OE 30. Color Calibration - alalek/opencv GitHub Wiki

Create MacBeth Color Calibration finders and Color Adjustment algorithm

• Author: Gary Bradski
• Link: The feature request
• Status: Draft
• Platforms: All
• Complexity: 1-2 man-months

Introduction and Rationale

Color calibration is extensively used in film and for photometric needs, but OpenCV neglects this basic area. We need to create a couple of functions that will

• Find a MacBeth ColorChecker chart and its homography (robust please to someone holding its corners by hand)
• Return the colors
• Run a color adjustment algorithm on it

Proposed solution

• Create a function that will robustly find common MacBeth charts (allowing for partial occlusion of hands holding the corners) and their homography
  • This one
  • and the standard one
• Rectify the chart and find each color value in order (detecting partial occlusion of say hands holding he corners)
• Apply a color correction algorithm
  • Linear correction matrix
  • More extensive list of linear and polynomial corrections

Impact on existing code, compatibility

Overall, the external API will not change.

Possible alternatives

Many, you could find the chart and correct colors using a trained deepnet. It would be good to create the above functions and then maybe a toolbox app that ran them.

References

• Macbeth chart
  • Linear correction matrix
  • More extensive list of linear and polynomial corrections
  • Vinyl Macbeth Chart
  • Standard Macbeth chart

• Rectify the chart and find each color value in order (detecting partial occlusion of say hands holding he corners)