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2005.05.26 01:50 "Re: Jpeg and YCbCr", by Kelvin Zhong
> This operations are done by libtiff if you uncomment > TIFFSetField(m_tif, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB); > in the program you have posted. > > Best would be to have a tiffinfo of tiffdump of the file that > acdsee don't want to open. Thanks Jean-Yves, I have already done the things like you said,comment the TIFFSetFiled(m_tif,TIFFTAG_JPEGCOLORMODE,JPEGCOLORMODE_RGB)...,but still doesn't work. I created a JPEG-IN-TIFF file with ACDSEE. (FILE 1) WITH tiffdump,i see follows: Magic: 0x4949 <little-endian> Version: 0x2a Directory 0: offset 12576 (0x3120) next 0 (0) ImageWidth (256) SHORT (3) 1<422> ImageLength (257) SHORT (3) 1<158> BitsPerSample (258) SHORT (3) 3<8 8 8> Compression (259) SHORT (3) 1<7> Photometric (262) SHORT (3) 1<6> StripOffsets (273) LONG (4) 1<8> Orientation (274) SHORT (3) 1<1> SamplesPerPixel (277) SHORT (3) 1<3> StripByteCounts (279) LONG (4) 1<12567> XResolution (282) RATIONAL (5) 1<96> YResolution (283) RATIONAL (5) 1<96> PlanarConfig (284) SHORT (3) 1<1> ResolutionUnit (296) SHORT (3) 1<2> 347 (0x15b) UNDEFINED (7) 574<0xff 0xd8 0xff 0xdb 00 0x43 00 0x8 0x6 0x6 0x7 0x6 0x5 0x8 0x7 0x7 0x7 0x9 0x9 0x8 0xa 0xc 0x14 0xd ...> YCbCrSubsampling (530) SHORT (3) 2<1 1> ReferenceBlackWhite (532) RATIONAL (5) 6<0 255 128 255 128 255> then i use my code to read this pic, and save it with compression = COMPRESSION_JPEG & photometric = PHOTOMETRIC_YCBCR with tiffdump,i saw follows:(FILE 2) Magic: 0x4949 <little-endian> Version: 0x2a Directory 0: offset 19642 (0x4cba) next 0 (0) ImageWidth (256) SHORT (3) 1<422> ImageLength (257) SHORT (3) 1<158> BitsPerSample (258) SHORT (3) 3<8 8 8> Compression (259) SHORT (3) 1<7> Photometric (262) SHORT (3) 1<6> StripOffsets (273) LONG (4) 1<8> Orientation (274) SHORT (3) 1<1> SamplesPerPixel (277) SHORT (3) 1<3> RowsPerStrip (278) SHORT (3) 1<158> StripByteCounts (279) LONG (4) 1<19633> XResolution (282) RATIONAL (5) 1<96.512> YResolution (283) RATIONAL (5) 1<96.512> PlanarConfig (284) SHORT (3) 1<1> ResolutionUnit (296) SHORT (3) 1<2> 347 (0x15b) UNDEFINED (7) 574<0xff 0xd8 0xff 0xdb 00 0x43 00 0x8 0x6 0x6 0x7 0x6 0x5 0x8 0x7 0x7 0x7 0x9 0x9 0x8 0xa 0xc 0x14 0xd ...> YCbCrSubsampling (530) SHORT (3) 2<1 1> ReferenceBlackWhite (532) RATIONAL (5) 6<0 255 128 255 128 255> After doing some comparing things,i found almost every tag is same. except for the StripBytesCounts ,and the file i created has one tag RowsPerStrip which the file ACDSEE created didn't have. but this file(i created) still can't be opened by ACDSEE5. I opened this file(I created,file 2) in LeadTools ,the image color seems changed a lot. so i modify the Photometric tag value from 6 to 2,(PHOTOMETRIC_YCBCR =6,& PHOTOMETRIC_RGB=2),this time the color seemed right.(in Leadtools,ACDSEE can't open it). so I doubt if the libtiff really write the image data as i want to write ? with compression = COMPRESSION_JPEG & photometric = PHOTOMETRIC_YCBCR ? (as i think, even if i set photometric = PHOTOMETRIC_YCBCR ,it still write the image data as photometric = PHOTOMETRIC_RGB,... so when i changed the Photometric tag value from 6 to 2, the color seems right...) related codes & similar questions can be found with title: 2005.5.24:"Question about Jpeg-in-tiff, JPEG IN TIFF created by libtiff can't be read by acdsee", by <yourpattern@126.com> thanks in advance, Kingore@126.com Kelvin Zhong