Method and device for detecting transitions in a video sequence, method and device for coding, computer program products and corresponding storage means

• US 7,990,477 B2
• Filed: 10/03/2006
• Issued: 08/02/2011
• Est. Priority Date: 10/03/2005
• Status: Active Grant

• Current Assignee: MK Systems USA Inc.
• Original Assignee: Envivio France
• Inventors: Person, Tanguy, Kypreos, Jean, Guionnet, Thomas
• Primary Examiner(s): DIEP, NHON THANH
• Application Number:
  US11/542,632
• Publication Number:
  US 20070085931A1
• Time in Patent Office: 1,764 Days
• Field of Search: None
• US Class Current: 348/701
• CPC Class Codes: H04N 19/573 Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/87 involving scene cut or scene change detection in combination with video compression
• CPC Class Codes: H04N 5/147 Scene change detection

Abstract

Method and apparatus for detecting transitions in a video sequence, which include detecting an abrupt transition including, for each image I_t−2k included in said video sequence and with a processing time rank t−2k: calculating a first distance D(I_t−k), between an image I_t−k and a reference image for said image I_t−k, which precedes said image I_t−k in the video sequence; calculating a second distance D(I_t−2k), between an image I_t−2k and a reference image for said image I_t−2k, which precedes said image I_t−2k in the video sequence; calculating a third distance D(I_t−3k), between an image I_t−3k and a reference image for said image I_t−3k, which precedes said image I_t−3k in the video sequence; calculating a criterion C′ indicating whether said second distance D(I_t−2k) is significantly greater than the largest of the first and third distances, D(I_t−k) and D(I_t−3k); deciding, according to said criterion C′, on the belonging of the image I_t−2k to an abrupt transition.

Claims

1. A method for detecting transitions in a video sequence, the method comprising detecting an abrupt transition including the following steps, for each image I_t−

2k included in said video sequence and with a processing time rank t−

2k;

calculation of a first distance D(I<sub>t−

k</sub>), between an image I<sub>t−

k</sub> and a reference image for said image I<sub>t−

k</sub>, which precedes said image I<sub>t−

k</sub> in the video sequence;

calculation of a second distance D(I<sub>t−

2k</sub>), between an image I<sub>t−

2k</sub> and a reference image for said image I<sub>t−

2k</sub>, which precedes said image I<sub>t−

2k</sub> in the video sequence;

calculation of a third distance D(I<sub>t−

3k</sub>), between an image I<sub>t−

3k</sub> and a reference image for said image I<sub>t−

3k</sub>, which precedes said image I<sub>t−

3k</sub> in the video sequence;

calculation of a criterion C′

indicating whether said second distance D(I<sub>t−

2k</sub>) is significantly greater than the largest of the first and third distances, D(I<sub>t−

k</sub>) and D(I<sub>t−

3k</sub>);

decision, according to said criterion C′

, on the belonging of the image I<sub>t−

2k</sub> to an abrupt transition.

2. The method according to claim 1, and further comprising choosing the reference image for each given image, comprising choosing the image that immediately precedes said given image in the video sequence.

3. The method according to claim 1, and further comprising choosing the reference image for each given image, including the following steps:

obtaining an initial list L1 of possible reference images for said given image, said initial list L1 including N images that precede said given image in the video sequence, with N≧

2; and

selection of a reference image among the N possible reference images included in the initial list LI.

4. The method according to claim 3, characterised in that said step of selecting a reference image includes the following steps:

for each of the N reference images, calculation of a distance between the given image and said reference image;

selection of the reference image of which the distance with respect to the given image is the smallest.

5. The method according to claim 4, wherein the distance between the given image and said reference image includes a first parameter obtained by a measurement of the distance between the content of the given image and the content of the reference image, or between the content of a reduced version of the current image and the content of a reduced version of the reference image.

6. The method according to claim 5, wherein the distance between the given image and said reference image includes a second parameter proportional to a time distance between the given image and the reference image.

7. The method according to claim 1, wherein, if two reference images have a same distance with respect to the given image, the reference image closest in time to the given image is considered to have a shorter distance than the other reference image.

8. The method according to claim 1, wherein said criterion C′

is mathematically expressed by an equation belonging to the group including;

9. The method according to claim 1, characterised in that said decision step includes the following steps:

comparison of said criterion C′

with a first threshold S1′

;

if said criterion C′

is less than or equal to the first threshold S1′

, then the image I<sub>t−

2k</sub> is declared not to be an abrupt transition;

if said criterion C′

is greater than the first threshold S1′

, comparison of said second distance D(I<sub>t−

2k</sub>), between the image I<sub>t−

2k</sub> and its reference image, with a second threshold S2′

;

if said second distance D(I<sub>t−

2k</sub>) is less than or equal to the second threshold S2′

, then the image I<sub>t−

2k</sub> is declared not to be an abrupt transition; and

if said second distance D(I<sub>t−

2k</sub>) is greater than the second threshold S2′

, then the image I<sub>t−

2k</sub> is declared to be an abrupt transition.

10. The method according to claim 3, and further comprising detecting a flash image detection based on the reference image selected, and wherein said decision, according to said criterion C′

, on the belonging of the image I<sub>t−

2k</sub> to an abrupt transition includes the following step;

if the image I<sub>t−

2k</sub> is declared to be a flash image in said flash image detection step, then the image I<sub>t−

2k</sub> is declared not to be an abrupt transition.

11. The method according to claim 10, wherein detecting said flash image includes determining a list LF of at least one flash image, capable of being empty and including any reference image from the initial list LI, which is placed in time between the given image and said reference image selected.

12. The method according to claim 1, wherein said decision, according to said criterion C′

, on the belonging of the image I<sub>t−

2k</sub> to an abrupt transition includes the following step;

if the image I<sub>t−

2k</sub> or the image I<sub>t−

3k</sub> is declared to belong to a gradual transition, in said gradual transition detection step, then the image I<sub>t−

2k</sub> is declared not to be an abrupt transition.

13. A method comprising coding a video sequence, which includes a phase of detecting transitions in said video sequence according to the method of claim 1.

14. A storage device, which is computer readable, wherein the storage device comprises a set of stored instructions executable by a computer in order to detect an abrupt transition including the following steps, for each image I_t−

2k included in a video sequence and with a processing time rank t−

2k;

calculating a first distance D(I<sub>t−

k</sub>), between an image I<sub>t−

k</sub> and a reference image for said image I<sub>t−

k</sub>, which precedes said image I<sub>t−

k</sub> in the video sequence;

calculating a second distance D(I<sub>t−

2k</sub>), between an image I<sub>t−

2k</sub> and a reference image for said image I<sub>t−

2k</sub>, which precedes said image I<sub>t−

2k</sub> in the video sequence;

calculating a third distance D(I<sub>t−

3k</sub>), between an image I<sub>t−

3k</sub> and a reference image for said image I<sub>t−

3k</sub>, which precedes said image I<sub>t−

3k</sub> in the video sequence;

calculating a criterion C′

indicating whether said second distance D(I<sub>t−

2k</sub>) is significantly greater than the largest of the first and third distances, D(I<sub>t−

k</sub>) and D(I<sub>t−

3k</sub>);

deciding, according to said criterion C′

, on the belonging of the image I<sub>t−

2k</sub> to an abrupt transition; and

outputting an indication whether the image I<sub>t−

2k</sub> belongs to the abrupt transition.

15. The storage device of claim 14 and further comprising stored program code instructions for executing the following steps when said program is run on the computer:

coding a video sequence, which includes a phase of detecting transitions in said video sequence according to the program code instructions of claim 14.

16. A device for detecting transitions in a video sequence, the device comprising:

means for calculating a first distance D(I<sub>t−

k</sub>), between an image I<sub>t−

k</sub> and a reference image for said image I<sub>t−

k</sub>, which precedes said image I<sub>t−

k</sub> in the video sequence;

means for calculating a second distance D(I<sub>t−

2k</sub>), between an image I<sub>t−

2k</sub> and a reference image for said image I<sub>t−

2k</sub>, which precedes said image I<sub>t−

2k</sub> in the video sequence;

means for calculating a third distance D(I<sub>t−

3k</sub>), between an image I<sub>t−

3k</sub> and a reference image for said image I<sub>t−

3k</sub>, which precedes said image I<sub>t−

3k</sub> in the video sequence;

means for calculating a criterion C′

indicating whether said second distance D(I<sub>t−

2k</sub>) is significantly greater than the largest of the first and third distances, D(I<sub>t−

k</sub>) and D(I<sub>t−

3k</sub>); and

means for deciding, according to said criterion C′

, on the belonging of the image I<sub>t−

2k</sub> to an abrupt transition.

17. A coding device of the type including a video encoder and a transition detection device according to claim 16, said transition detection device cooperating with said video encoder or being at least partially included in said video encoder.