METHOD OF GENERATING A BLOCKINESS INDICATOR FOR A VIDEO SIGNAL

• US 20090067511A1
• Filed: 09/03/2008
• Published: 03/12/2009
• Est. Priority Date: 09/07/2007
• Status: Active Grant

• Current Assignee: Evertz Microsystems Ltd. (Evertz Technologies Limited)
• Original Assignee: Evertz Microsystems Ltd. (Evertz Technologies Limited)
• Inventors: Patel, Rakesh, Wei, Jeff
• Granted Patent: US 9,131,213 B2
• Time in Patent Office: Days
• US Class Current: 375/240.290
• CPC Class Codes: H04N 17/004 for digital television systems
• CPC Class Codes: H04N 19/167 Position within a video image, e.g. region of interest [ROI]
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/66 involving data partitioning, i.e. separation of data into packets or partitions according to importance
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/865 with detection of the former encoding block subdivision in decompressed video
• CPC Class Codes: H04N 19/88 involving rearrangement of data among different coding units, e.g. shuffling, interleaving, scrambling or permutation of pixel data or permutation of transform coefficient data among different blocks
• CPC Class Codes: H04N 7/0155 using pixel blocks

Abstract

The described embodiments relate to methods and systems for detecting the blockiness of a video signal comprised of a number of pixels. The method includes the steps of calculating a total number of pixels in the video signal in flat blocks and visible block edge transitions, and generating a blockiness indicator from the total number of pixels in flat blocks and visible block edge transitions. The step of calculating the total number of pixels in flat blocks and the total number of pixels in visible block edge transitions may include calculating differential values for each pixel in the video signal, analyzing the differential values to determine if the pixel is part of a transition and/or a flat area and then counting the number of pixels in flat blocks and visible block edge transitions to produce a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions.

Claims

1. A method of measuring the blockiness of a video signal comprised of a plurality of pixels the method comprising the steps of:

calculating a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions in the video signal; and

generating at least one blockiness indicator from the total number of pixels in flat blocks and the total number of pixels in visible block edge transitions.

2. The method of claim 1 further comprising the step of selecting a region of interest from the video signal prior to calculating and generating.

3. The method of claim 1 wherein the calculation step includes:

for each pixel in the video signal

calculating differential values for the pixel;

analyzing the differential values to determine if the pixel is part of a transition and if the pixel is part of a flat area;

counting the number of pixels in flat blocks and the number of pixels in visible block edge transitions to produce a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions;

4. The method of claim 3 wherein calculating differential values includes selecting the n*2−

1 pixels surrounding the pixel of interest wherein n is any odd integer greater than one.

5. The method of claim 4 wherein n is equal to three.

6. The method of claim 1 wherein the at least blockiness indicator includes a block border indicator.

7. The method of claim 1 wherein the at least one blockiness indicator includes a flat area indicator.

8. The method of claim 1 wherein the at least one blockiness indicator includes a flat block indicator.

9. The method of claim 1 wherein three blockiness indicators are generated.

10. The method of claim 9 wherein the three blockiness indicators are a block border indicator, a flat area indicator and a flat block indicator.

11. The method of claim 1 wherein the calculation step is performed using the luma values of the video signal.

12. The method of claim 1 further comprising the step of recursive filtering the at least one blockiness indicator.

13. The method of claim 1 further comprising the step of generating a blockiness alarm if the at least one blockiness indicator surpasses a configurable threshold.

14. A video signal compression system comprising:

a video source for producing a video signal comprised of a plurality of pixels;

a compression module for compressing the video signal at a compression level into a compressed video signal;

a decompression module for decompressing the compressed video signal into a decompressed video signal; and

a blockiness detection module configured to;

calculate a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions in the decompressed video signal; and

generate at least one blockiness indicator from the total number of pixels in flat blocks and the total number of pixels in visible block edge transitions.

wherein the compression module adjusts the compression level based on the at least blockiness indicator.

15. The system of claim 14 wherein the blockiness detector is further configured to select a region of interest from the decompressed video signal prior to performing the calculation and generation

16. The system of claim 14 wherein the calculation includes:

for each pixel in the decompressed video signal

calculating differential values for the pixel;

analyzing the differential values to determine if the pixel is part of a transition and if the pixel is part of a flat area;

counting the number of pixels in flat blocks and the number of pixels in visible block edge transitions to produce a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions;

17. The system of claim 16 wherein calculating differential values includes selecting the n*2−

1 pixels surrounding the pixel of interest wherein n is any odd integer greater than one.

18. The system of claim 17 wherein n is equal to three.

19. The system of claim 14 wherein the calculation is performed using the luma values of the decompressed video signal.

20. The system of claim 14 wherein the blockiness detector is further configured to perform recursive filtering of the blockiness indicator.

21. The system of claim 14 further comprising a display module for displaying the blockiness indicator.

22. The system of claim 14 further comprising the step of generating a blockiness alarm if the at least one blockiness indicator surpasses a configurable threshold.

23. A video signal compression system comprising:

a video source for producing a video signal comprised of a plurality of pixels;

a compression module for compressing the video signal at a compression level into a compressed video signal;

a decompression module for decompressing the compressed video signal into a decompressed video signal; and

a first blockiness detection module configured to;

calculate a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions in the decompressed video signal; and

generate at least one decompressed video signal blockiness indicator from the total number of pixels in flat blocks and the total number of pixels in visible block edge transitions,

a second blockiness detection module configured to generate a blockiness indicator for the video signal,

calculate a total number of pixels in flat blocks and a total number of pixels in visible block edge transitions in the video signal; and

generate at least one video signal blockiness indicator from the total number of pixels in flat blocks and the total number of pixels in visible block edge transitions.

wherein the compression module adjusts the compression level based on the decompressed video signal blockiness indicator and the video signal blockiness indicator.