Signal processing apparatus and method, program, and storage medium

• US 7,031,536 B2
• Filed: 09/27/2002
• Issued: 04/18/2006
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kajiwara, Hiroshi
• Primary Examiner(s): Johns, Andrew W.
• Assistant Examiner(s): Alavi, Amir
• Application Number:
  US10/255,699
• Publication Number:
  US 20030063811A1
• Time in Patent Office: 1,299 Days
• Field of Search: 382/232, 382/233, 382/238, 382/239, 382/240, 382/246, 382/260, 382/302, 382/305, 375/240.1, 375/240.11, 375/240.19, 375/240.21, 341/50, 341/51, 341/79, 708/300
• US Class Current: 382/240
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

A signal storage processor (101) stores signals input from a signal input unit (100) in a buffer (102) for respective lines. A vertical discrete wavelet transformer (103) reads out an index value L from the signal storage processor (101), and obtains a reference address B from the value L. If L=2, B=2. If L=4, B=0. Furthermore, the vertical discrete wavelet transformer (103) reads out the i-th column of sets of data, which are stored in the buffer (102) and are continuous in the vertical direction (i.e., data read out from four addresses (addresses in the buffer (102)) i×4+B, i×4+mod((B+1),4), i×4+mod((B+2),4), and i×4+mod((B+3),4)), and computes the one-dimensional discrete wavelet transforms of the readout data.

Claims

1. A signal processing apparatus comprising:

storage control means for controlling to store image signals for a predetermined number of lines in predetermined storage means, and counting an index value for each line upon storing an image signal for each line in the storage means;

first wavelet transformation means for specifying addresses in the storage means of data at identical positions in respective lines stored in the storage means using the index value in response to a timing at which the index value reaches a predetermined value, and reading out data stored at the specified addresses, and applying a wavelet transforms to the data in a first direction; and

second wavelet transformation means for applying a wavelet transforms to coefficients obtained by said first wavelet transformation means in a second direction.

2. The apparatus according to claim 1, wherein said storage control means stores image signals for the predetermined number of lines in the storage means for respective lines.

3. The apparatus according to claim 1, wherein said storage control means stores data at identical positions in respective lines of the image signals in the storage means together.

4. The apparatus according to claim 1, wherein the predetermined number of lines is determined in accordance with a size of a filter used by said first and second wavelet transformation means.

5. The apparatus according to claim 4, wherein when the filter used by said first and second wavelet transformation means is a 5×

3 filter, the storage means stores data for four lines as the predetermined number of lines.

6. The apparatus according to claim 4, wherein when the filter used by said first and second wavelet transformation means is a 9×

7 filter, the storage means stores data for six lines as the predetermined number of lines.

7. The apparatus according to claim 1, wherein said first wavelet transformation means specifies addresses in the storage means of data at identical positions in respective lines stored in the storage means using a reference address corresponding to the index value in response to the timing at which the index value reaches the predetermined value.

8. The apparatus according to claim 7, wherein when the storage means stores data for four lines,

when the index value is 2, the reference address is 2, when the index value is 4, the reference address is zero, and the predetermined value is 2.

9. The apparatus according to claim 8, wherein when said first wavelet transformation means reads out i-th data of respective lines of the data of respective lines stored in the storage means, if B represents the reference address, said first wavelet transformation means reads out data stored at four addresses calculated by:

i×

4+B, i×

4+mod((B+1),4), i×

4+mod((B+2),4), and i×

4+mod((B+3),4),

and stores a high-frequency component of coefficients obtained by applying the wavelet transforms to the readout data at the address i×

4+mod((B+3),4) in the storage means.

10. The apparatus according to claim 1, wherein when the storage means stores data for six lines, the predetermined value is one of 2, 4, and 6.

11. The apparatus according to claim 10, wherein when said first wavelet transformation means reads out i-th data of respective lines of the data of respective lines stored in the storage means, if L represents the index value, said first wavelet transformation means reads out data stored at six addresses calculated by:

i×

6+mod(L,6), i×

6+mod ((L+1),6), i×

6+mod((L+2),6), i×

6+mod((L+3),6), i×

6+mod((L+4),6), and i×

6+mod((L+5),6).

12. The apparatus according to claim 1, wherein the first and second directions are respectively vertical and horizontal directions with respect to an image.

13. A signal processing method comprising:

a storage control step of controlling to store image signals for a predetermined number of lines in predetermined storage means, and counting an index value for each line upon storing an image signal for each line in the storage means;

a first wavelet transformation step of specifying addresses in the storage means of data at identical positions in respective lines stored in the storage means using the index value in response to a timing at which the index value reaches a predetermined value, and reading out data stored at the specified addresses, and applying a wavelet transforms to the data in a first direction; and

a second wavelet transformation step of applying a wavelet transforms to coefficients obtained in the first wavelet transformation step in a second direction.

14. A program stored in a computer readable medium for making a computer implement a signal processing method of claim 13.

15. A computer-readable storage medium storing a program of claim 14.

16. A signal processing apparatus for decomposing two-dimensional signals into frequency bands, comprising:

signal input means for inputting two-dimensional signals to be transformed;

first wavelet transformation means for applying a wavelet transforms to the two-dimensional signals input by said signal input means in a first direction to generate coefficients of low- and high-frequency bands;

second wavelet transformation means for applying a wavelet transforms to the coefficients generated by said first wavelet transformation means in a second direction different from the first direction; and

signal storage means for storing two-dimensional signals, or two-dimensional signals and intermediate signals, which are required in transformation in a vertical direction, for a predetermined number of lines,

wherein one of said first and second wavelet transformation means reads out the signals stored in said signal storage means, and applies a wavelet transforms to the signals in the vertical direction, and

said signal storage means independently assigns a memory area to each column sample used in wavelet transformation in the vertical direction.

17. The apparatus according to claim 16, wherein the predetermined number of lines is determined in accordance with a size of a filter used by one of said first and second wavelet transformation means, which is applied in the vertical direction.

18. The apparatus according to claim 16, wherein a size of the memory area assigned to each column sample is determined in accordance with a size of a filter used by one of said first and second wavelet transformation means, which is applied in the vertical direction.

19. The apparatus according to claim 16, wherein a filter used by said first and second wavelet transformation means is a 5×

3 filter, and a size of the memory area assigned to each column sample is not less than four samples.

20. The apparatus according to claim 16, wherein a filter used by said first and second wavelet transformation means is a 9×

7 filter, and a size of the memory area assigned to each column sample is not less than six samples.

21. The apparatus according to claim 16, further comprising filter selection means for selecting a filter used by said first and second wavelet transformation means, and wherein a method of assigning the memory area to each column sample in said signal storage means is changed in accordance with the filter.

22. The apparatus according to claim 21, wherein said filter selection means can select one of 5×

3 and 9×

7 filters.

23. The apparatus according to claim 22, wherein when said signal storage means stores data for four lines, when the index value is zero, the reference address is 2, when the index value is 2, the reference address is zero, and the predetermined value is 2.

24. A signal processing method for decomposing two-dimensional signals into frequency bands, comprising:

a signal input step of inputting two-dimensional signals to be transformed;

a first wavelet transformation step of applying a wavelet transforms to the two-dimensional signals input in the signal input step in a first direction to generate coefficients of low- and high-frequency bands;

a second wavelet transformation step of applying a wavelet transforms to the coefficients generated in the first wavelet transformation step in a second direction different from the first direction; and

a signal storage step of storing two-dimensional signals, or two-dimensional signals and intermediate signals, which are required in transformation in a vertical direction, for a predetermined number of lines,

wherein the signals stored in the signal storage step are read out in one of the first and second wavelet transformation steps, and applied a wavelet transforms in the vertical direction, and

the signal storage step includes a step of independently assigning a memory area to each column sample used in wavelet transformation in the vertical direction.

25. A program stored in a computer readable medium for making a computer implement a signal processing method of claim 24.

26. A computer-readable storage medium storing a program of claim 25.