and not as a photograph album you will soon find ways to make interesting images that enhance your web page without needing photographic quality and tedious download times.
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© 2002 Ashley Preston