Description: Eight standard CCITT fax test images Keywords: graphics image CCITT fax compression Author: unknown Uploader: Stuart Inglis Uploaded-to: nic.funet.fi (13 Jun 1995) Handled-by: Kimmo.Ketolainen@ftp.funet.fi In the archive ccitt.tar, there are the eight CCITT fax test images. I have been informed that different researchers have scanned the official paper versions from the CCITT, so perhaps there is no definitive electronic version. Previous versions of these images have contained "right shifts" in the image, this is noticeable in image1 (top line of text) and image3 (bottom boxes on right). A little bit of background information from Langon & Rissanen, 1981 IEEE Trans. of Communications, pg. 858-867, PART F: Compression Results. "The test documents were provided by the French PTT to the CCITT Study Group XIV for the purpose of comparing compression algorithms. The documents are scanned with a nominal resolution of 8 pels/mm (~200dpi), which amounts to 1680 pels per text line. By addition of white margin to the right this was extended to 1728 pels, and with 2376 pels in the vertical direction the entire page gives a total of 4 105 728 pels." Compression ratios for various methods include (total compression over all eight images) CCITT G4 15.5 : 1 JBIG 18.2 : 1 Q-Coder 19.0 : 1 (1) 2 level coding 21.4 : 1 (2) TIC 21.6 : 1 (3 -- 22.3 : 1) (1) "Probability estimation for the Q-Coder", W.B. Pennebaker and J.L. Mitchell, IBM J. Res. Develop., Vol 32, No 6, 737-752, Nov 1988. (2) "Textual Image Compression; Two-Stage Lossy/Lossless Encoding of textual Images", Witten, Bell, Emberson, Inglis, and Moffat, Proc. of the IEEE, Vol 82, No 6, 878-888, June 1994. (3) Same source as (2) refined from 21.6 to 22.3 : 1 by the author. Stuart Inglis singlis@cs.waikato.ac.nz