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TIFF and LibTiff Mail List Archive

Thread

1994.12.23 14:50 "retreiving GrayResponseCurve and undefined tag info", by Bob Kozdemba
1994.12.23 15:02 "Re: retreiving GrayResponseCurve and undefined tag info", by Niles Ritter
1994.12.24 12:48 "Re: retreiving GrayResponseCurve and undefined tag info", by Bob Kozdemba
1994.12.23 16:11 "Re: retreiving GrayResponseCurve and undefined tag info", by Sam Leffler

1994.12.23 16:11 "Re: retreiving GrayResponseCurve and undefined tag info", by Sam Leffler

Is it possible to retreive the GrayResponseCurve array using libtiff? I get zeroes returned. Here are the code fragments. Any ideas?

The short answer is no. GrayResponseCurve is a deprecated tag; the write should be using the Colorimetry tags defined in the TIFF 6.0 spec. The library reads the tag and discards it to avoid generating a warning about an unknown tag. You can easily add support back into your copy of the library.

short grayResponseCurve[256];

TIFFGetField(tif, TIFFTAG_GRAYRESPONSECURVE, grayResponseCurve);

I also need to retreive 32 bytes of info at TAG 65535, which is undefined. I noticed that 'tiffdump' works, but it looks like 'tiffdump' does not use TIFFGetField().

The library only understands a compiled-in set of tags. If you want the value of this tag you'll need to add it in. Some day I'll get around to rewriting the directory handling to keep unknown tags around.

    Sam