Image coding apparatus and image decoding apparatus

• US 6,381,275 B1
• Filed: 12/04/1996
• Issued: 04/30/2002
• Est. Priority Date: 06/28/1996
• Status: Expired

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Asai, Kohtaro, Sekiguchi, Shunichi, Murakami, Tokumichi, Fukuhara, Takahiro
• Primary Examiner(s): LEE, Y YOUNG
• Application Number:
  US08/759,834
• Time in Patent Office: 1,973 Days
• Field of Search: H04/N.712, H04/N.718, 348/407, 348/402, 348/409, 348/411-416, 348/699, 375/240.06, 375/240.14
• US Class Current: 375/240.06
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 19/23 with coding of regions that are present throughout a whole video segment, e.g. sprites, background or mosaic
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• 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
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

An image coding apparatus which includes a frame memory selecting unit (35) for selecting, in response to a selection signal, an image to be continuously stored in a plurality of frame memories (9, 10) as a background image and storing the background image into the plurality of frame memories (9, 10), and a background motion compensating unit (14, 39) for performing motion compensating prediction corresponding to an input image based on the background image to generate a predicted image based on the motion compensating prediction, and an image decoding apparatus corresponding to the image coding apparatus.

Claims

1. An image coding apparatus, comprising:

frame memories for storing a plurality of decoded images;

motion compensating prediction means for performing motion compensating prediction corresponding to an input image based on the plurality of decoded images stored in said frame memories to produce a motion vector and for generating a predicted image based on the motion compensating prediction;

prediction error calculation means for calculating a difference between the predicted image generated by said motion compensating prediction means and the input image to calculate a prediction error image;

decoding means for generating the decoded images from the prediction error image calculated by said prediction error calculation means and the predicted image;

image storage controller for determining and outputting the coding mode of the image to be predicted according to an input control signal, and allocating the type of the reference image to be stored in one of said frame memories to continuously decoded image or the stationary background image based on the selected coding mode of the image to be predicted; and

background motion compensation means for performing motion compensating prediction corresponding to the input image based on the background image to generate a motion vector and generating a predicted image based on the motion compensating prediction, wherein said image storage controller performs re-writing of image contents into said frame memories in response to a given control signal.

2. An image coding apparatus according to claim 1, wherein said frame memories includes a frame memory for storing a decoded image, and another frame memory for storing the background image.

3. An image coding apparatus according to claim 1, wherein re-writing of image contents into said storage means by said background image storage control means is performed in units of a picture after a predetermined interval of time or in response to a control signal from the outside.

4. An image coding apparatus according to claim 1, wherein re-writing of image contents into said storage means by said background image storage control means is performed in units of a macroblock after a predetermined interval of time or in response to a control signal from the outside.

5. An image coding apparatus according to claim 1, wherein said background motion compensation means has a variable searching range for a motion vector from the background images.

6. An image coding apparatus according to claim 1, further comprising differential vector generation means for holding a motion vector obtained from said motion compensation means or said background motion compensation means and calculating a difference vector between the generated motion vector and the motion vector in the past, and the difference vector is variable length coded.

7. An image coding apparatus according to claim 1, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a picture after a predetermined time-interval.

8. An image coding apparatus according to claim 1, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a macro-block after a predetermined time-interval.

9. An image coding apparatus according to claim 1, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a picture in response to an outside control signal.

10. An image coding apparatus according to claim 1, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a macro-block in response to an outside control signal.

11. An image decoding apparatus, comprising:

frame memories for storing a plurality of decoded images;

motion compensation means for performing motion compensating prediction based on the decoded images stored in said frame memories to generate a motion compensated image;

decoding means for generating coded images from the motion compensated image from said motion compensation means and a prediction error image;

an image storage controller for allocating the type of the reference image to be stored in one of said frame memories to continuously decoded image or the stationary background image based on the coding mode of the image to be decoded, which is extracted from encoded bitstream; and

background predicted image generation means for generating a background predicted image based on the background image, wherein said image storage controller performs re-writing of image contents into said frame memories in response to a given control signal.

12. An image decoding apparatus according to claim 11, wherein said frame memories includes a frame memory for storing a decoded image, and another frame memory for storing the background image.

13. An image decoding apparatus according to claim 11, wherein re-writing of image contents into said storage means by said background image storage control means is performed in units of a picture after a predetermined interval of time or in response to a control signal from the outside.

14. An image decoding apparatus according to claim 11, wherein re-writing of image contents into said storage means by said background image storage control means is performed in units of a macroblock after a predetermined interval of time or in response to a control signal from the outside.

15. An image decoding apparatus according to claim 11, further comprising a motion vector adding unit for holding a motion vector decoded in the past and adding the motion vector decoded in the past to a difference vector to regenerate a motion vector.

16. An image coding apparatus according to claim 11, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a picture after a predetermined time-interval.

17. An image coding apparatus according to claim 11, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a macro-block after a predetermined time-interval.

18. An image coding apparatus according to claim 11, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a picture in response to an outside control signal.

19. An image coding apparatus according to claim 11, wherein said background image storage control means performs re-writing of image contents into said storage means per unit of a macro-block in response to an outside control signal.

20. An image coding/decoding apparatus, comprising:

an image coding apparatus, including,

image coding frame memories for storing a plurality of decoded images;

image coding motion compensating prediction means for performing motion compensating prediction corresponding to an input image based on the plurality of decoded images stored in said image coding frame memories to produce a motion vector and for generating a predicted image based on the motion compensating prediction;

image coding prediction error calculation means for calculating a difference between the predicted image generated by said image coding motion compensating prediction means and the input image to calculate a prediction error image;

first decoding means for generating the decoded images from the prediction error image calculated by said image coding prediction error calculation means and the predicted image;

an image coding image storage controller for determining and outputting the coding mode of the image to be predicted according to an input control signal, and allocating the type of the reference image to be stored in one of said image coding frame memories to continuously decoded image or the stationary background image based on the selected coding mode of the image to be predicted; and

image coding background motion compensation means for performing motion compensating prediction corresponding to the input image based on the background image to generate a motion vector and generating a predicted image based on the motion compensating prediction; and

an image decoding apparatus, including,

image decoding frame memories for storing a plurality of decoded images;

image decoding motion compensation means for performing motion compensating prediction based on the decoded images stored in said image decoding frame memories to generate a motion compensated image;

second decoding means for generating coded images from the motion compensated image from said image decoding motion compensation means and a prediction error image;

an image decoding image storage controller for allocating the type of the reference image to be stored in one of said image decoding frame memories to continuously decoded image or the stationary background image based on the coding mode of the image to be decoded, which is extracted from encoded bitstream; and

image decoding background predicted image generation means for generating a background predicted image based on the background image,

wherein said image decoding image storage controller performs re-writing of image contents into said image decoding frame memories in response to a given control signal.