PDF (adobe.com)

Optimize JPEGs

Using the Optimize panel, you can optimize JPEGs by setting compression and smoothing options.

JPEGs are always saved and exported in 24-bit color, so you can't optimize a JPEG by editing its color palette. The color table is empty when a JPEG image is selected.

As you experiment with different optimization settings, use the 2-Up and 4-Up buttons to test and compare a JPEG file's appearance and estimated file size.

Note: JPEGs can be saved directly from within the "Save As" dialog box.