Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!cbmvax!daveb From: daveb@cbmvax.UUCP (Dave Berezowski) Newsgroups: comp.graphics Subject: Re: 8x8 dither matrices Message-ID: <6727@cbmvax.UUCP> Date: 1 May 89 20:03:57 GMT References: <6717@cbmvax.UUCP> <2518@helios.ee.lbl.gov> Reply-To: daveb@cbmvax.UUCP (Dave Berezowski) Organization: Commodore Technology, West Chester, PA Lines: 37 In article <2518@helios.ee.lbl.gov> Jef Poskanzer writes: >In the referenced message, daveb@cbmvax.UUCP (Dave Berezowski) wrote: >} I now know how to generate >}ordered dither matrices of size power's of 2(ie. 2, 4, 8, etc.) BUT am >}still looking for references on Halftone dither matrices above a 4x4. > >I'm not completely sure what you mean by "Halftone". Halftoning is >the generic term for any sort of N-bit to 1-bit quantization. (Terminology >is great, isn't it?) Anyway, assuming you are talking about clustered >dithering of the sort used in newspaper photographs, here is an order-8 >45-degree clustered dither matrix: > > static int cluster8[8][16] = { > 65, 70, 78, 88, 87, 77, 69, 68, 64, 59, 51, 41, 42, 52, 60, 61, > 71, 95,101,110,109,100, 94, 76, 58, 34, 28, 19, 20, 29, 35, 53, > 79,102,115,117,116,113, 99, 84, 50, 27, 14, 12, 13, 16, 30, 45, > 89,111,124,125,126,119,108, 86, 40, 18, 5, 4, 3, 10, 21, 43, > 90,112,123,128,127,118,107, 85, 39, 17, 6, 1, 2, 11, 22, 44, > 80,103,120,122,121,114, 98, 83, 49, 26, 9, 7, 8, 15, 31, 46, > 72, 96,104,105,106, 97, 93, 75, 57, 33, 25, 24, 23, 32, 36, 54, > 66, 73, 81, 91, 92, 82, 74, 67, 63, 56, 48, 38, 37, 47, 55, 62 }; > >The only reference you need for this stuff is "Digital Halftoning" by >Robert Ulichney, MIT Press, ISBN 0-262-21009-6. >--- I just noticed that the right half of your 8x16 matrix really is a 8x8 halftone matrix. Thankx. I forgot to ask for a 16x16 matrix as well, don't suppose you have one do you? Does anyone know if I can contact the MIT Press directly to order the book? Thankx again! Regards, David B