Camscanner allows your Android or iOS smartphone to function as a document scanner. And while there are other competing apps from the few I’ve tried it’s clear that Camscanner is the pack leader.
This app is better than the rest because it is intuitive and produces great results. It includes a virtual bubble-level shown on the screen when you are taking the photo, so you get the picture straight on and undistorted. When you get it level, it disappears, which is excellent design (both giving feedback that you ‘got it right’ and uncluttering the view at the same time). [Note: Strangely, the bubble level seems to be an Android-only feature.--OH]
When you need to crop, the cropping screen shows a thumbnail ‘peek’ window at the opposite corner while you pull the crop line, showing crosshairs of where you are placing the corner on the photo. No need to try multiple times since you can’t see what is happening under your thick finger! The layout is very intuitive, five unambiguous icon buttons, and a quickstart document with a guided tour included (no searching for the documentation)! Did I say great design?
After you’ve scanned something the cropping and enhancing happen before your eyes, recapturing some of the thrill of watching a Polaroid develop. The enhancement options work well, turning even faint pencil scratchings into well contrasted digital versions.
Once the document has been processed, Camscanner can either email or upload the document as a JPG or PDF to a number of hosting services including Google Docs, Dropbox, Box.net, Evernote, and iDisk.
There are no ads in the free version, though it is limited to generating 10-page scan-pdf’s with a ‘watermark’ line at the bottom of each page and also doesn’t feature the Optical Character Recognition (OCR) for text searches or AirPrint (which is iOS only). But other than that no annoying (and bandwidth guzzling, cpu-battery hogging) ads! The full version costs $5 and removes all limitations.
[I gave the free version of Camscanner a run through on my iPhone 4 and it really is far better than any other scanning apps I've tried. Its flexible processing engine turns out very readable PDFs (here is a link to a sample PDF I made) even in crappy light. It should be noted, though, that this application is limited by the quality of the phone's camera.--OH]