| 摘要 |
PROBLEM TO BE SOLVED: To correctly eliminate noise by correctly detecting a uniform area. SOLUTION: An analog luminance signal Ya is converted into a digital luminance signal Yd by an A/D converter 10 and supplied to a differentiator 11, a histogram generator 12 and a coefficient memory 15. An absolute value (absolute differentiated value) adv of the second-order differentiated value of the digital luminance signal Yd is calculated by the differentiator 11 and supplied to the histogram generator 12. The histogram generator 12 counts the luminance level of a digital luminance signal Yd (i, j) having the absolute differentiated value smaller than a prescribed threshold value among the absolute differentiated value adv and generates a histogram H at the luminance level for one picture. A histogram smoothing unit 13 smoothes the histogram H and generates a smoothed histogram H'. Based on the smoothed histogram H', a coefficient calculator 14 calculates a uniform area coefficient and supplies a coefficient table C to the coefficient memory 15. The coefficient memory 15 makes the uniform area coefficient correspondent to each picture element position in one picture. |
