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Thread Subject:
Color correct / normalize image using color checker

Subject: Color correct / normalize image using color checker

From: Tim Brown

Date: 14 Jun, 2013 09:35:09

Message: 1 of 1

Hi all,

We have a time-series of images of plants growing. Our growth chambers have dynamic lighting conditions so the lighting changes a lot during the course of the day. We need to compare green pixel values, etc between images but before we can do that the color needs to be adjusted to account for lighting variations All the images have a x-rite (equivalent) color checkers in them and I'm trying to figure out how to color correct the images. I've seen a number of posts on more generic color correction and normalization but I'm still not clear on how I can color and brightness shift using the values from the color checker so that images taken under different lighting conditions are somewhat comparable. Any code examples or suggested reading on the theory behind how to do color correction using a color checker would be appreciated.

Here's a move showing how the lighting changes over the day:
http://www.youtube.com/watch?v=wMt5xtp9sH8&HD=1

Sample images:
Morning: http://phenocam.anu.edu.au/data/timestreams/Borevitz/sampleimages/morning.JPG
Noon: http://phenocam.anu.edu.au/data/timestreams/Borevitz/sampleimages/noon.JPG

Thanks!

Tim

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