Patent Document ID: 8180172
Application ID: 11824033
Patent Status: 1

Claim One:
1. An image processing method for correcting an original image, the method comprising: performing a retinex processing on a luminance signal of each pixel in an original image that is indicative of a luminance component of an original color of each pixel, the retinex processing comprising: calculating a peripheral average luminance for each pixel in the original image; calculating a reference value that is a logarithm of a first value that is obtained by dividing the luminance signal by the peripheral average luminance; normalizing the reference value; setting a parameter γ 1 as a constant greater than zero (0); calculating a second value obtained by dividing the luminance signal by the normalized reference value; and calculating a corrected luminance signal by dividing the luminance signal by the second value raised to a (1−1/γ 1 )-th power; determining, for each pixel, a retinex-processed pixel value based on the luminance signal that has been subjected to the retinex processing and at least one signal other than the luminance signal that is indicative of a component other than the luminance component of the original color of the each pixel; obtaining, for each pixel value, the luminance signal and the at least one other signal based on an original pixel value indicative of the original color of the each pixel; generating a histogram by counting a rate of occurrence of the retinex-processed pixel values for each level over a predetermined first range of pixel values having a maximum value and a minimum value to which the retinex-processed pixel value is possibly assigned; and reassigning each pixel value based on the histogram, the reassigning step comprising: setting a lower end value and an upper end value in the first range; setting a lower range between the minimum value and the lower end value and an upper range between the upper end value and the maximum value; setting a second range by removing the upper range and the lower range, from the first range; and transforming a retinex-processed pixel value that falls in the second range to a pixel value falling in the first range.