Apparatus and method for enhancing images in consideration of region characteristics

1. An apparatus for enhancing images in consideration of region characteristics, comprising:

an inverse gamma correction unit for releasing gamma correction and linearizing each of Red (R), Green (G), and Blue (B) colors;

a threshold calculation unit for calculating m-1 thresholds in order to divide brightness of pixels into m regions, and labeling each of the pixels as one of the m brightness regions;

a block segmentation unit for dividing an input image into M×N blocks;

a block statistics calculation unit for determining one of the m brightness regions to which each of the blocks pertains, and labeling the blocks as a corresponding brightness region;

a block-based Look-Up Table (LUT) generation unit for generating enhancement LUTs for the respective blocks;

an image enhancement unit for enhancing the image using the LUTs for the respective blocks, which are generated through the block-based LUT generation unit; and

a gamma correction unit for performing gamma correction and wherein the block-based LUT generation unit generates LUTs for the respective blocks by combining m LUTs, primary LUTs for the respective blocks being generated by combining the LUTs of the respective blocks using overlapping of brightness regions and block indexes for m basis LUTs, and final LUTs for the respective blocks being generated using averages or weighted averages between the primary LUTs for respective blocks and LUTs for adjacent blocks.

2. The apparatus as set forth in claim 1 , wherein the inverse gamma correction unit performs inverse gamma correction using a number of bits greater than a number of bits of the input image, in order to prevent values having different levels before the gamma correction from being changed into values having an identical value after the gamma correction.

3. The apparatus as set forth in claim 1 , wherein the threshold calculation unit calculates the brightness region thresholds, performs division into a plurality of brightness regions, and varies enhancement strength depending on a corresponding region.

4. The apparatus as set forth in claim 1 , wherein the block segmentation unit overlaps the respective blocks in order to remove differently processed portions of edges between the blocks.

5. The apparatus as set forth in claim 1 , wherein the block statistics calculation unit calculates block indexes including an index of a region having a largest distribution in each of the blocks, a center of gravity of a block, ratios of each of m brightness regions in the block, and a brightness average and brightness dispersion of the block.

6. The apparatus as set forth in claim 1 , wherein the block-based LUT generation unit generates a number of basis LUTs equal to the number of brightness regions.

7. The apparatus as set forth in claim 1 , wherein the image enhancement unit corrects values of the pixels in each of the blocks using the LUTs for respective blocks generated through the block-based LUT generation unit, an average or weighted average of enhancement result values based not only on the LUT for a relevant block in which the pixel is included but also on LUTs for adjacent blocks being obtained as a final enhancement result value.

8. A method of enhancing images in consideration of region characteristics, comprising the steps of:

(a) an inverse gamma correction unit releasing gamma correction applied for display of an image, and linearizing each of R, G, and B colors;

(b) a threshold calculation unit calculating m-1 thresholds in order to divide brightness of pixels into m regions, and labeling each of the pixels as one of the m brightness regions;

(c) a block segmentation unit dividing an input image into M×N blocks;

(d) a block statistics calculation unit calculating block indexes capable of indicating statistical characteristics of the blocks, determining one of the m brightness regions to which each of the blocks pertains, and labeling the blocks as a corresponding brightness region;

(e) a block-based Look-Up Table (LUT) generation unit generating primary LUTs for the respective blocks by combining LUTs for the respective blocks using overlapping of brightness regions and block indexes for m basis LUTs, and then generating final LUTs for the respective blocks by obtaining averages or weighted averages between the primary LUTs for the respective blocks and LUTs for adjacent blocks;

(f) an image enhancement unit enhancing values of the pixels of the blocks using the LUTs for the respective blocks generated through the step (e); and

(g) a gamma correction unit applying again gamma correction that has been released through the inverse gamma correction unit.

9. The method as set forth in claim 8 , wherein the step (a) comprises the inverse gamma correction unit performing inverse gamma correction using a number of bits greater than a number of bits of the input image.

10. The method as set forth in claim 8 , wherein the step (b) comprises the threshold calculation unit calculating the brightness region thresholds, performing division into a plurality of brightness regions, and varying enhancement strength depending on a corresponding region.

11. The method as set forth in claim 8 , wherein the step (c) comprises the block segmentation unit overlapping the respective blocks in order to remove differently processed portions of edges between the blocks.

12. The method as set forth in claim 8 , wherein the step (d) comprises the block statistics calculation unit calculating block indexes including an index of a region having a largest distribution in each of the blocks, a center of gravity of a block, ratios of each of m brightness regions in the block, and a brightness average and brightness dispersion of the block.

13. The method as set forth in claim 8 , wherein the step (e) comprises the block-based LUT generation unit generating a number of basis LUTs equal to the number of brightness regions.

14. The method as set forth in claim 8 , wherein the step (e) comprises the block-based LUT generation unit generating LUTs for the respective blocks by combining m LUTs, primary LUTs for the respective blocks being generated by combining the LUTs of the respective blocks using overlapping of brightness regions and block indexes for m basis LUTs, and final LUTs for the respective blocks being generated using averages or weighted averages between the primary LUTs for respective blocks and LUTs for adjacent blocks.

15. The method as set forth in claim 8 , wherein the step (f) comprises the image enhancement unit enhancing values of the pixels in each of the blocks using the LUTs for respective blocks generated through the block-based LUT generation unit, an average or weighted average of enhancement result values based not only on the LUT for a relevant block in which the pixel is included but also on LUTs for adjacent blocks being obtained as a final enhancement result value.