Image transmitter

• US 20020048322A1
• Filed: 09/18/2001
• Published: 04/25/2002
• Est. Priority Date: 09/19/2000
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamamoto, Akihiro, Mori, Toshiaki, Ibaraki, Susumu
• Granted Patent: US 7,031,386 B2
• Time in Patent Office: Days
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/895 in combination with error concealment
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence

Abstract

There is provided a transmitter which is capable of compressing incoming image with a relatively small delay time and transmitting the compressed image data to a receiver. Image data TD contains at least i pixel values of pixels arranged in line along a single direction, each pixel value being expressed in n bits. A transmitter Tx for compressing such image data and transmitting the image data to a receiver Rx via a transmission path N comprises a blocking section 1, a data compression section 2, and a data sending section 3. The blocking section 1 takes every p pixel values among the i pixel values in the image data to form a data block, and sequentially outputs a plurality of said data blocks DB each including the p pixel values. The data compression section 2 reduces an amount of data from each data block DB outputted from the blocking section 1 and thereby outputs a compressed block CB_r. The data sending section 3 sends the compressed block CB_r outputted from the data compression section 2 onto the transmission path N.

Claims

1. An image transmitter for compressing image data and transmitting the image data to a receiver via a transmission path,

wherein the image data at least contains i pixel values of pixels arranged in line along a single direction, each pixel value being expressed in n bits, the image transmitter comprising:

a blocking section for taking every p pixel values among the i pixel values in the image data to form a data block, and sequentially outputting a plurality of said data blocks each including the p pixel values;

a data compression section for reducing an amount of data from each data block outputted from the blocking section to output a compressed block; and

a data sending section for sending the compressed block outputted from the data compression section onto the transmission path,

wherein i, n, and p are predetermined natural numbers.

2. The image transmitter according to claim 1, wherein:

the compressed block has a fixed length; and

the data sending section at least comprises;

a buffer section for storing the compressed block; and

a sending control section for sending the compressed block stored in the buffer section onto the transmission path.

3. The image transmitter according to claim 1, wherein the data compression section comprises:

a DPCM encoding section for performing a differential pulse code modulation based on two adjoining pixel values in each data block generated by the blocking section to generate and output differential data;

a near-instantaneous compression section for performing a near-instantaneous compression for the differential data outputted from the DPCM encoding section to reduce a number of bits in the differential data, and generating and outputting compressed differential data; and

a packet assembling section for generating and outputting a data packet to the data sending section as the compressed block, the data packet containing a first pixel value in the data block generated by the blocking section and the respective compressed differential data outputted from the near-instantaneous compression section.

4. The image transmitter according to claim 3, wherein the DPCM encoding section comprises:

a delay section for applying a predetermined delay amount to 1^st to (p−

1)^th pixel values in each data block generated by the blocking section, and outputting the resultant pixel values as delayed pixel values; and

a subtraction section for calculating respective differences between 2^nd to p^th pixel values in each data block generated by the blocking section and 1^st to (p−

1)^th delayed pixel values outputted from the delay section to generate (p−

1) said differential data, and outputting the (p−

1) differential data to the near-instantaneous compression section.

5. The image transmitter according to claim 4, wherein the near-instantaneous compression section comprises:

a buffer section for storing the (p−

1) differential data outputted from the DPCM encoding section;

a level determination section for generating a level value based on each of the (p−

1) differential data outputted from the buffer section and outputting the level value, the level value determining a bit to be deleted from each of the (p−

1) differential data; and

a data reduction section f or deleting the bit, as determined by the level value outputted from the level determination section, from each differential data outputted from the buffer section to generate (p−

1) compressed differential data, and outputting the (p−

1) compressed differential data to the packet assembling section.

6. The image transmitter according to claim 5, wherein the level determination section comprises:

a differential data selection section for selecting one of the respective differential data outputted from the buffer section which has a greatest absolute value, and outputting the selected differential data as a maximum differential data; and

a level selection section for selecting one of a predetermined number of said level values based on the maximum differential data outputted from the differential data selection section, and outputting the selected level value to the data reduction section.

7. The image transmitter according to claim 6, wherein:

the data reduction section deletes t bits, as determined by the level value outputted from the level determination section, from each differential data outputted from the buffer section to generate the (p−

1) compressed differential data; and

t is a natural number.

8. The image transmitter according to claim 5, wherein the data packet generated by the packet assembling section contains a first pixel vale in each data block generated by the blocking section, the level value outputted from the level determination section, and the (p−

1) compressed differential data outputted from the data reduction section.

9. The image transmitter according to claim 1, wherein, when it is impossible to take every p pixel values among the i pixel values in the image data to form a data block, the blocking section generates padded data block by using a predetermined padding bit, the padded data block having the same size as that of the data block.

10. The image transmitter according to claim 3, wherein the DPCM encoding section comprises:

a near-instantaneous decompression section for restoring the bits having been deleted from the compressed differential data generated by the near-instantaneous compression section to generate and output decompressed differential data;

a delay section for applying a predetermined delay amount to 1^st to (p−

1)^th pixel values in each data block generated by the blocking section, and outputting the resultant pixel values as delayed pixel values;

an adder section for allowing one of the delayed pixel values which is received first from the delay section to pass through as an added pixel value, and adding 2^nd to (p−

1)^th delayed pixel values outputted from the delay section and 1^st to (p−

2)^th decompressed differential data outputted from the near-instantaneous decompression section, respectively, to generate respective added pixel values; and

a subtraction section for calculating respective differences between 2^nd to p^th pixel values in each block generated by the blocking section and 1^st to (p−

1)^th added pixel values outputted from the adder section to generate (p−

1) said differential data, and outputting the (p−

1) differential data to the near-instantaneous compression section.

11. The image transmitter according to claim 3, wherein the receiver comprises:

a data receiving section for receiving the data packet transmitted via the transmission path and outputting the received data packet;

a packet deassembling section for deassembling the data packet outputted from the data receiving section into the first pixel value in the data block and the respective compressed differential data generated by the near-instantaneous compression section, and outputting the first pixel value in the data block and the respective compressed differential data;

a near-instantaneous decompression section for restoring the bits having been deleted from the compressed differential data generated by the near-instantaneous compression section to generate and output decompressed differential data;

a DPCM decoding section for performing an inverse process of the differential pulse code modulation performed by the DPCM encoding section, generating decoded pixel values from the respective decompressed differential data outputted from the near-instantaneous decompression section, and outputting the decoded pixel values; and

an image data reproduction section for generating reproduced image data from the first pixel value outputted from the packet deassembling section and the respective decoded pixel value outputted from the DPCM decoding section, the reproduced image data representing the image.

12. The image transmitter according to claim 11, wherein:

the data packet has a fixed length; and

the data receiving section comprises;

a buffer section capable of storing at least the data packet of the fixed length; and

a reception control section for outputting the data packet stored in the buffer section to the packet deassembling section.

13. The image transmitter according to claim 11, wherein the receiver further comprises:

a missing block recovery section for, when a data packet is missed by the data receiving section, reproducing pixel values contained in the missing data packet based on the first pixel value from the packet deassembling section and the decoded pixel values from the DPCM decoding section, and outputting the pixel values to the image data reproduction section.

14. The image transmitter according to claim 1, wherein the data compression section comprises:

an orthogonal transform section for multiplying a matrix of j pixel values which are sent from the blocking section as the data block by a predetermined orthogonal transform matrix, and outputting j coefficients; and

a data reduction section for deleting d coefficients representing a predetermined high-frequency component from the j coefficients outputted from the orthogonal transform section to output (j−

d) compressed coefficients, wherein the data sending section sends the (j−

d) compressed coefficients outputted from the data reduction section onto the transmission path as the compressed block.

15. The image transmitter according to claim 14, wherein the data reduction section outputs the (j−

d) compressed coefficients without deleting e coefficients from the j coefficients outputted from the orthogonal transform section, the e coefficients representing a predetermined low-frequency component.

16. The image transmitter according to claim 14, wherein the receiver comprises:

a data receiving section for receiving and outputting the compressed coefficients which are transmitted via the transmission path;

a bit decoding section for performing an inverse process of a process performed by the data reduction section to restore coefficients associated with the high-frequency region based on the compressed coefficients outputted from the data receiving section, and outputting j decompressed coefficients;

an inverse orthogonal transform section for multiplying an inverse matrix of the orthogonal transform matrix by a matrix of the decompressed coefficients outputted from the bit decoding section to generate and output decoded pixel values; and

an image data reproduction section for generating reproduced image data from the respective decoded pixel values outputted from the inverse orthogonal transform section, the reproduced image data representing the image.

17. The image transmitter according to claim 16, wherein:

the set of (j−

d) compressed coefficients have a fixed length; and

the data receiving section comprises;

a buffer section capable of storing at least the set of (j−

d) compressed coefficients; and

a reception control section for outputting the (j−

d) compressed coefficients stored in the buffer section to the bit decoding section.

18. The image transmitter according to claim 16, wherein the receiver further comprises:

a missing block recovery section for, when the data receiving section misses a set of compressed coefficients, reproducing the set of missing compressed coefficients based on the decoded pixel values outputted from the inverse orthogonal transform section, and outputting the reproduced set of missing compressed coefficients to the image data reproduction section.

19. A driving assistant system for assisting in the driving of a vehicle, the system comprising:

a transmission path;

a plurality of image capturing devices each of which is fixed on the vehicle and which captures an image of surroundings of the vehicle and outputs captured image data;

a plurality of image processing sections each of which is provided following the image capturing device and which performs a clipping process for the captured image data outputted from the respective preceding image capturing device to generate partial image data, wherein each partial image data at least contains i pixel values of pixels arranged in line along a single direction, each pixel value being expressed in n bits; and

a plurality of transmitters each of which is provided following an associated one of the plurality of image processing sections,

wherein each transmitter comprises;

a blocking section for taking every p pixel values among the i pixel values in the partial image data from the associated image processing section to form a data block, and sequentially outputting a plurality of said data blocks each including the p pixel values;

a data compression section for reducing an amount of data from each data block outputted from the blocking section to output a compressed block; and

a data sending section for sending the compressed block outputted from the data compression section onto the transmission path,

wherein the system further comprises;

a receiver for receiving and decompressing each compressed block from the transmission path, restoring each data block, and reproducing the respective partial image data;

an image synthesis section for performing a synthesis process for the partial image data from the receiver and outputting merged image data, the merged image data representing an image in which images represented by the respective partial image data are synthesized; and

a display section for displaying the image represented by the merged image data outputted from the image synthesis section,

wherein i, n, and p are predetermined natural numbers.

20. A remote control system for exerting an action on an object via remote control, the system comprising:

a transmission path;

an image capturing device which is provided in a neighborhood of the object and which captures an image of surroundings of the object and outputs captured image data, wherein the captured image data at least contains i pixel values of pixels arranged in line along a single direction, each pixel value being expressed in n bits; and

a transmitter

wherein the transmitter comprises;

a blocking section f or taking every p pixel values among the i pixel values in the captured image data from the image capturing device to form a data block, and sequentially outputting a plurality of said data blocks each including the p pixel values;

a data compression section for reducing an amount of data from each data block outputted from the blocking section to output a compressed block; and

a data sending section for sending the compressed block outputted from the data compression section onto the transmission path,

wherein the system further comprises;

a receiver for receiving and decompressing each compressed block from the transmission path, restoring each data block, and reproducing the captured image data;

a display section for displaying the image represented by the captured image data outputted from the receiver for viewing by an operator;

a control data generation section for generating and outputting control data for exerting an action on the object in accordance with control made by the operator; and

a control data sending section for sending control data from the control data generation section onto the transmission path;

a control data receiving section for receiving and outputting the control data from the transmission path; and

a manipulator section for exerting the action on the object in accordance with the control data received from the control data receiving section,

wherein i, n, and p are predetermined natural numbers.

21. An image compression method for incorporation in a transmitter for compressing image data and transmitting the image data to a receiver via a transmission path,

wherein the image data at least contains i pixel values of pixels arranged in line along a single direction, each pixel value being expressed in n bits, the method comprising:

a blocking step of taking every p pixel values among the i pixel values in the image data to form a data block, and sequentially outputting a plurality of said data blocks each including the p pixel values;

a data compression step of reducing an amount of data from each data block outputted in the blocking step to output a compressed block; and

a data sending step of sending the compressed block outputted in the data compression step onto the transmission path,

wherein i, n, and p are predetermined natural numbers.

22. The image compression according to claim 21,

wherein the data compression step comprises:

a DPCM encoding step of performing a differential pulse code modulation based on two adjoining pixel values in each data block generated by the blocking step to generate differential data;

a near-instantaneous compression step of performing a near-instantaneous compression for the differential data generated by the DPCM encoding step to reduce a number of bits in the differential data and generating, and outputting compressed differential data; and

a packet assembling step of generating a data packet as the compressed block, the data packet containing a first pixel value in the data block generated by the blocking step and the respective compressed differential data generated by the near-instantaneous compression step.

23. The image compression according to claim 21,

wherein the data compression step comprises:

an orthogonal transform step of multiplying a matrix of j pixel values which are generated by the blocking step as the data block by a predetermined orthogonal transform matrix, and outputting j coefficients; and

a bit reduction step of deleting d coefficients representing a predetermined high-frequency component from the j coefficients outputted in the orthogonal transform step to output (j−

d) compressed coefficients as the compressed block.