InDesign

JPEG (.jpg) files

The Joint Photographic Experts Group (JPEG) format is commonly used to display photographs and other continuous-tone images in HTML files over the web and in other online media. The JPEG format supports CMYK, RGB, and grayscale color modes. Unlike GIF, JPEG retains all of the color information in an RGB image.

JPEG uses an adjustable, lossy compression scheme that effectively reduces file size by identifying and discarding extra data not essential to the display of the image. A higher level of compression results in lower image quality; a lower level of compression results in better image quality, but a larger file size. In most cases, compressing an image using the Maximum quality option produces a result that is indistinguishable from the original. Opening a JPEG image automatically decompresses it.

Note: JPEG encoding, which can be performed on an EPS or DCS file in an image-editing application such as Photoshop, does not create a JPEG file. Instead, it compresses the file using the JPEG compression scheme explained above.

JPEG works well for photographs, but solid-color JPEG images (images that contain large expanses of one color) tend to lose sharpness. InDesign recognizes and supports clipping paths in JPEG files created in Photoshop. JPEG can be used for both online and commercially printed documents; work with your prepress service provider to preserve JPEG quality in printing.