I recently received 8 pages of scans at 4961x7096, compressed using the greyscale variant of JPEG. While compressed to ~3M each, viewing them on my 256M ram computer was rather interesting. Many of the applications I tried left my HD led on as they tried to uncompress rather more than was good for them. With one page open at a time it was bearable, but when I opened several at a time it got out of control. A secondary issue was that these scans were sent as landscape, when the writing was portrait.
I would suggest that this is an interesting use case for people who use scans casually, and therefore end up with unwieldy image files because it was easier to use a very high resolution than take time to find the most suitable resolution. This is all rather subjective, but I found the best solution was to wrap the JPEGs in PDF (as opposed to the usual JFIF for .jpeg/.jpg files) using sam2p and use evince. <insert praise for evince here>. Acrobat reader on linux was less useable, partly because scrolling was rather jerky <more praise unto evince>. sam2p took a couple of seconds, and left the filesizes virtually the same, so I'm confident the image data was exactly the same. evince appears to have a relatively undocumented feature of opening JFIFs directly, but showed a significant difference in performance (read thrashing). I'm not going to attach 2M image files but this should all be reproducable simply by creating large images. It would probably be easier to see problems with nonblank images, e.g. to test scrolling, and to make sure that some bug in evince isn't causing the page to be drawn as blank anyway (I've experience such a problem in evince only, many times, seemingly triggered by scrolling). My queries are whether it would be possible to a) get evince to display the JFIFs with the same performance as the PDFs by switching backends (if thats the problem) or generalizing smarts in evince (if thats what makes the PDF viewing bearable). b) improve the performance of rotation by performing it as late as possible in the rendering chain, after scaling. I don't know whether there are embedded orientation-sensitive user interface elements e.g. in PDF forms which would obstruct this. I'm afraid I'm unlikely to have the interest to follow this up, apart from documenting it in more detail. If requested I might get as far as writing a test case to create blank images which are large with respect to the RAM available on any given computer. _______________________________________________ Evince-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/evince-list
