wan@mercury (Shijie Wan) (04/22/91)
Color Compression Software Available ------------------------------------ A full-color image can use up to 16 million different colors. Most commonly used color monitors and laser printers can display/print only 256 or less different colors simultaneously. In order to display/print a full-color image on these devices, the number of colors in the original image must be compressed before display. We have designed a color image quantization algorithm which can reduce the colors in a full-color image to 256 colors or less with minimum distortion. Experiments show that in most cases our algorithm needs to use 128-256 colors to produce an image which looks almost identical to the original full-color image. With 32-64 colors, it can produce images of high quality. For 32 colors or less, it can generate quantized images with minimum contouring effects, with the aid of dithering techniques. For details of the algorithm and image examples, read the paper: S.J. Wan, P. Prusinkiewicz, and S.K.M. Wong, Variance-based color image quantization for frame buffer display, Color Research and Application, vol. 15 (1), pp. 52-58, Feb. 1990. The program is written in C for Silicon Graphics IRIS machine. Versions for other machines running UNIX are also available. Excluding the time for image disply, the program needs about 10-40 seconds to process one image. For more information, please contact: ---------------------------------------------------------------- | wan@mercury.uregina.ca | Shijie Wan | | Tel: (306)-584-5717 | Dept. of Comp. Sci. | | (306)-585-4690 | Univ. of Regina | | Fax: (306)-584-5717 | Regina, Sask. | | | Canada S4S 0A2 | ----------------------------------------------------------------
lee@mport.COM (Lee Crocker) (04/24/91)
wan@mercury (Shijie Wan) writes: > Color Compression Software Available > [Description of an implementation of the WWP vector quantizer.] There are several public domain sources for this algorithm, most of them based on an implementation by Craig Kolb. The FBM utilities is probably the best source for Unix. Piclab implements the algorithm for MSDOS. Both are available FTP from various graphics-oriented archive sites. -- Lee Daniel Crocker lee@mport.com (Microport) ...!uunet!mport!lee 73407.2030@compuserve.com
yeidel@tomar.accs.wsu.edu (Joshua Yeidel) (04/25/91)
There are three main approaches to making videotapes from computer screen:
1) point a video camera at the screen. Eye-boggling problems result,
including roll-bars and flicker.
2) Television-standard ("NTSC") video boards in the computer. May work well
for particular uses. Problems include being tied to one computer, and software
may need to be video-aware. Vendors include:
TrueVision, Inc.
7351 Shoreland Station, Suite 100
Indianapolis, IN 46256
(317) 841-0332
3) Scan-convert the computer's own video output to NTSC standard. This can
be done by outboard boxes with quite good quality (considering the inherent
limitations of NTSC). A wide range of prices and features are available.
Vendors include:
Qutron
Attn: Wayne Dengel
Post Office Box 105
Allendale, NJ 07401
(201) 327-3259
Fax: (201) 818-1963
Lyon Lamb Video Animation Systems, Inc.
4531 Empire Ave.
Burbank, CA 91505
(818) 843-4831
Electro Communication Systems, Inc.
2043 Empire Central
Dallas, TX 75235
(214) 358-5195
Folsom Research, Inc.
526 East Bidwell Street
Folsom, CA 95630
(916) 983-1500
Fax: (910) 997-0955
RGB Spectrum
2550 Ninth Street
Berkeley, CA 94710
(415) 848-0180
Fax: (415) 848-0971
James Grunder & Assoc., Inc.
5925 Beverly
Mission, KS 66202
(913) 831-0188
Fax: (913) 831-3427
Naturally, I have no connection with any of these vendors, nor should this list
be considered complete. It's just information I've come across in my work.
bdb@becker.UUCP (Bruce D. Becker) (04/29/91)
In article <1991Apr24.210116.24904@serval.net.wsu.edu> yeidel@tomar.accs.wsu.edu (Joshua Yeidel) writes: |There are three main approaches to making videotapes from computer screen: | |1) point a video camera at the screen. Eye-boggling problems result, |including roll-bars and flicker. | |2) Television-standard ("NTSC") video boards in the computer. May work well |for particular uses. Problems include being tied to one computer, and software |may need to be video-aware. Vendors include: |[...] |3) Scan-convert the computer's own video output to NTSC standard. This can |be done by outboard boxes with quite good quality (considering the inherent |limitations of NTSC). A wide range of prices and features are available. 4) Use a computer whose video system uses NTSC/PAL directly, like the Commodore Amiga (and its associated peripherals such as the Video Toaster). Software for such systems tends to take this ability as given, and thus is often more flexible and powerful when applied to a given situation. -- ,u, Bruce Becker Toronto, Ontario a /i/ Internet: bdb@becker.UUCP, bruce@gpu.utcs.toronto.edu `\o\-e UUCP: ...!utai!mnetor!becker!bdb _< /_ "The really important problems require greater earnestness" - J. Cage
craig@weedeater.math.yale.edu (Craig Kolb) (05/03/91)
In article <52@mport.COM> lee@mport.COM (Lee Crocker) writes: >wan@mercury (Shijie Wan) writes: > >> Color Compression Software Available > >> [Description of an implementation of the WWP vector quantizer.] > >There are several public domain sources for this algorithm, most of them >based on an implementation by Craig Kolb. The FBM utilities is probably >the best source for Unix. Piclab implements the algorithm for MSDOS. >Both are available FTP from various graphics-oriented archive sites. I should set the record straight by saying that, as far as I know, the Utah Raster Toolkit is the only package that incorporates my code. The credit for "fbquant" and whatever is implemented in piclab goes to their respective authors. The code I wrote, "colorquant", implements the algorithm described in: Wan, Wong, and Prusinkiewicz, An Algorithm for Multidimensional Data Clustering, Transactions on Mathematical Software, Vol. 14 #2 (June, 1988), pp. 153-162. Colorquant is available via anonymous ftp from weedeater.math.yale.edu as pub/colorquant.shar. The Utah Raster Toolkit is available from weedeater.math.yale.edu, freebie.engin.umich.edu, cs.utah.edu, and other archives sites. Cheers, Craig
lee@mport.COM (Lee Crocker) (05/04/91)
Having examined your code from the Utah Raster Toolkit and that from FBM, it is clear that the latter was based on your design. Having written the code in Piclab, I can state definitively that I based it on your design as well as the ACM paper. I did not use your code directly (indeed I could not as it required much more memory than MSDOS can handle), but I was definitely "inspired" by it. Piclab is available from cica.cica.indiana.edu and wsmr-simtel20.army.mil. -- Lee Daniel Crocker | "Computers are useless. They can only give lee@mport.com (Microport) | answers." --Pablo Picasso ...!uunet!mport!lee 73407.2030@compuserve.com