| 摘要 |
PURPOSE:To eliminate the picture noise while keeping a picture in high contrast by detecting the edge part of a picture to display the area near the edge in a high contrast with no averaging and performing the averaging at the area excepting the edge part to have a display in the form of smooth signals. CONSTITUTION:A separated luminance signal is supplied to an averaging circuit 4, and the original signal (x) is subtracted from the averaged signal (x') by a subtractor 5. This (x-x') shows a local variance factor of a picture, and the signal (x-x') is supplied to a deciding ROM6. Then the signal (x-x') is multiplied by the contents (k) of the ROM6 by a multiplier 7 and then added with the signal (x') by an adder 8. Thus the output (y) is equal to x'+k(x-x'), and y=x' is satisfied if the (k) is set at 0. Thus an averaged waveform is obtained. Then y=x is satisfied when the (k) is set at 1 to obtain a original sharp signal. Thus it is possible to control the averaging degree according to the local variance factor of a picture by changing the value of (k) in response to the ROM address. |
