Method of reducing color moire and image processing apparatus using the method
View Patent ↗A method of reducing moire includes generating a moire corrected image by performing moire correction on an input image; setting a moire correction weight for each pixel of the input image based on global luminance of the input image and local luminance of an area including the pixel; and correcting the moire corrected image by synthesizing the input image and the moire corrected image based on the moire correction weight.
1. A method of reducing moire, the method comprising:
generating a moire-corrected image by performing moire correction on an input image;
setting a moire correction weight for each pixel of the input image based on global luminance of the input image and local luminance of an area including the pixel; and
correcting the moire-corrected image by synthesizing the input image and the moire-corrected image based on the moire correction weight,
wherein the setting of the moire correction weight comprises:
calculating a global luminance average value of the input image and a local luminance average value of the area including the pixel;
determining a largest value from among differences between local luminance average values, which are calculated for red, green, and blue, respectively, to be a first maximum difference value; and
setting the moire correction weight of the pixel based on the first maximum difference value.
2. The method of claim 1 , wherein the setting of the moire correction weight comprises:
generating a second maximum difference value by correcting the first maximum difference value; and
setting the moire correction weight of the pixel using the second maximum difference value, and wherein the second maximum difference value is a smaller value between the first maximum difference value and a threshold value.
3. The method of claim 2 , wherein the threshold value is determined by an input received through a user interface.
4. The method of claim 2 , wherein the threshold value is one of the global luminance average value and the local luminance average value.
5. The method of claim 2 , wherein the threshold value is a value obtained by applying a weight to one of the global luminance average value and the local luminance average value.
6. The method of claim 5 , wherein the weight is determined by an input received through a user interface.
7. The method of claim 1 , wherein the area is determined by an input received through a user interface.
8. The method of claim 2 , wherein the moire correction weight is determined based on a ratio of the second maximum difference value to the threshold value.
9. The method of claim 1 , wherein at least one of an upper limit value and a lower limit value is set to at least one of the global luminance average value and the local luminance average value, and
wherein the upper limit value and the lower limit value are determined by an input received through a user interface.
10. An image processing apparatus comprising at least one processor to implement:
a first unit configured to generate a moire-corrected image by performing moire correction on an input image and set a moire correction weight for each pixel of the input image based on global luminance of the input image and local luminance of an area including the pixel; and
a second unit configured to correct the moire-corrected image by synthesizing the input image and the moire-corrected image based on the moire correction weight,
wherein the first unit comprises:
an average calculation unit configured to calculate a global luminance average value of the input image and a local luminance average value of the area including the pixel, and calculate a largest value from among differences between local luminance average values, which are calculated for red, green, and blue, respectively, to be a first maximum difference value; and
a weight setting unit configured to set the moire correction weight of the pixel based on the first maximum difference value.
11. The image processing apparatus of claim 10 , wherein the weight setting unit is further configured to calculate a second maximum difference value by correcting the first maximum difference value and set the moire correction weight of the pixel using the second maximum difference value, and
wherein the second maximum difference value is a smaller value between the first maximum difference value and a threshold value.
12. The image processing apparatus of claim 11 , wherein the threshold value is determined by an input received through a user interface.
13. The image processing apparatus of claim 11 , wherein the threshold value is one of the global luminance average value and the local luminance average value.
14. The image processing apparatus of claim 11 , wherein the threshold value is a value obtained by applying a weight to one of the global luminance average value and the local luminance average value.
15. The image processing apparatus of claim 14 , wherein the weight is determined by an input received through a user interface.
16. The image processing apparatus of claim 10 , wherein the area is determined by an input received through a user interface.
17. The image processing apparatus of claim 11 , wherein the moire correction weight is determined based on a ratio of the second maximum difference value to the threshold value.
18. The image processing apparatus of claim 10 , wherein at least one of an upper limit value and a lower limit value is set to at least one of the global luminance average value and the local luminance average value, and
wherein the upper limit value and the lower limit value are determined by an input received through a user interface.