Software to clean up photos of whiteboards and documents?

Question

I take a lot of photos of whiteboards, blackboards, and so on for teaching purposes (examples online through May 2010). I'm interested in cleaning them up for archival purposes, preferably using Linux. Commercial products ClearBoard and PhotoNote are priced a little aggressively for my purposes, plus my students would like to have this capability too.

Does anyone know of any good, open source software for

• Converting photographs to images with just a few colors?
• Eliminating perspective distortion?
• Removing unwanted junk from around the edges of an image?

or anything like that? I'm imagining that I start out with a picture of my whiteboard using red and black markers, and I end up with a three-color image using just white, red, and black. Or I photograph a laser-printed document and end up with a clean black-and-white image. I have tried standard tools that reduce the number of colors in an image, and they do a terrible job—probably because they are trying to reproduce the uneven illumination of the original image.

Command-line Linux tools would be ideal.

Answer 1

Here's a blog post describing how to manually clean whiteboard photos in The Gimp.

And here's script that automates a similar process, which can also be invoked from the command line.

I haven't tried either of these myself but they look plausible...

Answer 2

I just created a service a few weeks ago: all you need to do is email your whiteboard picture as an attachment, the service cleans it up and emails it back to you.

The service is called Snapclean.me. The email endpoint is [e-mail]

Yes it's self promotion, it is free, though it doesn't meet all of your criteria at this time, it does brighten / clean up whiteboard pictures.

I hope this helps you get part of the way to where you need to be.

Regards,

Kyle

Answer 3

Some more sites/companies which can clean up whiteboard images:

• Qipit
• Ricoh widget
• scanR

Answer 4

I use JotNot on my iPhone which is pretty amazing (and only cost $1 for full version I think). Simple image capture, with several processing/correction presets and then export to JPG or multi-page PDF.

Wish there was a Windows version though. :-(

Simon.

Answer 5

I use an iPhone app - there are several, such as WhiteBoard Capture Pro

Answer 6

If all you want to do is image enhancement and keystone correction, then the other products mentioned will do variously well.

But if you want that AND the ability to edit the content of the image, such rearranging material to make it more organized, replacing handwriting with typed text in place, editing out junk, and importing other imagery in a collage, you have 2 choices:

1. Full-featured photo editing tools like PhotoShop and Gimp.
2. The experimental program called ScanScribe from Xerox PARC.

Option 1 tools are overkill for things like editing camera images of notes and whiteboards.

Option 2 is unpolished but is an extension of the PowerPoint UI and when you wrap your head around it it is really quite powerful.

Answer 7

When it comes to command-line image processing on Linux, I have to admit ImageMagick is king. It's free and open source, of course :)

It sounds like the main thing you'd like to achieve is sharpening and lessening the amount of colors used in the image.

For example, to convert an image to 256 colors:

convert input.png -colors 256 output.png