Moving object detector and image monitoring system

• US 20020118862A1
• Filed: 02/25/2002
• Published: 08/29/2002
• Est. Priority Date: 02/28/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Sugimoto, Kazuo, Asai, Kohtaro, Kuroda, Shinichi, Ogawa, Fuminobu
• Granted Patent: US 7,082,210 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19667 Details realated to data compression, encryption or encoding, e.g. resolution modes for reducing data volume to lower transmission bandwidth or memory requirements
• CPC Class Codes: G08B 13/19671 Addition of non-video data, i.e. metadata, to video stream
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109

Abstract

A coded stream analyzer (102) variable-length decodes an incoming coded stream and extracts encoding parameters for each macroblock, such as an encoding mode, DCT coefficient values, the amount of codes of DCT coefficients, the amount of codes of each macroblock, and a motion vector, from the coded stream. An effective macroblock identification unit (103) then identifies macroblocks each of which can be contained in a moving object as an effective macroblock by using one or more encoding parameters extracted by the coded stream analyzer (102). A moving object determination unit (104) determines whether or not each of the one or more effective macroblocks identified by the effective macroblock identification unit (103) is contained in a moving object by counting the number of effective macroblocks which are directly adjacent to each of the one or more effective macroblocks or indirectly adjacent to each of the one or more effective macroblocks via one or more other effective macroblocks, and then comparing the number of adjacent effective macroblocks with a predetermined threshold value.

Claims

1. A moving object detector comprising:

an effective macroblock identification unit for identifying one or more candidates for a macroblock that can be contained in an on-screen moving object as one or more effective macroblocks by using an encoding parameter; and

a moving object determination unit for determining whether or not each of the one or more effective macroblocks identified by said effective macroblock identification unit is contained in a moving object based on a number of effective macroblocks (referred to as a number of adjacent effective macroblocks from here on) which are directly adjacent to each of the one or more effective macroblocks or indirectly adjacent to each of the one or more effective macroblocks via one or more other effective macroblocks.

2. The moving object detector according to claim 1, wherein said moving object determination unit counts the number of adjacent effective macroblocks for each of the one or more effective macroblocks identified by said effective macroblock identification unit, and, when the number of adjacent effective macroblocks exceeds a predetermined threshold value, determines that a group of plural effective macroblocks directly or indirectly adjacent to one another and including each of the one or more effective macroblocks is a moving object.

3. The moving object detector according to claim 1, further comprising a coded stream analyzer for analyzing a coded stream obtained by encoding a moving image so as to extract an encoding parameter from the coded stream, and for outputting the encoding parameter to said effective macroblock identification unit.

4. The moving object detector according to claim 1, further comprising an encoding parameter input unit for receiving an encoding parameter generated when a moving image is encoded, and for outputting the encoding parameter to said effective macroblock identification unit.

5. The moving object detector according to claim 1, further comprising a moving object coordinate storage unit for storing on-screen coordinates of each effective macroblock which has been determined as a macroblock contained in a moving object by said moving object determination unit, a motion vector storage unit for storing a motion vector for each effective macroblock which has been determined as a macroblock contained in the moving object, and a coordinate calculation unit for calculating a prediction of the on-screen coordinates of each effective macroblock in a next frame based on the on-screen coordinates of each effective macroblock stored in said moving object coordinates storage unit and the motion vector for each effective macroblock stored in said motion vector storage unit, wherein said moving object determination unit determines whether or not each of the one or more effective macroblocks identified by the effective macroblock identification unit is contained in a moving object by using the one or more effective macroblocks and macroblocks each having a prediction of its on-screen coordinates calculated by said coordinate calculation unit.

6. The moving object detector according to claim 5, wherein said moving object determination unit determines whether or not each of the one or more effective macroblocks identified by the effective macroblock identification unit is contained in a moving object based on the number of adjacent effective macroblocks which are an overlap among a group of plural effective macroblocks directly or indirectly adjacent to one another and including each of the one or more effective macroblocks and the macroblocks each having a prediction of its on-screen coordinates calculated by said coordinate calculation unit.

7. The moving object detector according to claim 5, wherein said moving object determination unit counts the number of adjacent effective macroblocks which are an overlap among a group of plural effective macroblocks directly or indirectly adjacent to one another and including each of the one or more effective macroblocks and the macroblocks each having a prediction of its on-screen coordinates calculated by said coordinate calculation unit, and then determines whether or not each of the one or more effective macroblocks identified by the effective macroblock identification unit is contained in a moving object based on the counted number of adjacent effective macroblocks.

8. The moving object detector according to claim 1, wherein said effective macroblock identification unit identifies a macroblock as an effective macroblock that can be contained in a moving object when an encoding mode of the macroblock extracted as the encoding parameter of the macroblock is an intra coding mode.

9. The moving object detector according to claim 1, wherein said effective macroblock identification unit identifies a macroblock as an effective macroblock that can be contained in a moving object when an encoding mode of the macroblock extracted as the encoding parameter of the macroblock is a motion compensation prediction mode.

10. The moving object detector according to claim 1, wherein said effective macroblock identification unit identifies a macroblock as an effective macroblock that can be contained in a moving object when a number of DCT coefficients of the macroblock extracted as the encoding parameter of the macroblock is equal to or greater than a predetermined threshold value.

11. The moving object detector according to claim 1, wherein said effective macroblock identification unit identifies a macroblock as an effective macroblock that can be contained in a moving object when a sum of codes of AC components of DCT coefficients of the macroblock extracted as the encoding parameter of the macroblock is equal to or greater than a predetermined threshold value.

12. The moving object detector according to claim 1, wherein when an encoding mode of a macroblock extracted as the encoding parameter of the macroblock is a motion compensation prediction mode, said effective macroblock identification unit calculates a norm of a motion vector calculated for the macroblock, and identifies the macroblock as an effective macroblock that can be contained in a moving object when the calculated norm is equal to or greater than a predetermined threshold value.

14. The image monitoring system according to claim 13, wherein when said moving object detector determines that any moving object does not exist in a preceding frame but one or more moving objects exist in a current frame, said moving object detector transmits a signal indicating a request for intra coding to a moving image encoding unit that generates the coded stream by way of the transmission path and said moving image encoding unit then intra-codes following frames of the image when receiving the request signal from said moving object detector.

15. The image monitoring system according to claim 14, wherein said moving image encoding unit intra-codes following frames of the image and also transmits information such as a time and characteristics of the image as metadata by way of the transmission path when receiving the request signal from said moving object detector.

16. The image monitoring system according to claim 14, wherein when said moving object detector detects a moving object, said moving object detector outputs information such as a time and characteristics of the image as metadata.

18. The image monitoring system according to claim 17, wherein only when said moving object detector determines that a moving object exists on a screen, said moving image encoding unit transmits the coded stream by way of the transmission path.

19. The image monitoring system according to claim 17, wherein when said moving object detector determines that any moving object does not exist in a preceding frame but one or more moving objects exist in a current frame, said moving image encoding unit intra-codes following frames of the image.

20. The image monitoring system according to claim 17, wherein only when said moving object detector determines that a moving object exists on a screen, said moving image encoding unit intra-codes following frames of the image and also transmits information such as a time and characteristics of the image as metadata by way of the transmission path.

13. An image monitoring system including a moving image decoding unit for receiving a coded stream obtained by encoding an image generated with a camera by way of a transmission path and for decoding the coded stream, and a monitor for displaying the decoded image obtained by said moving image decoding unit, said system comprising:

a moving object detector including an effective macroblock identification unit for identifying one or more candidates for a macroblock that can be contained in an on-screen moving object as one or more effective macroblocks by using an encoding parameter, and a moving object determination unit for determining whether or not each of the one or more effective macroblocks identified by said effective macroblock identification unit is contained in a moving object based on a number of effective macroblocks which are directly adjacent to each of the one or more effective macroblocks or indirectly adjacent to each of the one or more effective macroblocks via one or more other effective macroblocks.

17. An image monitoring system including a camera for generating an image of a monitor point, and a moving image encoding unit for encoding the image generated by said camera and for outputting the encoded image as a coded stream, said system comprising:

a moving object detector including an effective macroblock identification unit for identifying one or more candidates for a macroblock that can be contained in an on-screen moving object as one or more effective macroblocks by using an encoding parameter; and

a moving object determination unit for determining whether or not each of the one or more effective macroblocks identified by said effective macroblock identification unit is contained in a moving object based on a number of effective macroblocks which are directly adjacent to each of the one or more effective macroblocks or indirectly adjacent to each of the one or more effective macroblocks via one or more other effective macroblocks,

wherein when said moving object detector detects a moving object, said moving object detector transmits a warning signal by way of a transmission path.