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> > I have a PDF file that contains a TIFF image.
>
> PDF files do NOT contain TIFF images.   They may contain image data
> that at one time in the past was a TIFF - but by the time it is
> processed into a PDF, it is no longer valid TIFF data.  Hence, libtiff
> fails.

Indeed. What you have saved to the file is probably the raw LZW-
compressed image data. What you can do is construct a TIFF *around*
that, if you also read the size, colour space, etc. from the PDF.

For the most common ways to encode and compress images, there is a
remarkable correspondence between the way TIFF and PDF encode them,
so lossless conversion is often possible. But it isn't true that you
can simply embed a TIFF in a PDF, nor the reverse.

					Gerben Vos.


AWARE [SYSTEMS]		Imaging expertise for the Delphi developer
		TIFF and LibTiff Mailing List Archive
	LibTiff Mailing List TIFF and LibTiff Mailing List Archive March 2006 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 2006.03.28 20:29 "extracting TIFF image from PDF and decompressing with Libtiff", by Philip Watkinson 2006.03.28 20:50 "Re: extracting TIFF image from PDF and decompressing with Libtiff", by Bob Friesenhahn 2006.03.28 22:28 "Re: extracting TIFF image from PDF and decompressing with Libtiff", by Leonard Rosenthol 2006.03.29 16:33 "Re: extracting TIFF image from PDF and decompressingwith Libtiff", by Gerben Vos 2006.03.29 16:33 "Re: extracting TIFF image from PDF and decompressingwith Libtiff", by Gerben Vos > > I have a PDF file that contains a TIFF image. > > PDF files do NOT contain TIFF images. They may contain image data > that at one time in the past was a TIFF - but by the time it is > processed into a PDF, it is no longer valid TIFF data. Hence, libtiff > fails. Indeed. What you have saved to the file is probably the raw LZW- compressed image data. What you can do is construct a TIFF around that, if you also read the size, colour space, etc. from the PDF. For the most common ways to encode and compress images, there is a remarkable correspondence between the way TIFF and PDF encode them, so lossless conversion is often possible. But it isn't true that you can simply embed a TIFF in a PDF, nor the reverse. Gerben Vos.

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2006.03.29 16:33 "Re: extracting TIFF image from PDF and decompressingwith Libtiff", by Gerben Vos