Method and device for calculating blur in video images

• US 8,823,873 B2
• Filed: 10/10/2009
• Issued: 09/02/2014
• Est. Priority Date: 10/10/2009
• Status: Expired due to Fees

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Liu, Debing, Chen, Zhibo, Gu, Xaiodong, Xu, Feng
• Primary Examiner(s): Natnael, Paulos M
• Application Number:
  US13/500,921
• Publication Number:
  US 20120268652A1
• Time in Patent Office: 1,788 Days
• Field of Search: 348/446, 348/447, 348/448, 348/451, 348/452, 348/607, 348/614, 348/618, 375/240.01, 375/240.24, 375/240.26, 382/286, 382/302, 382/199
• US Class Current: 348/446
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20004 Adaptive image processing
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/30168 Image quality inspection
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 7/012 Conversion between an interlaced and a progressive signal for graphics images G09G2310/0229

Abstract

Blur is one of the most important features related to image quality. Accurately estimating the blur level of an image is a great help to accurately evaluate its quality. A method for calculating blur of video images comprises calculating a horizontal blur value, and determining characteristic parameters of the video images, including at last progressive/interlaced and spatial resolution level. If the video images are progressive, also a vertical blur value is calculated, and combined with the horizontal blur value. The next step is normalizing the horizontal blur value, or the combined horizontal and vertical blur value, according to predefined min and max values, wherein the min and max values are adapted to the spatial resolution level.

Claims

1. A method for calculating blur of video images, comprising steps of

calculating a horizontal blur value;

determining characteristic parameters of the video images, including at least progressive/interlaced and spatial resolution level;

if the video images are progressive, calculating also a vertical blur value and combining it with the horizontal blur value; and

normalizing the horizontal blur value, or the combined horizontal and vertical blur value, according to predefined minimum and maximum values, wherein the minimum and maximum values are adapted to the spatial resolution level,

wherein calculating a blur value comprises calculating a local variance around a current pixel and wherein the current pixel is excluded from blur cancellation if the local variance is above a maximum threshold or below a minimum threshold.

2. Method according to claim 1, wherein calculating a horizontal blur value is performed on image areas around the centers of vertical macroblock edges.

3. Method according to claim 2, wherein the local variance for the horizontal blur value is calculated from pixels on a vertical line and pixels on a horizontal line, wherein more pixels from the horizontal line than from the vertical line are used, and wherein said center of a horizontal macroblock edge is a member of both lines.

4. Method according to claim 1, wherein calculating a vertical blur value is performed on image areas around the centers of horizontal macroblock edges.

5. Method according to 1, wherein one or more of the characteristic parameters of the video images are obtained through a user interface or from a memory after being input through a user interface.

6. Method according to claim 1, wherein one or more of the characteristic parameters of the video images are obtained through a machine interface from a video decoder.

7. Method according to claim 1, wherein one or more of the characteristic parameters of the video images are obtained through metadata associated with the video images.

8. A non-transitory computer program product having stored thereon instructions that when executed on a computer cause the computer to execute a method for calculating blur of video images, the method comprising the steps of:

calculating a horizontal blur value;

determining characteristic parameters of the video images, including at least progressive/interlaced and spatial resolution level;

if the video images are progressive, calculating also a vertical blur value and combining it with the horizontal blur value; and

normalizing the horizontal blur value, or the combined horizontal and vertical blur value, according to predefined minimum and maximum values, wherein the minimum and maximum values are adapted to the spatial resolution level,

wherein calculating a blur value comprises calculating a local variance around a current pixel and wherein the current pixel is excluded from blur cancellation if the local variance is above a maximum threshold or below a minimum threshold.