Optimizing JPEG Images
Years ago, a need was seen for an image file format that produces more lifelike, photographic images. The Joint Photographic Experts Group (JPEG) was formed to create standards, and today, we have a choice between GIF and JPEG when creating Web pages and emailing files to friends and family.
Unlike GIF, JPEG is a lossy compression file format. That is, image data that you might never see anyway is cast out of the image when the file is created. The Experts Group decided that the human eye is less sensitive to changes in tone than in color, and so by averaging tones, a “well-compressed” JPEG image can show little or no data loss over the original.
Figure 23.4 shows the Optimize palette in ImageReady when we decide on JPEG ...
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