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> You could try to locate the offset to the second IFD, and simply write 
> zero to that. That's 'commenting out', for sure, but I don't know if it's 
> going to help. http://www.awaresystems.be/imaging/tiff/faq.html#q3 
> should probably contain all the information you need to build that.

Hello Joris!  Thanks for your guidance, it worked!

First I had to do my own copy that copied just under 4GB of the file
to a new file, then I found the first IFD, and overwrite the offset
to the next IFD with a zero.

tiffcp still tells me "Seek error accessing tiff directory"
but my own code that reads the file with libtiff can view it!

I wrote the program to do the zeroing in python, and I don't want
to include the destructive lines of code, but here's how I read the
tags:

    f = open(filename,  "r+b")

    # struct:  h is a signed 16 bit integer, 
    # and L is an unsigned 32 bit integer
    (order, version, offset) = struct.unpack('hhL', f.read(8))
    print "header: order", hex(order), "version", version, "offset",
hex(offset), offset

    f.seek(offset)
    (numtags,) = struct.unpack('h', f.read(2))
    print "numtags", numtags
    bytesToSkip = numtags * 12
    f.seek(bytesToSkip, 1)
    (nextIfd,) = struct.unpack('L', f.read(4))
    print "next ifd offset:", hex(nextIfd),  nextIfd

the final step was to seek backward four bytes, then 
write four bytes of 0.

Thanks,
-Jim


AWARE [SYSTEMS]		Imaging expertise for the Delphi developer
		TIFF and LibTiff Mailing List Archive
	LibTiff Mailing List TIFF and LibTiff Mailing List Archive July 2005 Previous Thread Next Thread Previous by Thread Next by Thread Previous by Date Next by Date Contact The TIFF Mailing List Homepage This list is run by Frank Warmerdam Archive maintained by AWare Systems	Thread 2005.07.21 15:33 "Help, I need to do some binary surgery on my tiff.", by James Carroll 2005.07.21 15:58 "Re: Help, I need to do some binary surgery on my tiff.", by Joris Van Damme 2005.07.21 18:28 "Re: Help, I need to do some binary surgery on my tiff.", by James Carroll 2005.07.21 18:28 "Re: Help, I need to do some binary surgery on my tiff.", by James Carroll > You could try to locate the offset to the second IFD, and simply write > zero to that. That's 'commenting out', for sure, but I don't know if it's > going to help. http://www.awaresystems.be/imaging/tiff/faq.html#q3 > should probably contain all the information you need to build that. Hello Joris! Thanks for your guidance, it worked! First I had to do my own copy that copied just under 4GB of the file to a new file, then I found the first IFD, and overwrite the offset to the next IFD with a zero. tiffcp still tells me "Seek error accessing tiff directory" but my own code that reads the file with libtiff can view it! I wrote the program to do the zeroing in python, and I don't want to include the destructive lines of code, but here's how I read the tags: f = open(filename, "r+b") # struct: h is a signed 16 bit integer, # and L is an unsigned 32 bit integer (order, version, offset) = struct.unpack('hhL', f.read(8)) print "header: order", hex(order), "version", version, "offset", hex(offset), offset f.seek(offset) (numtags,) = struct.unpack('h', f.read(2)) print "numtags", numtags bytesToSkip = numtags * 12 f.seek(bytesToSkip, 1) (nextIfd,) = struct.unpack('L', f.read(4)) print "next ifd offset:", hex(nextIfd), nextIfd the final step was to seek backward four bytes, then write four bytes of 0. Thanks, -Jim

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2005.07.21 18:28 "Re: Help, I need to do some binary surgery on my tiff.", by James Carroll