The PDF Association and TWAIN Working Group have announced a partnership to develop a specification called PDF/Raster or PDF/R. It’s described as “a component of TWG’s TWAIN Direct™ initiative, a language/protocol that eliminates the need for users to install vendor specific drivers as communication between scanning devices and image capture software applications.”
I’m not sure what need this is supposed to fill. PDF can be used as an image format, but it’s a rather complicated one. Pamela Doyle, Chair and CEO of the TWAIN Working Group, says:
The TWAIN Direct language is designed to revolutionize how scanners and software communicate. PDF/R, an integral part of this language, provides the portability of PDF while offering the core functionality of TIFF. PDF/R is a strict subset of the ISO-standardized PDF file format for storing and transporting raster image documents, especially scanned documents.
This suggests that TIFF isn’t sufficiently portable but doesn’t explain why. Maybe what concerns them is the entropy which has overtaken TIFF. The current specification (6.0) is dated 1992, and to use it properly today you need to know about three technical notes, a large body of third-party tags, and a certain amount of folk wisdom. On the other hand, the PDF Association tends to make extravagant claims about PDF, calling it an application platform and portraying it in a superhero suit, so a certain amount of bias might be involved.
Other image formats are available, and this attempt to bring PDF into the image format market is an odd one.