This is a format for presenting fonts in PDF files that was initially conceived to store symbols in the Japanese and Chinese languages because it had a 16-bit structure and allowed for more precise adjustment. CID expands the the potential for PostScript by supporting languages that do not have a left-to-right orientation, and by supporting even a vertical mode of orientation.
This format is used to compress TIFF images when sending them via fax machines. This format helps reduce the data transmission time. Group 3 eliminates redundant data during compression in order to reduce file size. The standard 10:1 compression ratio may be increased to the user's preferences, but it can lead to a significant loss of image quality.