Method and apparatus for implementing digital filters

• US 20060212502A1
• Filed: 12/30/2004
• Published: 09/21/2006
• Est. Priority Date: 12/30/2004
• Status: Abandoned Application

• Current Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Chatterjee, Chanchal
• Application Number:
  US11/027,207
• Publication Number:
  US 20060212502A1
• Time in Patent Office: Days
• US Class Current: 708/300
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: H03H 17/026 Averaging filters
• CPC Class Codes: H03H 17/06 Non-recursive filters
• CPC Class Codes: H03H 2017/0298 DSP implementation

Abstract

In one embodiment, the present invention discloses an apparatus and method for providing efficient implementations of Finite Impulse Response (FIR) digital filters. Specifically, a result from a FIR digital filter can be efficiently computed by using an AVG operation or instruction in conjunction with one or more other operations. The unique use of the AVG operation will allow FIR filters of various types, e.g., Types 1-4, to significantly reduce computational cycles.

Claims

1. A method for processing an image signal, comprising:

providing at least one Finite Impulse Response (FIR) filter, wherein said at least one FIR filter comprises at least one of said functions;

(A₁+A₂+c*ONE)>

>

1, where cε

{−

2,−

1,0,1,2},

(A₁+A₂+A₃+A₄+c*ONE)>

>

2, where cε

{0,1,2},

(A₁+A₂+A₃+A₄+A₅+A₆+A₇+A₈+c*ONE)>

>

3, where cε

{0,1,2,3,4}.

(A₁+A₂+A₃+A₄+ . . . +A₁₅+A₁₆+c*ONE)>

>

4, where cε

{0,1,2, . . . , 8},

where each of said A₁-A₁₆ represents a vector, where ONE represents a packed vector;

where >

>

represents a bitwise logical right shift; and

applying said at least one FIR filter to process the image signal, where a result of said at least one FIR filter is computed using at least an AVG operation.

2. The method of claim 1, wherein said AVG operation is expressed as:

AVG(A,B)=[(a_i+b_i)>

>

1 for i=1, . . . ,8], where a_i and b_i represent data values, where A represents a vector and where B represents a vector.

3. The method of claim 1, wherein said ONE is expressed as:

ONE=[0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01],

where 0x01 is a byte containing 1 in its least significant bit and 0s elsewhere.

4. The method of claim 1, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(B₁,B₂)−

(B₁{circumflex over (0)}B₂)|((A₁e,cir 0A₂) &

(A₃{circumflex over (0)}A₄)) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

5. The method of claim 1, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(B₁,B₂)+(B₁{circumflex over (0)}B₂) &

((A₁{circumflex over (0)}A₂)|(A₃{circumflex over (0)}A₄)) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

6. The method of claim 1, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(B₁,B₂)+(B₁{circumflex over (0)}B₂) &

(A₁{circumflex over (0)}A₂) &

(A₃{circumflex over (0)}A₄) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

7. The method of claim 1, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(A₁,B₂)+(A₁{circumflex over (0)}B₂) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

8. The method of claim 1, wherein said result, R, of said at least one FIR filter is computed as:

R=SUBSAT(U−

E),

where U=ADDSAT(D+2*ONE), where 2*ONE is a constant, where D=AVG(AVG(AVG(A₁,A₂),AVG(A₃,A₄)), AVG(AVG(A₅,A₆), AVG(A₇,A₈))), where E=SUBSAT(U−

L) &

7*ONE, where 7*ONE is a constant, where L=(A₁+A₂+A₃+A₄+A₅+A₆+A₇+A₈+c*ONE)>

>

3, where c*ONE is a constant, and where SUBSAT(A,B)=[CLIP(a_i−

b_i) for i=1, . . . ,8], where ADDSAT(A,B)=[CLIP(a_i+b_i) for i=1, . . . ,8], and where CLIP (x) clips x to range [0,255].

9. A computer-readable carrier having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps of a method for processing an image signal, comprising of:

providing at least one Finite Impulse Response (FIR) filter, wherein said at least one FIR filter comprises at least one of said functions;

(A₁+A₂+c*ONE)>

>

1, where cε

{−

2,−

1,0,1,2},

(A₁+A₂+A₃+A₄+c*ONE)>

>

2, where cε

{0,1,2},

(A₁+A₂+A₃+A₄+A₅+A₆+A₇+A₈+c*ONE)>

>

3, where cε

{0,1,2,3,4},

(A₁+A₂+A₃+A₄+ . . . +A₁₅+A₁₆+C*ONE)>

>

4, where cε

{0,1,2, . . . , 8},

where each of said A₁-A₁₆ represents a vector, where ONE represents a packed vector;

where >

>

represents a bitwise logical right shift; and

applying said at least one FIR filter to process the image signal, where a result of said at least one FIR filter is computed using at least an AVG operation.

10. The computer-readable carrier of claim 9, wherein said AVG operation is expressed as:

AVG(A,B)=[(a_i+b_i)>

>

1 for i=1, . . . ,8], where a_i and b_i represent data values, where A represents a vector and where B represents a vector.

11. The computer-readable carrier of claim 9, wherein said ONE is expressed as:

ONE=[0 x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01],

where 0x01 is a byte containing 1 in its least significant bit and 0s elsewhere.

12. The computer-readable carrier of claim 9, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(B₁,B₂)−

(B₁{circumflex over (0)}B₂)|((A₁{circumflex over (0)}A₂) &

(A₃{circumflex over (0)}A₄)) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

13. The computer-readable carrier of claim 9, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(B₁,B₂)+(B₁{circumflex over (0)}B₂) &

((A₁{circumflex over (0)}A₂)|(A₃{circumflex over (0)}A₄)) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

14. The computer-readable carrier of claim 9, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(B₁,B₂)+(B₁{circumflex over (0)}B₂) &

(A₁{circumflex over (0)}A₂) &

(A₃{circumflex over (0)}A₄) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

15. The computer-readable carrier of claim 9, wherein said result, R, of said at least one FIR filter is computed as:

R=AVG(A₁,B₂)+(A₁{circumflex over (0)}B₂) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.

16. The computer-readable carrier of claim 9, wherein said result, R, of said at least one FIR filter is computed as:

R=SUBSAT(U−

E),

where U=ADDSAT(D+2*ONE), where 2*ONE is a constant, where D=AVG(AVG(AVG(A₁,A₂), AVG(A₃,A₄)), AVG(AVG(A₅,A₆), AVG(A₇,A₈))), where E=SUBSAT(U−

L) &

7*ONE, where 7*ONE is a constant, where L=(A₁+A₂+A₃+A₄+A₅+A₆+A₇+A₈+c*ONE)>

>

3, where c*ONE is a constant, and where SUBSAT(A,B)=[CLIP(a_i−

b_i) for i=1, . . . ,8], where ADDSAT(A,B)=[CLIP(a_i+b_i) for i=1, . . . ,8], and where CLIP (x) clips x to range [0,255].

17. An apparatus for processing an image signal, comprising:

means for providing at least one Finite Impulse Response (FIR) filter, wherein said at least one FIR filter comprises at least one of said functions;

(A₁+A₂+c*ONE)>

>

1, where cε

{−

2,−

1,0,1,2},

(A₁+A₂+A₃+A₄+c*ONE)>

>

2, where cε

{0,1,2},

(A₁+A₂+A₃+A₄+A₅+A₆+A₇+A₈+c*ONE)>

>

3, where cε

{0,1,2,3,4},

(A₁+A₂+A₃+A₄+ . . . +A₁₅+A₁₆+c*ONE)>

>

4, where cε

{0,1,2, . . . , 8},

where each of said A₁-A₁₆ represents a vector, where ONE represents a packed vector;

where >

>

represents a bitwise logical right shift; and

means for applying said at least one FIR filter to process the image signal, where a result of said at least one FIR filter is computed using at least an AVG operation.

18. The apparatus of claim 17, wherein said AVG operation is expressed as:

AVG(A,B)=[(a_i+b_i)>

>

1 for i=1, . . . ,8], where a_i and b_i represent data values, where A represents a vector and where B represents a vector.

19. The apparatus of claim 17, wherein said ONE is expressed as:

ONE=[0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01],

where 0x01 is a byte containing 1 in its least significant bit and 0s elsewhere.

20. The apparatus of claim 17, wherein said result, R, of said at least one FIR filter is computed as at least one of:

R=AVG(B₁,B₂)−

(B₁{circumflex over (0)}B₂)|((A₁{circumflex over (0)}A₂) &

(A₃{circumflex over (0)}A₄)) &

ONE,
R=AVG(B₁,B₂)+(B₁{circumflex over (0)}B₂) &

((A₁{circumflex over (0)}A₂)|(A₃{circumflex over (0)}A₄)) &

ONE,
R=AVG(B₁,B₂)+(B₁{circumflex over (0)}B₂) &

(A₁{circumflex over (0)}A₂) &

(A₃{circumflex over (0)}A₄) &

ONE,
R=AVG(A₁,B₂)+(A₁{circumflex over (0)}B₂) &

ONE,

where {circumflex over (0)} represents bitwise exclusive OR, where | represents bitwise OR, and &

represents bitwise AND.