Patent ID: 8406559

Claim:
A method for enhancing image sharpness based on local features of image, which performs a sharpness enhancement operation on an image formed of pixels, each of the pixels having a luma value, arranged in a matrix form, the method comprising the steps of: (A) extracting local features from a local area in the image for finding a maximum luma value and a minimum luma value in the local area to accordingly calculate a difference value between the maximum luma value and the minimum luma value, in which the difference value is obtained by subtracting the minimum luma value from the maximum luma value, and the local area is a 3×3 area centering on the pixel, which includes the pixel and upper left pixel, upper pixel, upper right pixel, left pixel, right pixel, lower left pixel, lower pixel, and lower right pixel of the pixel; (B) calculating a sharpness factor for the pixel according to the difference value; (C) performing a sharpness processing on the pixel according to the sharpness factor; and (D) repeating steps (A), (B), and (C) until the sharpness processing is performed on the pixels of the image completely; wherein the sharpness processing is performed with following equation: p ′=localmean+ s ×(p−localmean), where localmean indicates a local mean value which is obtained by summing luma values of the pixels from the local area to have a summation and then dividing the summation by a number of pixels in the local area, s indicates the sharpness factor, p indicates luma value of the pixel (i, j) before the sharpness processing, and p′ indicates luma value of the pixel (i, j) after the sharpness processing.