Method and device of image correction
An Image correction device for detecting an image area having movement according to an image signal, and providing the image signal with image correction and switching correction methods according to a control signal. The image correction device further detects the boundary area of the image area having movement; detects an image area with great gradational change by comparing gradation of image signals corresponding to adjoining pixels; and provides the boundary area of the image area having movement with a diffusion process in an area excluding the image area with great gradational change. The correcting methods performed by the image correcting device can be switched according to the movement signal, thereby improving image correction.
1. An image correction method comprising:
detecting a movement area having a movement according to an image signal by comparing pixels in a frame with pixels in another frame;
detecting a boundary area of the movement area;
detecting a flat area in the frame having a gradational change between adjoining pixels in the frame smaller than a predetermined threshold by comparing gradation of the adjoining pixels in the frame;
determining a first portion of the boundary area located in the flat area;
providing the first portion of the boundary area with a diffusion process, while not providing a second portion of the boundary area with the diffusion process;
correcting a portion of the image signal corresponding to the first portion of the boundary area by a first correction method based on the diffusion process; and
correcting a portion of the image signal corresponding to the second portion of the boundary area by a second correction method different from the first correction method.
2. An image correction device comprising:
movement detecting means for detecting a movement area having movement according to an image signal by comparing pixels in a frame with pixels in another frame;
movement boundary detecting means for detecting a boundary area of the movement area;
gradational change detecting means for detecting a flat area in the frame having a gradational change smaller than a predetermined threshold by comparing gradation of adjoining pixels in the frame;
combination determining means for determining a first portion of the boundary area located in the flat area;
movement signal modulating means for providing the first portion of the boundary area with a diffusion process, while not providing a second portion of the boundary area with the diffusion process; and
image correcting means for correcting a portion of the image signal corresponding to the first portion of the boundary area by a first correction method based on the diffusion process, and correcting a portion of the image signal corresponding to the second portion of the boundary area by a second correction method different from the first correction method.
3. The image correction device of claim 2 , wherein the movement signal modulating means includes a delay circuit that delays an output of the movement detecting means at least in a horizontal direction or in a vertical direction.
4. The image correction device of claim 3 , wherein the movement signal modulating means provides the boundary area of the image area having movement with a diffusion process by randomly switching an amount of delay fed from the delay circuit that delays the output of the movement detecting means in a horizontal direction or in a vertical direction.
5. The image correction method of claim 1 , wherein said determining of the first portion of the boundary area comprises:
calculating the flat area by performing a logical NOT operation on an output from the gradational change detecting means; and
determining the first portion of the boundary area by calculating a logical conjunction of a result from the movement boundary detecting means and the calculated flat area.
6. The image correction device of claim 2 , wherein the combination determining means is operable to:
calculate the flat area by performing a logical NOT operation on an output from the gradational change detecting means, and
determine the first portion of the boundary area by calculating a logical conjunction of a result from the movement boundary detecting means and the calculated flat area.