System and method for increasing the bit depth of images

• US 9,286,653 B2
• Filed: 08/06/2014
• Issued: 03/15/2016
• Est. Priority Date: 08/06/2014
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Russell, Andrew Ian
• Primary Examiner(s): Seth, Manav
• Application Number:
  US14/452,790
• Publication Number:
  US 20160042498A1
• Time in Patent Office: 587 Days
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/20016 Hierarchical, coarse-to-fine, multiscale or multiresolution image processing; Pyramid transform
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression

Abstract

A method for processing an image having a first bit depth includes performing two or more iterations of a bit depth enhancement operation that increases the bit depth of the image to a second bit depth that is higher than the first bit depth. The bit depth enhancement operation includes dividing the image into a plurality of areas, performing an edge detection operation to identify one or more areas from the plurality of areas that do not contain edge features, and applying a blur to the one or more areas from the plurality of areas that do not contain edge features. In a first iteration of the of the bit depth enhancement operation, the plurality of areas includes a first number of areas, and the number of areas included in the plurality of areas decreases with each subsequent iteration of the bit depth enhancement operation.

Claims

1. A method for processing an image having a first bit depth:

performing two or more iterations of a bit depth enhancement operation that increases the bit depth of the image to a second bit depth that is higher than the first bit depth, the bit depth enhancement operation including;

dividing the image into a plurality of areas,

performing an edge detection operation to identify one or more areas from the plurality of areas that do not contain edge features, and

applying a blur to the one or more areas from the plurality of areas that do not contain edge features,

wherein, in a first iteration of the of the bit depth enhancement operation, the plurality of areas includes a first number of areas, and the number of areas included in the plurality of areas decreases with each subsequent iteration of the bit depth enhancement operation.

2. The method of claim 1, wherein the number of areas included in the plurality of areas decreases by approximately 75 percent with each subsequent iteration of the bit depth enhancement operation.

3. The method of claim 1, wherein dividing the image into a plurality of areas is performed using a constant area size for the first iteration and each subsequent iteration.

4. The method of claim 1, wherein dividing the image into a plurality of areas is performed by using a first area size for the first iteration and increasing the area size for each subsequent iteration.

5. The method of claim 1, wherein each area from the plurality of areas includes a plurality of pixels each having a pixel value, and the edge detection operation includes comparing a maximum pixel value in each area to a minimum pixel value in each area.

6. The method of claim 5, wherein an edge feature is identified when the difference between the maximum pixel value and the minimum pixel value in a respective area from the plurality of areas exceeds a threshold value.

7. The method of claim 1, wherein each area from the plurality of areas includes a plurality of pixels each having a pixel value and applying the blur includes averaging the pixel values in each of the one or more areas that do not contain edge features.

8. An apparatus for processing an image having a first bit depth, comprising:

a memory; and

a processor configured to execute instructions stored in the memory to;

perform two or more iterations of a bit depth enhancement operation that increases the bit depth of the image to a second bit depth that is higher than the first bit depth, the bit depth enhancement operation including;

dividing the image into a plurality of areas,

performing an edge detection operation to identify one or more areas from the plurality of areas that do not contain edge features, and

applying a blur to the one or more areas from the plurality of areas that do not contain edge features,

wherein, in a first iteration of the of the bit depth enhancement operation, the plurality of areas includes a first number of areas, and the number of areas included in the plurality of areas decreases with each subsequent iteration of the bit depth enhancement operation.

9. The apparatus of claim 8, wherein the number of areas included in the plurality of areas decreases by approximately 75 percent with each subsequent iteration of the bit depth enhancement operation.

10. The apparatus of claim 8, wherein dividing the image into a plurality of areas is performed using a constant area size for the first iteration and each subsequent iteration.

11. The apparatus of claim 8, wherein dividing the image into a plurality of areas is performed by using a first area size for the first iteration and increasing the area size for each subsequent iteration.

12. The apparatus of claim 8, wherein each area from the plurality of areas includes a plurality of pixels each having a pixel value, and the edge detection operation includes comparing a maximum pixel value in each area to a minimum pixel value in each area.

13. The apparatus of claim 12, wherein an edge feature is identified when the difference between the maximum pixel value the minimum pixel value in a respective area from the plurality of areas exceeds a threshold value.

14. The apparatus of claim 8, wherein each area from the plurality of areas includes a plurality of pixels each having a pixel value and applying the blur includes averaging the pixel values in each of the one or more areas that do not contain edge features.

15. A non-transitory computer-readable storage device including program instructions executable by one or more processors that, when executed, cause the one or more processors to perform operations for processing an image having a first bit depth, the operations comprising:

performing two or more iterations of a bit depth enhancement operation that increases the bit depth of the image to a second bit depth that is higher than the first bit depth, the bit depth enhancement operation including;

dividing the image into a plurality of areas,

performing an edge detection operation to identify one or more areas from the plurality of areas that do not contain edge features, and

applying a blur to the one or more areas from the plurality of areas that do not contain edge features,

wherein, in a first iteration of the of the bit depth enhancement operation, the plurality of areas includes a first number of areas, and the number of areas included in the plurality of areas decreases with each subsequent iteration of the bit depth enhancement operation.

16. The non-transitory computer-readable storage device of claim 15, wherein the number of areas included in the plurality of areas decreases by approximately 75 percent with each subsequent iteration of the bit depth enhancement operation.

17. The non-transitory computer-readable storage device of claim 15, wherein dividing the image into a plurality of areas is performed using a constant area size for the first iteration and each subsequent iteration.

18. The non-transitory computer-readable storage device of claim 15, wherein dividing the image into a plurality of areas is performed by using a first area size for the first iteration and increasing the area size for each subsequent iteration.

19. The non-transitory computer-readable storage device of claim 15, wherein each area from the plurality of areas includes a plurality of pixels each having a pixel value, and the edge detection operation includes comparing a maximum pixel value in each area to a minimum pixel value in each area.

20. The non-transitory computer-readable storage device of claim 19, wherein an edge feature is identified when the difference between the maximum pixel value and the minimum pixel value in a respective area from the plurality of areas exceeds a threshold value.

21. The non-transitory computer-readable storage device of claim 15, wherein each area from the plurality of areas includes a plurality of pixels each having a pixel value and applying the blur includes averaging the pixel values in each of the one or more areas that do not contain edge features.