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January 2010
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2010.01.07 19:47 "Re: create simple tiff", by Bob Friesenhahn
On Thu, 7 Jan 2010, Kavallieratou Ergina wrote: > Thank you Bob for the fast answer. I appreciate it. > > You did not say what format the data accessed via imagen->data[] is. > I am sorry it is unsigned char ** data. > > The data needs to be packed the same as TIFF, with each 8-bit byte > representing 8 pixels. > How can I do that, please? could you give me a sign? I can not write your code for you, but you are free to look at GraphicsMagick for some examples. One generic approach is my "bit stream" interface which supports marshalling an arbitrary (1-32) bits in big-endian order: http://cvs.graphicsmagick.org/cgi-bin/cvsweb.cgi/GraphicsMagick/magick/bit_stream.h?rev=1.12.4.1;content-type=text%2Fx-cvsweb-markup http://cvs.graphicsmagick.org/cgi-bin/cvsweb.cgi/GraphicsMagick/magick/bit_stream.c?rev=1.1.2.1;content-type=text%2Fx-cvsweb-markup More specific and efficient algorithms may be found in the ExportViewPixelArea() function in this source module: http://cvs.graphicsmagick.org/cgi-bin/cvsweb.cgi/GraphicsMagick/magick/constitute.c?rev=1.389;content-type=text%2Fx-cvsweb-markup Look at the 'GrayQuantum' case. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/