Question about PDF manipulation

Jules> Looking at the PDF file, I'm not convinced there's any TIFF Jules> data in there to be honest. It looks more like the image is Jules> re-encoded from the input TIFF to PDFs own way of storing Jules> bitmap data - in other words it's not simply a wrapper for a Jules> bunch of TIFF images, but merely a wrapper for bitmap data in Jules> PDF's own format. That's something of a disappointment; I Jules> always thought PDF just encapsulated the input images rather Jules> than re-encoding in any way... Makes sense. The purpose of PDF is to distribute final form documents, for viewing and for printing, including commercial printing. So it's like PostScript, but more rigorously defined, and compressed for space efficiency. A PostScript file produced from an image has the pixels, so they can be printed (in the original colorspace, unless your document manipulation program converted it, as some do or can be told to). Given the purpose of these file formats, there's no reason for it to preserve the TIFF metadata, nor the TIFF format, since the intent is to accurately put pixels on screen or paper. The encoding will be lossless, though (at least normally -- I think you can tell Distiller to use JPG style compression but sensible people know better than that). So when you export the image from the PDF, you get the original pixels back. For purposes of scanned document archives, that is what you need, which is why PDF is fine there. paul