Nice idea. It would be fantastic if this could be done on the phone during the image capture
There's a whole heap of iOS 'scanning' apps that do this sort of thing device-side.
Or Android.
Show HN: Digitizing photos of whiteboards using the command line
31–37 of 37 posts
Re: Show HN: Digitizing photos of whiteboards using the command line
#32Heh, I remember this from when you posted it on reddit months ago [1]. Glad to see you're the same person and you didn't just take it from them. Very nice script, I've used it before with great success.
[1] http://www.reddit.com/r/commandline/comments/1weqnn/cli_onel...
Re: Show HN: Digitizing photos of whiteboards using the command line
#33Re: Show HN: Digitizing photos of whiteboards using the command line
#34Nice idea, would it be possible to do some OCR at the end?
I did experiment with using this to bring out the text in photos of books. Here's an example: Input image - http://i.imgur.com/6o5FwxG.jpg Output image - http://i.imgur.com/7OIOxfO.png I tried to use vanilla Tesseract on it, but I had no luck getting anything usable out of it.
You have to compensate for the 3D deformation present in the captured image. There has been some impressive work in this area recently.
Some commercial OCR engines such as Nuance Capture SDK have built in functionality for this.
Re: Show HN: Digitizing photos of whiteboards using the command line
#35Cool! I did something similar just recently for cleaning up scans of my laboratory notes (in a moleskin). I have an Automator action which watches the scan folder, automatically crops/splits the pages and cleans them up, then uploads them into Evernote. Gives me a searchable cloud backup of my lab notes! Anyway, I cheated by using some of these actions: http://www.fmwconcepts.com/imagemagick/ In particular the "textc…
Take a look at unpaper instead. It was designed for postprocessing scanned documents. The only thing it does not do is the Evernote upload:
Re: Show HN: Digitizing photos of whiteboards using the command line
#36For those of you who would like to use this on smaller images, play around with "DoG:15,100,0". This string refers to implementing a difference of gaussian filter with inner radius of 15 and outer radius of 100 pixels. This is obviously tied to image size. The first number should always be smaller than the second, and my guess is that it should be on the order of the average width of the text. Just a estimation, I don't have the time to test it right now.
Re: Show HN: Digitizing photos of whiteboards using the command line
#37I'd like to see similar script for blackboards (greenboards?).
If you have black-on-white then try adding -negate after the source image, it'll turn it to black-on-white.
Another approach I took recently was to combine this with -threshold (90 worked well in my case) and the Dilate morphology - I had a black and white set of plans printed using varying-sized dots.