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February 2006
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2006.02.07 10:26 "Re: Mega newbie question", by Dermot Paikkos
> > I have been reading the docs at awaresystems.com on accessing the > > PhotoShop thumbnails within a tiff file. > > That's .be, man... http://www.awaresystems.be/. Not all that glitters, > is .com. Ouch, should have spotted a Belgium domain. > TIFFGetField(tiff, 33424, &count, &data); > printf("Tag %d: %d, count %d0, 33424, *(uint32 *)data, count); > TIFFGetField(tiff, 36867, &count, &data); > printf("Tag %d: %s, count %d0, 36867, (char *)data, count); Is there a missing " mark here? > I'm not too sure why count is declared uint16 here... It should be > uint32 if you ask me. Plenty of tags have potentially over 64K of data, > and in any case, the count in tags in actual file normal TIFF (not > BigTIFF) is unsigned 32bit. I'm also unsure why datatype is not > returned by this interface... I think it should be if it is to be used > in a robust manner. Otherwise, if the calling code supposes LONG > datatype, but the actual (possibly invalid) file states BYTE datatype, > calling code is next going to boom in an access violation when > accessing past 1/4 of what is supposes is actual data. I can't say I am not entirely sure what is going on with the above code. I looks like it uses stdarg.h to decipher the data-types...but somehow it isn't being complete. Does this mean count is the length of the PS field? ========= test1.c =========== int hasPSfield; unsigned long imageOffset, result; uint16 count; void *data; TIFF* tif = TIFFOpen("test.tif", "r"); if (tif == NULL) { printf("Failed to open file\n"); exit(8); } TIFFGetField(tif,TIFFTAG_PHOTOSHOP &hasPSfield); if (hasPSfield < 1) { printf("No PhotoShop tag found\n"); exit(8); } TIFFGetField(tif, hasPSfield, &count, &data); printf("Tag %d: %d, count %d\n", hasPSfield, *(uint32 *)data, count); /* TIFFGetField(tif, hasPSfield, &count, &data); printf("Tag %d: %s, count %d\n", hasPSfield, (char *)data, count); */ printf("Value of GetField = %d\n", hasPSfield ); TIFFClose(tif); return 0; ============================ returns: TIFFReadDirectory: Warning, test.tif: wrong data type 1 for "XMLPacket"; tag ignored. TIFFReadDirectory: Warning, test.tif: unknown field with tag 34665 (0x8769) encountered. Tag 10124416: 11328828, count 2052 Value of GetField = 10124416 I am still unclear where I should start to loop from (value of m in pseudo-code). > Good luck. Don't be shy to post your results, I would welcome any good > actual code contribution to the Photoshop tag page. Not sure I can produce any 'good code' as yet but I'll always put what I have up for examination. Thanx for the help. Dp.