| 摘要 |
PROBLEM TO BE SOLVED: To reduce gradation distortion occurred when the color picture of multi-gradation and the like are displayed by correcting video data of a picture element in a correction object area HA through the use of a shift direction and shift quantity. SOLUTION: A correction object detection circuit 10 detects whether an area forms the correction object area HA or not. A gradation distribution detection circuit 12 counts the number of distributions of the respective gradations on the whole picture elements in the correction object area HA based on video data A. A shift direction judgment circuit 14 obtains center data Dc of the gradation distribution, compares center data Dc with boundary data of the specified gradation where gradation distortion occurs and judges the shift direction. A shift quantity calculation circuit 16 calculates a difference between an upper limit value D and a lower limit value E, which are detected by restricting them to be within a setting gradation range KA (upper limit value B and lower limit value C) as shift quantity. An addition/subtraction circuit 18 corrects video data of the respective picture elements in the correction object area HA and set them as output data by using the shift direction and shift quantity.
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