Image processing apparatus and method

• US 5,903,669 A
• Filed: 01/25/1996
• Issued: 05/11/1999
• Est. Priority Date: 01/31/1995
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Hirabayashi, Yasuji
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US08/591,154
• Time in Patent Office: 1,202 Days
• Field of Search: 348/395, 348/398, 348/400, 348/403, 348/412, 348/415, 348/420, 348/421, 358/432, 358/433, 382/232, 382/236, 382/238, 382/239, 382/240, 382/246, 382/248, 382/250
• US Class Current: 382/232
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

In compressing an image in units of blocks, the image is compressed in accordance with the size of a redundant portion of the image to increase the compression factor of the image data. An image compression apparatus for encoding an image in units of blocks includes a size discrimination unit for discriminating a block image size suitable for encoding and compressing a predetermined image area, a generation unit for dividing the image area to generate a plurality of block images having different sizes on the basis of the discrimination result of the size discrimination unit, and a compression unit for compressing each block image data representing a block image and generated from the generation unit, on the basis of the size of the block image data.

Claims

1. An image compression apparatus for encoding an image in units of blocks, comprising:

size discrimination means for discriminating a block image size suitable for encoding and compressing a predetermined image area of the image, by comparing an encoding amount obtained by encoding the predetermined image area in units of a block of a first size and an encoding amount obtained by encoding the same predetermined image area in units of a block of a second size different from the first size;

generation means for dividing the image area to generate a plurality of block images having different sizes based on a discrimination result of said size discrimination means; and

compression means for compressing each block of image data representing a block image generated by said generation means, based on a size of the block of image data.

2. An apparatus according to claim 1, wherein the predetermined image area is a block of n×

n pixels (where n is an integer).

3. An apparatus according to claim 1, wherein the predetermined image area is a total area of one frame.

4. An apparatus according to claim 1, wherein said compression means performs compression together with DCT transform of the block image data.

5. An apparatus according to claim 4, wherein said compression means performs compression by quantizing a DCT coefficient generated in the DCT transform.

6. An apparatus according to claim 1, wherein said compression means performs compression by differential coding for generating difference value data in units of pixels in the block and encoding the difference value data.

7. An image compression method of encoding an image in units of blocks, comprising:

a size discrimination step of discriminating a block image size suitable for encoding and compressing a predetermined image area of the image, by comparing an encoding amount obtained by encoding the predetermined image area in units of a block of a first size and an encoding amount obtained by encoding the same predetermined image area in units of a block of a second size different from the first size;

a generation step of dividing the image area to generate a plurality of block images having different sizes based on a discrimination result in said size discrimination step; and

a compression step of compressing each block of image data representing a block image generated in said generation step, based on a size of the block of image data.

8. An image processing apparatus comprising:

data generation means for reading an image and generating image data;

size discrimination means for discriminating a block image size suitable for encoding and compressing an image area of at least part on an image represented by the image data, by comparing an encoding amount obtained by encoding the image area in units of a block of a first size and an encoding amount obtained by encoding the same image area in units of a block of a second size different from the first size;

generation means for dividing the image area to generate a plurality of block images having different sizes based on a discrimination result of said size discrimination means; and

compression means for compressing each block of image data representing a block image generated by said generation means, based on a size of the block of image data.

9. An apparatus according to claim 9, wherein said generation means and said compression means respectively perform generation and compression in accordance with a read speed of said data generation means.

10. An image processing method comprising:

a data generation step of reading an image and generating image data;

a size discrimination step of discriminating a block image size suitable for encoding and compressing an image area of at least part on an image represented by the image data, by comparing an encoding amount obtained by encoding the image area in units of a block of a first size and an encoding amount obtained by encoding the same image area in units of a block of a second size different from the first size;

a generation step of dividing the image area to generate a plurality of block images having different sizes based on a discrimination result in said size discrimination step; and

a compression step of compressing each block of image data representing a block image generated in said generation step, based on a size of the block of image data.

11. An image processing apparatus comprising:

storage means for storing image data of at least one frame;

size discrimination means for discriminating a block image size suitable for encoding and compressing an image area of at least part on an image represented by the image data, by comparing an encoding amount obtained by encoding the image area in units of a block of a first size and an encoding amount obtained by encoding the same image area in units of a block of a second size different from the first size;

generation means for dividing the image area to generate a plurality of block images having different sizes based on a discrimination result of said size discrimination means; and

compression means for compressing each block of image data representing a block image generated by said generation means, based on a size of the block of image data.

12. An image processing method comprising:

a storage step of storing image data of at least one frame;

a size discrimination step of discriminating a block image size suitable for encoding and compressing an image area of at least part on an image represented by the image data, by comparing an encoding amount obtained by encoding the image area in units of a block of a first size and an encoding amount obtained by encoding the same image area in units of a block of a second size different from the first size;

a generation step of dividing the image area to generate a plurality of block images having different sizes based on a discrimination result in said size discrimination step; and

a compression step of compressing each block of image data representing a block image generated in said generation step, based on a size of the block of image data.

13. An image processing apparatus comprising:

size discrimination means for discriminating a block image size suitable for encoding and compressing a predetermined image area of an image, by comparing an encoding amount obtained by encoding the predetermined image area in units of a block of a first size and an encoding amount obtained by encoding the same predetermined image area in units of a block of a second size different from the first size;

generation means for dividing the image area to generate a plurality of block images having different sizes based on a discrimination result of said size discrimination means;

compression means for compressing each block of image data representing a block image generated by said generation means, based on a size of the block of image data; and

communication control means for controlling communication to sent the block of image data compressed by said compression means to another equipment.

14. An apparatus according to claim 13, wherein said communication control means performs communication of the block image data simultaneously with compression by said compression means.

15. An apparatus according to claim 13, wherein said communication control means starts communication of the block image data after compression by said compression means.

16. An image processing method comprising:

a size discrimination step of discriminating a block image size suitable for encoding and compressing a predetermined image area of an image, by comparing an encoding amount obtained by encoding the predetermined image area in units of a block of a first size and an encoding amount obtained by encoding the same predetermined image area in units of a block of a second size different from the first size;

a generation step of dividing the image area to generate a plurality of block images having different sizes based on a discrimination result in said size discrimination step;

a compression step of compressing each block of image data representing a block image generated in said generation means, based on a size of the block of image data; and

a communication control step of controlling communication to sent the block of image data compressed in said compression step to another equipment.

17. An image processing apparatus comprising:

size discrimination means for discriminating a block image size suitable for encoding and compressing a predetermined image area of an image, by comparing an encoding amount obtained by encoding the predetermined image area in units of a block of a first size and an encoding amount obtained by encoding the same predetermined image area in units of a block of a second size different from the first size;

generation means for dividing the image area to generate a plurality of block images having different sizes based on a discrimination result of said size discrimination means;

compression means for compressing each block of image data representing a block image generated by said generation means, based on a size of the block of image data; and

storage means for storing a plurality of frames of the blocks of image data compressed by said compression means in a predetermined storage unit.

18. An image processing method comprising:

a size discrimination step of discriminating a block image size suitable for encoding and compressing a predetermined image area of an image, by comparing an encoding amount obtained by encoding the predetermined image area in units of a block of a first size and an encoding amount obtained by encoding the same predetermined image area in units of a block of a second size different from the first size;

a generation step of dividing the image area to generate a plurality of block images having different sizes based on a discrimination result in said size discrimination step;

a compression step of compressing each block of image data representing a block image generated in said generation means, based on a size of the block of image data; and

a storage step of storing a plurality of frames of the blocks of image data compressed said compression step in a predetermined storage unit.