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Color constancy in different illumination condition

asked 2013-03-12 14:47:40 -0500

berak gravatar image

updated 2015-09-16 18:08:38 -0500

Hi all. In a paper I'm reading is written: "RGB images taken from the camera are first passed through a pre-processing stage which helps to maintain the colour constancy in different illumination conditions." (focus is road signs recognition in a real time system). Is there a method in OpenCV to do this?

Best regards Costantino

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please accept my apologies, i accidentally deleted your question, instead of my comment ;(

berak gravatar imageberak ( 2013-03-12 14:49:13 -0500 )edit

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answered 2013-03-13 08:49:28 -0500

The standard way of handling this variation is by performing a normalization of the lightning.

  • The easiest way is to use cv::equalizeHist / cvEqualizeHist. This will equilize the contrast over the input images.
  • Gamma correction can be done using cv::pow / cvPow
  • Difference of Gaussian approach can be done with cv::gaussianBlur / cvSmooth to get two different images then use cv::sub / cvSub to get the Difference of Gaussian.

But there are many other ways (including a Contrast Stretch, a Log filter, CLAHE, or even White Color Balancing or Retinex), that can work better or worse depending on your opinion and your project.

Some guidance:

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Thanks for the reply.

Costantino

Costantino gravatar imageCostantino ( 2013-03-13 10:16:43 -0500 )edit
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answered 2013-05-07 04:58:56 -0500

You can check this paper:

Tan, X., and Triggs, B. "Enhanced local texture feature sets for face recognition under difficult lighting conditions.". IEEE Transactions on Image Processing 19 (2010), 1635–650.

Source code is here

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Thanks a lot Costantino

Costantino gravatar imageCostantino ( 2013-05-14 13:04:56 -0500 )edit

Thanks for the source code! Awesome

Entreco gravatar imageEntreco ( 2013-05-15 09:24:15 -0500 )edit
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Asked: 2013-03-12 14:47:40 -0500

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Last updated: Oct 14 '14