Automatic contrast enhancement
First Claim
9. A method of contrast correction comprising providing digital image data, representing the data in the form of a brightness histogram, determining a measure of central tendency for said histogram, and applying to brightness values of the image an S-shaped tone reproduction curve that does not change a measure of central tendency of the brightness histogram.
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Abstract
A method of automatic contrast correction comprises providing digital image data, representing the data in the form of a brightness histogram, determining a measure of central tendency for said histogram, adding a shift value to the measure of central tendency to provide an adjusted measure of central tendency, using the both the determined and adjusted measures of central tendency to determine the exponent of a tone reproduction curve, and applying the tone reproduction curve to the brightness values of the image. Additionally, the method may provide further correction by applying to the brightness values of the image an S-shaped tone reproduction curve that does not change a measure of central tendency of the brightness histogram.
138 Citations
29 Claims
- 9. A method of contrast correction comprising providing digital image data, representing the data in the form of a brightness histogram, determining a measure of central tendency for said histogram, and applying to brightness values of the image an S-shaped tone reproduction curve that does not change a measure of central tendency of the brightness histogram.
- 10. A method of automatic contrast correction comprising providing digital image data, representing the data in the form of a brightness histogram, determining a measure of central tendency for said histogram, and applying to brightness values of the image an S-shaped tone reproduction curve that does not change a measure of central tendency of the brightness histogram, wherein the shape of the S-shaped tone reproduction curve is determined by linear regression on the integral brightness histogram.
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27-1. A computer comprising hardware and software that can execute the method of claim 9 from memory in the computer.
Specification