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May 2005
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2005.05.26 08:58 "Re: Jpeg and YCbCr", by Kelvin Zhong
Related topics: [Tiff] 2005.5.24:Question about Jpeg-in-tiff, JPEG IN TIFF created by libtiff can't be read by acdsee Hi all, This time i scrathed some codes from rgb2ycbcr.c which is distributed with libtiff/tools.It works, and i successfully created the tif image file with compression = COMPRESSION_JPEG & photometric = PHOTOMETRIC_YCBCR , and can be opened by ACDSEE. thanks all for your help. But i still have some thoughts about this things: Jean Yves: you said that libtiff already can do this thing(save the tif image file with compression = COMPRESSION_JPEG & photometric = PHOTOMETRIC_YCBCR ), I tried,but failed. Do you have done such things before ? if so,tell me what's wrong in my codes,or tell me how to do ? thanks . [ and i looked at manual page of TIFFWriteScanLine()...,it is said,there is a bug related to this: "Writing subsampled YCbCR data does not work correctly because, for PlanarConfiguration=2 the size of a scanline is not calculated on a per-sample basis, and for PlanarConfiguration=1 the library does not pack the block-interleaved samples." so i shift to use TIFFWriteEncodedStrip....,(there is no bug reports in manual page about this function),but it still can't work.). I am so new to compress and de-compress algorithm,so i unable to fix it.... Joris, your idea about how to "attach" & "detach" jpeg-data(already compressed) inspired me a lot, i'd like to try someday after i do some research on the JPEG stream format .. Related knowledge: (It seems ACDSEE can't open the JPEG-IN-TIFF file with photometric = PHOTOMETRIC_RGB) thanks all Kingore@126.com Kelvin Zhong