Color calibration across multiple images

Question

Hi everyone,
I took a bunch for photos for a scientific documentation project outside in the shade throughout the day, resulting in significantly different lighting. Here are the first and last photos of the day:
http://imageshack.com/a/img841/4403/94vy.jpg (late morning)
http://imageshack.com/a/img208/7861/ibvz.jpg (late afternoon)
The challenge is to use the color strip to calibrate the images so that the colors are consistent in all of them. Note that the color strip was printed without any special attention to calibration, so the absolute values of the colors are not necessarily trustworthy. Also, for these purposes, the paper can be assumed to be pure white. Basically, the idea is to get the absolute calibration as accurate as possible, but really nail the relative calibration, so that the color strip and paper appear essentially identical in all the images. I've tried adjusting levels by sampling known white, grey, and black in the images, but that hasn't done the trick -- clearly a more sophisticated approach is required! That said, I have over 100 of these images to process, so a relatively straightforward solution would be appreciated, if possible.
Please let me know if you can help, and thanks in advance!     

Answer 1

Move on to video editing apps. Seriously. Automatic shot matching features e.g. in Speedgrade or even Premiere's/ After Effects' Auto-Levels can already get you halfway there by doing a temporal comparison within the sequence, not to speak of sophisticated plug-ins like RevisionFX' RE:Match. They may in fact skew the colors oddly or make them appear dull and "too averaged", but that would be quite uniform across the sequence and then much easier to tackle with a global correction.
Mylenium