Thursday, 30 December 2010

Postprocessing scanned crayon images

Postprocessing crayon drawings

I have some scans of crayon drawings, but the colours are washed out (well, the colours are pretty light on paper too):


First, some due dilligence. Google for solutions. (Actually, first fire up GIMP and try a few ideas. But let's pretend I hit the books before hitting the lab).

Lit review:

  1. google'd: post processing scanned crayon drawings - no help, but kids drawing reenacted was entertaining.

  2. google'd: scanning crayon drawings - better, results in a yahoo answers entry... which suggests GIMP. Also a couple of references warning about crayon wax sticking to scanners (I didn't have this problem).

  3. searched flickr for examples in the hope of finding a discussion in comments. Photos tagged with crayon art was the best of the flickr searches. Several people, including Steve brandon, used a camera, rather than a scanner.


Ok, that's enough searching. Let's play with some balances. Here's screenshots of the settings (from GIMP's colour menu) and the changed versions of the image.

original


take 1






take 2





I bumped up blue similarly.


take 3





Applied these settings after inverting the image.


take 4






take 5





I expanded this settings box out to make fine control easier.



In the end I went with the first take, as the least abstract of the bunch.


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