Granted Patent B2

US 9,280,808 · App. 14/453,032 · Granted Mar 8, 2016

Abstract

Claims (41)

1. An apparatus for processing an image, the apparatus comprising:

a transmission estimation unit configured to calculate a transmission of an input image by synthesizing pixel-based transmissions of current pixels of the current image including a fog component, and block-based transmissions of a plurality of blocks of a previous image, each block comprising a plurality of pixels;

an airlight estimation unit configured to calculate airlight of the input image; and

an image restoration unit configured to generate, based on the transmission and the airlight, a restored image in which the fog component is removed from the current image.

2. The apparatus of claim 1 , wherein the transmission estimation unit comprises:

a first transmission estimation unit configured to calculate the pixel-based transmissions by applying a dark channel prior to the current pixels of the current image; and

a second transmission estimation unit configured to calculate the block-based transmissions by applying the dark channel prior to the each block of the previous image, and

wherein the airlight is calculated from a brightest pixel value of a brightest block among the plurality of blocks.

3. The apparatus of claim 2 , wherein the second transmission estimation unit is configured to calculate the block-based transmissions by using a lowest pixel value among the plurality of pixels in the each block of the previous image.

4. The apparatus of claim 3 , wherein the second transmission estimation unit comprises:

a block division unit configured to divide the previous image into the plurality of blocks;

a representative pixel value extracting unit configured to extract the lowest pixel value as a representative pixel value of the each block, by comparing pixel values of the plurality of pixels in the each block; and

a transmission calculation unit configured to calculate the block-based transmissions by using the representative pixel value.

5. The apparatus of claim 4 , wherein the first transmission estimation unit and the second transmission estimation unit are configured to calculate the pixel-based transmission and the block-based transmissions by applying the airlight of the input image.

6. The apparatus of claim 4 , further comprising an interpolation unit configured to interpolate a transmission of the each block and transmissions of neighboring blocks according to a distance between a center of the each block and the current pixels.

7. The apparatus of claim 1 , further comprising a synthesizing unit is configured to synthesize the pixel-based transmissions, to which a first weighted value is applied, and the block-based transmissions to which a second weighted value is applied and interpolation is performed.

8. The apparatus of claim 1 , wherein the airlight estimation unit comprises:

a representative airlight value extracting unit configured to set a pixel value of a brightest pixel in the each block of the previous image or an average of the pixel value of the brightest pixel and pixel values of pixels to the left and right of the brightest pixel as a representative airlight value of the block, extract a brightest representative airlight value among the representative airlight values of the plurality of blocks as airlight of the previous image, and calculate the airlight of the input image using the airlight of the previous image; and

a filter which removes noise from the airlight of the input image.

9. The apparatus of claim 7 , wherein the filter includes an infinite impulse response (IIR) filter to remove the noise from the airlight of the input image.

10. The apparatus of claim 1 , wherein the airlight estimation unit calculates the airlight of the input image and applies the airlight of the input image to calculation of airlight of a next image.

11. A method of processing an image, the method comprising:

calculating a transmission of an input image by synthesizing pixel-based transmissions of current pixels of the current image including a fog component, and block-based transmissions of a plurality of blocks of a previous image, each block comprising a plurality of pixels;

calculating airlight of the input image; and

restoring an image in which, based on the transmission and the airlight, a fog component is removed from the input image.

12. The method of claim 11 , wherein the pixel-based transmissions are calculated by applying a dark channel prior to the current pixels of the current image, and the block-based transmissions are calculated by applying the dark channel prior to the each block of the previous image, and

wherein the airlight is calculated from a brightest pixel value of a brightest block among the plurality of blocks.

13. The method of claim 12 , wherein the block-based transmissions are calculated by using a lowest pixel value among the plurality of pixels in the each block of the previous image.

14. The method of claim 13 , wherein the calculating the block-based transmissions comprises:

dividing the previous image into the plurality of blocks;

extracting the lowest pixel value as a representative pixel value of the each block, by comparing pixel values of the plurality of pixels in the each block; and

calculating the block-based transmissions by using the representative pixel value.

15. The method of claim 14 , the pixel-based transmission and the block-based transmissions are calculated by applying the airlight of the input image.

16. The method of claim 14 further comprising interpolating a transmission of the each block and transmissions of neighboring blocks according to a distance between a center of the each block and the current pixels.

17. The method of claim 12 , wherein, further comprising synthesizing, the pixel-based transmissions, to which a first weighted value is applied, and the block-based transmissions, to which a second weighted value is applied and interpolation is performed, are synthesized.

18. The method of claim 11 , wherein the estimating the airlight comprises:

setting a pixel value of a brightest pixel in the each block of the previous image or an average of the pixel value of the brightest pixel and pixel values of pixels to the left and right of the brightest pixel as a representative airlight value of the block, extracting a brightest representative airlight value among the representative airlight values of the plurality of blocks as the airlight of the previous image;

calculating the airlight of the input image using the airlight of the previous image; and

removing noise from the airlight of the input image.

19. The method of claim 11 , wherein the airlight of the input image is applied to calculation of airlight of a next image.

20. A non-transitory computer readable recording medium having recorded thereon a program for executing the method of claim 11 .

Assignments (8)