We need it for scanning large numbers of different books, which are never standard sizes, as quickly as possible. Surely such a scanner exists but I cannot seem to find one? Everything seems to be based around standard paper sizes, high res scanning or quick document feeds - none of which we need.
We need a machine that can scan quickly at a low resolution (for the web only) and automatically detect the size of the object being scanned without doing an extra pass. Also the ability to constrain the proportions of images sent to the computer to say 400px wide would be good.