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OH... and the RLE encoding can be improved since many (most?) pages of most PDFs (those containing text only and no images) will be black and white only (or may have four or fewer shades used). By including a Bits-Per-Pixel specification at the beginning of each page, followed by a pallet (so any two or four out of the 16 possible shades of grey can map to one and two-bit representations as appropriate), black and white pages will take up significantly less storage at eight pixels per byte instead of two (and thus RLE compressed in packs of eight as well). Preserve 8-bit color depth for pages with photographic images (perhaps identified by the script as pages with over a threshold number of shades in use) so that the device can better interpolate while scaling the full-sized image down to the reader's display before 'rounding' to 4 bits - that *SHOULD* improve the quality of down-sampled photos (though they'll look the same in landscape scrolled view since they won't be resized). I think just making note of which pages are really one-bit should be a huge space-safer, with most text-only documents being packed into eight-pixel per byte, run-length encoded horizontally and vertically, high-quality documents pre-rendered on the computer should take up very little space on the reader.
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