METHOD FOR ENHANCING DIGITAL IMAGE WHILE RESTRAINING UNDERSHOOT AND OVERSHOOT

摘要

PURPOSE: A method for enhancing a digital image while restraining undershoot and overshoot is provided to enhance details of the digital image while restraining undershoot and overshoot generated during an enhancement process. CONSTITUTION: A first image signal including pixel values is obtained. A high band pass image signal having high frequency components of the first image signal is obtained. A positive weighted factor, not zero, controlling degree of enhancement is obtained. Edge pixel values expressing a boundary of an edge of a first image are selected. A gain restrain function is defined. The gain restrain function has attenuation coefficients multiplied by peculiar pixel values of a high band image signal at a position corresponding to the edge pixels for restraining shoots. The high band pass image signal is multiplied by the weighted factor and the gain restrain function. The first image signal is multiplied by the result of the multiplication to obtain an enhanced image signal restraining the shoots.