Image processing method and image processor performing the same
In an image processing method that converts image data into output data by performing tone mapping, an edge of an image represented by the image data is determined, a first tone mapping operation is performed on first image data included in the image data, where the first image data represent a first portion of the image not including the edge, whether a gray level of second image data is within a predetermined gray range is determined, where the second image data represent a second portion of the image including the edge, a second tone mapping operation is performed on the second image data when the gray level of the second image data is within the gray range, and the first tone mapping operation is performed on the second image data when the gray level of the second image data is not within the gray range.
1. An image processing method which converts image data into output data by performing tone mapping, the image processing method comprising:
determining an edge of an image represented by the image data;
performing a first tone mapping operation on first image data included in the image data, the first image data representing a first portion of the image not including the edge;
determining whether a gray level of second image data included in the image data is within a predetermined gray range, the second image data representing a second portion of the image including the edge;
performing a second tone mapping operation on the second image data when the gray level of the second image data is within the predetermined gray range; and
performing the first tone mapping operation on the second image data when the gray level of the second image data is not within the predetermined gray range.
2. The image processing method of claim 1 , wherein the first tone mapping operation converts the image data into the output data using a first conversion function, and
wherein the second tone mapping operation converts the image data into the output data using a second conversion function different from the first conversion function.
3. The image processing method of claim 2 , wherein the predetermined gray range includes at least one of a first gray range less than a first threshold gray level and a second gray range greater than a second threshold gray level, and
wherein the second threshold gray level is greater than the first threshold gray level.
4. The image processing method of claim 3 , wherein, in the first gray range, the output data generated by the first tone mapping operation are less than or equal to the output data generated by the second tone mapping operation.
5. The image processing method of claim 3 , wherein, in the second gray range, the output data generated by the first tone mapping operation are greater than or equal to the output data generated by the second tone mapping operation.
6. The image processing method of claim 3 , wherein at least one of the first gray range and the second gray range is adjusted based on an average gray level of the image data.
7. The image processing method of claim 2 , wherein a first absolute difference between the image data and the output data generated by the first tone mapping operation is greater than or equal to a second absolute difference between the image data and the output data generated by the second tone mapping operation.
8. The image processing method of claim 1 , wherein the determining the edge of the image includes:
converting a data format of the image data from an RGB format to a conversion image format where luminance data and chrominance data are separated; and
determining the edge by applying a high-pass filter to the luminance data.
9. The image processing method of claim 1 , further comprising:
obtaining a number of pixels included in the edge; and
performing a bypass operation on an entirety of the image data when the number of pixels is greater than a first threshold value.
10. The image processing method of claim 9 , wherein the output data generated by the bypass operation increase in linear proportion to an increase of a gray level of the image data.
11. The image processing method of claim 1 , wherein the second tone mapping operation converts the image data corresponding to a first color into the output data by a second conversion function to which a first weight is applied, and converts the image data corresponding to a second color different from the first color into the output data by the second conversion function to which a second weight different from the first weight is applied.
12. An image processor which converts image data into output data by performing tone mapping, the image processor comprising:
a signal receiver which receives image contents including the image data and meta data for the image data;
a tone mapper which determines an edge of an image represented by the image data, performs a first tone mapping operation on first image data included in the image data, where the first image data represent a first portion of the image not including the edge, determines whether a gray level of second image data included in the image data is within a predetermined gray range, where the second image data represent a second portion of the image including the edge, performs a second tone mapping operation on the second image data when the gray level of the second image data is within the predetermined gray range, and performs the first tone mapping operation on the second image data when the gray level of the second image data is not within the predetermined gray range; and
an image controller which performs a post-processing operation on the image based on the output data and the meta data.
13. The image processor of claim 12 , wherein the first tone mapping operation converts the image data into the output data using a first conversion function, and
wherein the second tone mapping operation converts the image data into the output data using a second conversion function different from the first conversion function.
14. The image processor of claim 13 , wherein the predetermined gray range includes at least one of a first gray range less than a first threshold gray level and a second gray range greater than a second threshold gray level, and
wherein the second threshold gray level is greater than the first threshold gray level.
15. The image processor of claim 14 , wherein, in the first gray range, the output data generated by the first tone mapping operation are less than or equal to the output data generated by the second tone mapping operation.
16. The image processor of claim 14 , wherein, in the second gray range, the output data generated by the first tone mapping operation are greater than or equal to the output data generated by the second tone mapping operation.
17. The image processor of claim 12 , wherein the tone mapper obtains a number of pixels included in the edge, and performs a bypass operation on an entirety of the image data when the number of pixels is greater than a first threshold value.
18. The image processor of claim 12 , wherein the second tone mapping operation converts the image data corresponding to a first color into the output data by a second conversion function to which a first weight is applied, and converts the image data corresponding to a second color different from the first color into the output data by the second conversion function to which a second weight different from the first weight is applied.