| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image with a high contrast intensification effect in a low-contrast image. SOLUTION: A video signal input unit outputs an input video signal from the outside to a histogram calculation unit and a level conversion unit. The histogram calculation unit calculates a luminance histogram for a luminance level average among a plurality of frames of each of pixels in the image signal and outputs the luminance histogram to a frequency threshold determination unit and a level conversion function calculation unit. The frequency threshold determination unit performs frequency division on the luminance histogram, calculates an average value of signal level differences within divided sections, and calculates differentials (ΔL2-ΔL1,ΔL3-ΔL2, ...) between adjacent sections of these signal level difference average values. If the differential of average values of signal level differences investigated from up to down is a fixed value RTH or smaller continuously for N differentials and a differentialΔLN+1-ΔLN exceeds the fixed value RTH in an (N+1)th frequency divided section, this image is determined as an image having a peak and the frequency at a time when the differential exceeds the fixed value RTH is calculated as a frequency threshold for the peak. COPYRIGHT: (C)2008,JPO&INPIT
|
