Image compression settings are predefined for monochrome, grayscale, and color images. JPEG2000 compression is not backward compatible with PDF 1.3. Full object stream compression is not backward compatible with PDF 1.3 or PDF 1.4. When you choose JPEG2000 as the compression algorithm, or tick the "Maximum Compression for all image formats", PDF Vista printer driver produces PDF results compliant with PDF 1.5 specification.

Compression Algorithm

For monochrome image, CCITT G4 is a general-purpose compression algorithm to produce moderest compression for most types of monochrome images.

For grayscale and color images, ZIP is a safe compression algorithm to retain the look and feel of the original images with large areas of single colors or repeating patterns. JPEG algorithm works well on grayscale or color images containing more detail than can be reproduced on-screen or in print. JPEG2000 is a quality lossless compression algorithm to provide additional advantages, such as more local details, progressive display.

Image Quality

When JPEG algorithm option is chosen, users can adjust the Image Quality slider bars for grayscale image and color image. The slider bar is preset on 80% percent, i.e., the image quality is preset to 80%. The top scale is 0% and the bottom scale is 100%. Users can set the image quality for grayscale and color images of their choice.

For color images with large areas of single colors or repeating patterns, such as screenshots, simple wallpapers, ZIP algorithm is the best choice to avoid lossyness that would be otherwise caused by JPEG algorithm with a relatively low image quality setting.

Maximum Compression

Object Level Compression is a new feature to consolidate small objects into streams that can then be efficiently compressed and result in PDF file of smaller size. To enable "Object Level Compression", tick the "Maximum Compression for all image formats" option in the Image tab.