About image formats

The file format you choose for an optimized image is determined by the color, tonal, and graphic characteristics of the original image. In general, continuous-tone images such as photographs should be compressed as JPEG files. Illustrations with flat color or sharp edges and crisp detail, such as type, should be compressed as GIF or PNG-8 files.

PNG-24 file format is suitable for continuous-tone images. However, PNG-24 files are often much larger than JPEG files of the same image. PNG-24 format is recommended only when working with a continuous-tone image that includes multilevel transparency. (Multilevel transparency is supported by the PNG-24 format but not the JPEG format. See Preserving multilevel transparency in PNG-24 images.)

Depending on the format, you can specify image quality, background transparency or matting, color display, and downloading method.

The appearance of an image on the Web also depends on the computer platform, color display system, operating system, and browser used to display the image. Preview images in different browsers on different platforms and with different color bit depths to see how the images will appear on the Web.

Images and Page Design > About image formats

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