This image contains 12 megabytes of data. A color brochure with a dozen such images can easily soak up 150MB on your hard disk, and can be practically impossible to send elsewhere via modem. This column discusses the problems related to photo file size and one solution, JPEG compression. The common problems For many of us, large photo files become a problem when they fill up expensive hard disks or when we need to send the images to a service bureau. You can put large amounts of data on several types of portable disks, but copying large files takes time and the special disks and drives are expensive.
Large photos are also incompatible with modems.
A 12MB color photo like the one described above can take hours to transmit, tying up the transmission lines for both you and your recipient. You can reduce the resolution of images for transmission, but down-sampling alone is seldom enough. JPEG generally doesn't work well with illustrations, flat-color files, or files that contain type. Compression packs data tighter in a saved file. When a compressed image file is decompressed for viewing or printing, it regains its original size.