Compresses the image using JPEG compression.
JPEG compression can be used on RGB, Grayscale or CMYK images.
It offers high compression levels for continuous tone images like
photographs. However it is a lossy method which means that the
quality of the compressed image will not be as good as the
The quality of the compression can range from zero (lowest
quality, highest compression) to 100 (highest quality, lowest
compression). A good generic value is 75.