Adaptive subpixel-based downsampling and filtering using edge detection

1. A method, comprising:

determining, by a system comprising a processor, a luminance gradient of a block of pixels in four directions;

determining an edge direction of the block based on the luminance gradient of the block; and

in response to the determining the edge direction of the block, selecting alternate subpixels of the block of pixels based on the edge direction of the block.

2. The method of claim 1 , further comprising:

computing a color gradient, in the four directions, of a subpixel of the alternate subpixels;

in response to the computing the color gradient, determining an edge direction of the subpixel; and

filtering the alternate subpixels in response to the determining the edge direction of the subpixel.

3. The method of claim 2 , wherein the filtering the alternate subpixels comprises:

selecting a low pass filter associated with an infinite impulse response; and

filtering the alternate subpixels utilizing the low pass filter.

4. The method of claim 1 , wherein the determining the luminance gradient comprises determining the luminance gradient in at least one of a horizontal direction, a vertical direction, a left diagonal direction, or a right diagonal direction.

5. The method of claim 1 , wherein the determining the luminance gradient in the four directions comprises:

determining the luminance gradient in a horizontal direction, a vertical direction, a left diagonal direction, and a right diagonal direction; and

selecting a minimum luminance gradient with respect to the horizontal direction, the vertical direction, the left diagonal direction, and the right diagonal direction.

6. The method of claim 1 , wherein the selecting the alternate subpixels comprises selecting the alternate subpixels in a direction opposite the edge direction of the block.

7. The method of claim 2 , wherein the computing the color gradient comprises computing the color gradient in at least one of a horizontal direction, a vertical direction, a left diagonal direction, or a right diagonal direction.

8. The method of claim 2 , wherein the computing the color gradient comprises:

computing the color gradient in a horizontal direction, a vertical direction, a left diagonal direction, and a right diagonal direction; and

selecting a minimum value of the color gradient with respect to the horizontal direction, the vertical direction, the left diagonal direction, and the right diagonal direction.

9. The method of claim 2 , wherein the computing the color gradient comprises filtering the alternate subpixels in a direction opposite the edge direction of the subpixel.

10. The method of claim 5 , wherein the determining the edge direction of the block comprises selecting the edge direction of the block based on the minimum luminance gradient.

11. The method of claim 8 , wherein the determining the edge direction of the subpixel comprises selecting the edge direction of the subpixel based on the minimum value of the color gradient.

12. A system, comprising:

a memory to store instructions; and

a processor, coupled to the memory, that executes or facilitates execution of the instructions to at least:

determine at least one gradient of a luminance of a block of pixels based on at least one direction;

determine a selected direction of the block based on the at least one gradient of the luminance; and

select alternate subpixels of the block based on the selected direction of the block.

13. The system of claim 12 , wherein the processor further executes or facilitates the execution of the instructions to:

determine the at least one gradient of the luminance in a horizontal direction, a vertical direction, a left diagonal direction, and a right diagonal direction; and

select the direction of the block associated with a direction related to the minimum gradient of the at least one gradient of the luminance.

14. The system of claim 12 , wherein the processor further executes or facilitates the execution of the instructions to select the alternate subpixels in a direction opposite the selected direction of the block.

15. The system of claim 12 , wherein the processor further executes or facilitates the execution of the instructions to:

determine at least one color gradient of a subpixel of the alternate subpixels based on the at least one direction;

determine a direction of the subpixel based on the at least one color gradient; and

filter the alternate subpixels based on the direction of the subpixel.

16. The system of claim 15 , wherein the processor further executes or facilitates the execution of the instructions to:

select a low pass filter associated with an infinite sinc function; and

filter the alternate subpixels utilizing the low pass filter.

17. The system of claim 15 , wherein the processor further executes or facilitates the execution of the instructions to:

determine the at least one color gradient of the subpixel in a horizontal direction, a vertical direction, a left diagonal direction, and a right diagonal direction;

determine a minimum gradient of the at least one color gradient; and

select the direction of the subpixel based on the minimum gradient of the at least one color gradient.

18. The system of claim 17 , wherein the processor further executes or facilitates the execution of the instructions to filter the alternate subpixels in another direction opposite the direction of the subpixel.

19. A method, comprising:

determining, by a system comprising a processor, a gradient of a luminance value of a block of pixels in at least one direction;

determining an edge direction of the block in response to the determining the gradient of the luminance value; and

selecting alternate subpixels of the block in response to the determining the edge direction of the block.

20. The method of claim 19 , further comprising:

selecting the block from image information.

21. The method of claim 19 , further comprising:

obtaining luminance information of the block from color domain information of the block.

22. The method of claim 19 , wherein the determining the gradient comprises determining the gradient in a horizontal direction, a vertical direction, a left diagonal direction, and a right diagonal direction to obtain determined gradients.

23. The method of claim 22 , wherein the determining the edge direction of the block comprises:

determining a minimum gradient of the determined gradients; and

selecting the edge direction of the block based on the minimum gradient.

24. The method of claim 19 , further comprising:

determining a gradient of a color value of a subpixel of the alternate subpixels in the at least one direction;

determining an edge direction of the subpixel in response to the determining the gradient of the color value; and

applying a filter to the alternate subpixels in response to the determining the edge direction of the subpixel.

25. The method of claim 24 , wherein the applying the filter comprises:

selecting a low pass filter of an infinite impulse response; and

applying the low pass filter to the alternate subpixels.

26. An apparatus, comprising:

means for selecting a block of pixels from image information;

means for determining a gradient of a luminance of the block in four directions; and

means for sampling alternate subpixels of the block based on an output of the means for the determining the gradient of the luminance of the block.

27. The apparatus of claim 26 , further comprising:

means for determining a color gradient of a subpixel of the alternate subpixels in the four edge directions; and

means for filtering the alternate subpixels based on an output of the means for the determining the color gradient.