Optimization options for JPEG format


    JPEG is the standard format for compressing continuous-tone images such as photographs. Optimizing an image as a JPEG format relies on lossy compression, which selectively discards data.

    Illustration of Optimization settings for JPEG with these callouts: A. File format menu B. Compression Quality menu C. Optimize menu
    Optimization settings for JPEG A. File format menu B. Compression Quality menu C. Optimize menu

    Quality

    Choose an option from the Quality Level menu, or specify a value in the Quality text box. The higher the Quality setting, the more detail the compression algorithm preserves. However, using a high Quality setting results in a larger file size than using a low Quality setting. View the optimized image at several quality settings to determine the best balance of quality and file size.

    Optimized

    Select Optimized to create an enhanced JPEG with a slightly smaller file size. The Optimized JPEG format is recommended for maximum file compression; however, some older browsers do not support this feature.

    Progressive

    Select Progressive to create an image that displays progressively in a Web browser. The image will display as a series of overlays, enabling viewers to see a low-resolution version of the image before it downloads completely. The Progressive option requires use of the Optimized JPEG format.

    Note: Progressive JPEGs require more RAM for viewing, and are not supported by some browsers.

    Blur

    Specify the amount of blur to apply to the image. This option applies an effect identical to that of the Gaussian Blur filter and allows the file to be compressed more, resulting in a smaller file size. A setting of 0.1 to 0.5 is recommended.

    ICC Profile

    Select ICC Profile to preserve the ICC profile of the artwork with the file. ICC profiles are used by some browsers for color correction. This option is only available after you've saved an image with an ICC profile--it is not available for unsaved images. (See Setting up color management.)

    Matte

    Specify a fill color for pixels that were transparent in the original image:

    • Click the Matte color swatch and select a color in the color picker.
    • Choose an option from the Matte menu: Eyedropper (to use the color in the eyedropper sample box), White, Black, or Other (to use the color picker).

    Pixels that were fully transparent in the original image are filled with the selected color, pixels that were partially transparent in the original image are blended with the selected color.