PDF/Raster is a strict subset of the PDF file format, for storing and transporting multipage raster image documents, especially scanned documents. PDF/raster provides the portability of PDF while offering the core functionality of TIFF. Bitonal, grayscale and truecolor images are supported. Compression options include uncompressed, JPEG, and lossless CCITT Group 4 Fax.
Here we offer a draft of the PDF/Raster Specification
This draft will soon be subject to a ballot in the ISO committee process on the way to becoming an international standard, so please be aware it is possibly subject to change.