METHOD AND DEVICE FOR COMPRESSING MOVING IMAGE

• US 20110176027A1
• Filed: 03/30/2011
• Published: 07/21/2011
• Est. Priority Date: 10/29/2008
• Status: Active Grant

• Current Assignee: Panasonic Semiconductor Solutions Co., Ltd. (Winbond Electronics Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: TANAKA, Yasuharu
• Granted Patent: US 8,705,628 B2
• Time in Patent Office: Days
• US Class Current: 348/222.1
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A still block detector is provided at a stage before a moving image encoder. The still block detector divides a frame to be processed into a plurality of blocks, sorts the blocks in the frame in ascending order of movement amount, and sets the first one or more blocks the number of which is specified by a “corresponding block setting number” input from the outside of an encoding device, to “still blocks.” For the still blocks, the moving image encoder performs an inter-encoding process with respect to a moving image by forcibly setting motion vectors to zeros without performing a motion search or by forcibly setting DCT coefficients to zeros without performing DCT or quantization.

Claims

1. A method for encoding a moving image using motion vectors which are generated by dividing a frame to be processed into a plurality of blocks and performing a motion search with respect to each of the plurality of blocks using an input image and an already encoded reference image, the method comprising the steps of:

selecting S blocks from the plurality of blocks in the frame, where S is an integer of one or more; and

encoding the moving image by forcibly replacing the motion vectors with zeros without performing the motion search, with respect to the selected S blocks.

3. The method of claim 1 or 2, further comprising the step of:

detecting image movement amounts with respect to all or a portion of the plurality of blocks in the frame,

wherein

movement amounts of the all or a portion of the plurality of blocks are compared to select S blocks having the smallest image movement amounts.

4. The method of claim 3, further comprising the step of:

reducing a frame image by a factor of n, where n is an integer of two or more,

wherein

the reduced image is used to detect the image movement amounts.

5. The method of claim 1 or 2, wherein the encoding the moving image by forcibly replacing the DCT coefficients with zeros is performed only r−

1 times with respect to r frames, where r is an integer of two or more.

6. The method of claim 5, further comprising the steps of:

correcting the amount of data to be encoded by multiplying the amount of data to be encoded of a previous frame by the total number of blocks/S; and

performing a bit rate control based on the corrected amount of data to be encoded.

2. A method for encoding a moving image using DCT coefficients which are generated by dividing a frame to be processed into a plurality of blocks and performing DCT and quantization with respect to each of the plurality of blocks, the method comprising the steps of:

selecting S blocks from the plurality of blocks in the frame, where S is an integer of one or more; and

encoding the moving image by forcibly replacing the DCT coefficients with zeros without performing the DCT and the quantization, with respect to the selected S blocks.

7. A method for encoding a moving image using motion vectors which are generated by dividing a frame to be processed into a plurality of blocks and performing a motion search with respect to each of the plurality of blocks using an input image and an already encoded reference image, the method comprising:

a first step of detecting and storing image movement amounts into a movement amount storage;

a second step of comparing the image movement amounts stored in the movement amount storage to select S blocks having the smallest image movement amounts from the plurality of blocks in the frame, where S is an integer of one or more; and

a third step of encoding the moving image by forcibly replacing the motion vectors with zeros without performing the motion search, with respect to the selected S blocks, wherein

at the same time that the third step is performed with respect to one frame, movement amounts to be used in the third step at the next frame is obtained in the first and second steps.

9. The method of claim 7 or 8, wherein

the movement amount storage can store only movement amount information corresponding to the S blocks, and

when a result of the detection of a movement amount is stored, the movement amount and a movement amount already stored in the movement amount storage are compared, and if the movement amount is smaller than the already-stored movement amount, the movement amount is stored into the movement amount storage to update the movement amount storage, and if the movement amount is larger than the already-stored movement amount, the movement amount is not stored into the movement amount storage and the movement amount storage is not updated.

8. A method for encoding a moving image using DCT coefficients which are generated by dividing a frame to be processed into a plurality of blocks and performing DCT and quantization with respect to each of the plurality of blocks, the method comprising:

a first step of detecting and storing image movement amounts into a movement amount storage;

a second step of comparing the image movement amounts in the movement amount storage, and selecting S blocks having the smallest image movement amounts from the plurality of blocks in the frame, where S is an integer of one or more; and

a third step of encoding the moving image by forcibly replacing the DCT coefficients with zeros without performing the DCT and the quantization, with respect to the selected S blocks,

wherein

at the same time that the third step is performed with respect to one frame, movement amounts to be used in the third step at the next frame are obtained in the first and second steps.

10. A device for encoding a moving image using motion vectors which are generated by dividing a frame to be processed into a plurality of blocks and performing a motion search with respect to each of the plurality of blocks using an input image and an already encoded reference image, the device comprising:

an input image reducer configured to reduce the input image to be encoded, by a factor of n, where n is an integer of one or more, to generate a reduced input image;

a reference image reducer configured to reduce the already encoded reference image by a factor of n to generate a reduced reference image;

a movement amount detector configured to receive the reduced input image and the reduced reference image from the input image reducer and the reference image reducer, and detect a movement amount with respect to each of the plurality of blocks;

a movement amount storage configured to store the movement amounts detected by the movement amount detector;

a still block selector configured to compare the movement amounts stored in the movement amount storage to select S blocks having the smallest movement amounts, where S is an integer of one or more; and

a moving image encoder configured to encode the moving image by forcibly replacing the motion vectors with zeros without performing the motion search, with respect to the selected S blocks.

12. The device of claim 10 or 11, wherein

the encoding the moving image by forcibly replacing the DCT coefficients with zeros is performed only r−

1 times with respect to r frames, where r is an integer of two or more.

13. The device of claim 12, further comprising:

a section configured to correct the amount of data to be encoded by multiplying the amount of data to be encoded of a previous frame by the total number of blocks/S, and perform a bit rate control based on the corrected amount of data to be encoded.

14. An imaging system comprising:

an image processing circuit including the device of claim 10 or 11;

a sensor configured to convert image light into an image signal;

an optical system configured to image incident image light onto the sensor; and

a converter configured to convert the image signal into digital data and output the digital data to the image processing circuit.

15. A signal processing system comprising:

an image processing circuit including the device of claim 10 or 11; and

a converter configured to convert an input image signal having an analog value into digital data and output the digital data to the image processing circuit.

11. A device for encoding a moving image using DCT coefficients which are generated by dividing a frame to be processed into a plurality of blocks and performing DCT and quantization with respect to each of the plurality of blocks, the device comprising:

an input image reducer configured to reduce the input image to be encoded, by a factor of n, where n is an integer of one or more, to generate a reduced input image;

a reference image reducer configured to reduce the already encoded reference image by a factor of n to generate a reduced reference image;

a movement amount detector configured to receive the reduced input image and the reduced reference image from the input image reducer and the reference image reducer, and detect a movement amount with respect to each of the plurality of blocks;

a movement amount storage configured to store the movement amounts detected by the movement amount detector;

a still block selector configured to compare the movement amounts stored in the movement amount storage to select S blocks having the smallest movement amounts, where S is an integer of one or more; and

a moving image encoder configured to encode the moving image by forcibly replacing the DCT coefficients with zeros without performing the DCT and the quantization, with respect to the selected S blocks.