DCT BASED BLACK FRAME DETECTION USING VARYING BLOCK SIZE

• US 20140118622A1
• Filed: 10/25/2013
• Published: 05/01/2014
• Est. Priority Date: 10/29/2012
• Status: Abandoned Application

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: N., Rickesh T.
• Application Number:
  US14/063,887
• Publication Number:
  US 20140118622A1
• Time in Patent Office: Days
• US Class Current: 348/671
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/20052 Discrete cosine transform [DCT]
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: H04N 19/48 using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513
• CPC Class Codes: H04N 21/44008 involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 5/147 Scene change detection

Abstract

A video detector that detects black frames in a video includes a grayscale converter, a parser for parsing the grayscale video into a sequence of individual frames, a sub-frame parser for parsing frames of an uneven block size into two or more sub-frames, and a DCT calculator. The detector extracts a DC component or AC component, or both, of the generated DCT and then compares them against respective threshold values. The individual frames are identified as a black frame based on a comparison between the selected component and the threshold value. Methods of detecting black frames based on DC components and AC components are also described.

Claims

1. A video detector for detecting black frames in a video that includes a number of individual sequential frames, comprising:

an input for accepting the video;

a grayscale converter for converting the video to grayscale;

a parser for parsing the grayscale video into a sequence of individual frames;

a sub-frame parser for parsing those individual frames that do not have a size of an even block size into one or more sub-frames;

a DCT calculator for generating a DCT of a frame or of a sub-frame;

a DC component extractor for extracting a DC component of the generated DCT;

a comparator structured to evaluate the extracted DC component against a DC component threshold value; and

an identifier structured to indicate the individual frame as a black frame based on a comparison between the selected DC component and the threshold value.

2. The video detector for detecting black frames according to claim 1 in which the even block size is 32×

32.

3. The video detector for detecting black frames according to claim 1 in which the DCT calculator is structured to generate a DCT of a frame and of one or more sub-frames.

4. The video detector for detecting black frames according to claim 1 in which the sub-frame parser is structured to, for those individual frames that do not have a size of the even block size:

parse a main portion of the individual frame into a main sub-frame having block sizes of 32×

32;

parse a right portion of the individual frame into a right frame having block sizes of 8×

8; and

parse a bottom portion of the individual frame into a right frame having block sizes of 8×

8.

5. The video detector for detecting black frames according to claim 1, further comprising:

an RGB converter structured to convert the video into RGB components.

6. The video detector for detecting black frames according to claim 1, further comprising:

an AC component extractor for extracting one or more AC components of the generated DCT, and in which

the comparator is also structured to evaluate the extracted one or more AC components against an AC component threshold value.

7. The video detector for detecting black frames according to claim 1 in which the DC component value is programmable.

8. The video detector for detecting black frames according to claim 6 in which the AC component value is programmable.

9. The video detector for detecting black frames according to claim 6 in which the identifier is structured to indicate the individual frame as a black frame when all of the AC components are zero.

10. The video detector for detecting black frames according to claim 6 in which

at least one of the grayscale converter, parser, sub-frame parser, DCT calculator, DC component extractor, comparator, and identifier are functions of a programmed processor.

11. A method for detecting black frames in a video that includes a number of individual sequential frames, the method comprising:

converting the video to grayscale;

parsing the grayscale video into a sequence of individual frames;

parsing those individual frames that do not have a size of an even block size into one or more sub-frames;

generating a DCT of a frame or of a sub-frame;

extracting a DC component of the calculated DCT; and

evaluating the selected DC component against a DC component threshold value.

12. The method for detecting black frames according to claim 11, further comprising indicating the individual frame as a black frame based on a comparison between the selected DC component and the threshold value.

13. The method for detecting black frames according to claim 11 in which the even block size is 32×

32.

14. The method for detecting black frames according to claim 11, in which generating a DCT of a frame or a sub frame comprises generating a DCT of a frame and one or more sub-frames.

15. The method for detecting black frames according to claim 11, in which parsing those individual frames that do not have a size of an even block size into one or more sub-frames comprises:

parsing a main portion of the individual frame into a main sub-frame having block sizes of 32×

32;

parsing a right portion of the individual frame into a right frame having block sizes of 8×

8; and

parsing a bottom portion of the individual frame into a right frame having block sizes of 8×

8.

16. The method for detecting black frames according to claim 11, further comprising:

converting the video into RGB components.

17. The method for detecting black frames according to claim 11, further comprising:

extracting one or more AC components of the generated DCT; and

evaluating the selected one or more AC components against an AC component threshold value.

18. The method for detecting black frames according to claim 11, further comprising:

setting the DC component value.

19. The method for detecting black frames according to claim 11, further comprising:

setting the AC component value.