Stream Compression Filter: PDF files store most of the embedded data (such as page descriptors, fonts) in streams. All streams in the document support compression. Setting stream compression formats effects documents the most which use lots of text or 2D vector-graphical content and few raster images
Monochrome Image Compression: Different compression formats may be used specially for 2 color image formats, i.e.: the CCITT Fax compression format, which offers a great compression ratio but only for monochrome raster images.