Patent ID: 7102697

Claim:
Method for enhancing the contrast of digital images, said digital images comprising a multitude of pixels with each pixel being assigned a luminance level, characterized by the following steps: determining a histogram indicating the luminance level distribution of an original image; determining a characteristic measure (Δ) of the contrast of said original image; equalizing the histogram of the original image in order to improve the contrast, whereby the histogram equalization amount is varied as a function of said characteristic measure (Δ); characterized in that the histogram is equalized by transforming the luminance levels of the original image according to an HE transformation curve, in order to obtain modified luminance levels, said HE transformation curve is generated by integrating and scaling the histogram, and said characteristic measure (Δ) is obtained by evaluating the difference between the mean luminance level of the original image and a predefined constant, whereby a large difference indicates a low-contrast image.