Scaled forward and inverse discrete cosine transform and video compression/decompression systems employing the same

• US 6,134,270 A
• Filed: 06/13/1997
• Issued: 10/17/2000
• Est. Priority Date: 06/13/1997
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Mou, Alex Z.
• Primary Examiner(s): Kelley, Chris S.
• Assistant Examiner(s): VO, TUNG T
• Application Number:
  US08/874,382
• Time in Patent Office: 1,222 Days
• Field of Search: 348/403, 348/404, 348/405, 348/406, 348/407, 348/410, 348/413, 348/415, 348/416, 348/699, 348/725.03, 364/725, 382/241, 382/232
• US Class Current: 375/240.21
• CPC Class Codes: G06F 17/147 Discrete orthonormal transforms, e.g. discrete cosine transform, discrete sine transform, and variations therefrom, e.g. modified discrete cosine transform, integer transforms approximating the discrete cosine transform G06F17/145 takes precedence
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

A system and method of a forward and/or inverse discrete cosine transform in a video system. In one embodiment, an array of DCT transform coefficients are converted to a two dimensional array of spatial data. The array of DCT transform coefficients are first operated upon by a pre-scale computation unit (implemented in either hardware or software) which multiplies a set of predetermined pre-scale constants with the input coefficients. The pre-scale constants multiplied by the input DCT coefficient matrix form a symmetric pre-scale array. Upon pre-scaling using the symmetric pre-scale factor array, an intermediary array is composed by performing intermediary calculations upon each column vector of the pre-scaled array. The output of this intermediary calculation is composed to form an intermediary array. Subsequently, a set of calculations are performed row-wise upon each row vector of the intermediary array to thereby form the output array of spatial data. In one implementation, the array of pre-scale coefficients (i.e., the symetric pre-scale factor array) may be represented as the result of a matrix multiplication M×U×M, where the array U consists of a set of coefficients all equal to 1, and wherein the array M is an array of coefficients wherein the equal row-column diagonal of coefficients include a set of pre-scale constants and all other coefficients in the array are equal to 0. The pre-scale constants includes a set of constants expressed by the cos(π/16), where n=1, 2, 3 and 4. In another embodiment, the calculations are reversed to perform a forward discrete cosine transform operation.

Claims

1. A method for performing an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image in a video system comprising:

multiplying said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

performing an intermediary calculation column-wise upon said pre-scaled array to obtain an intermediary array; and

performing a final calculation row-wise upon said intermediary array;

wherein said symmetric pre-scale factor array is an array expressible by the product M×

U×

M, where U is a matrix of coefficients each being equal to 1 and M is an array wherein a set of pre-scale constants are expressed along its diagonal and wherein all other coefficients are 0; and

creating a video bitstream representative of said video image using results from said final calculation.

2. The method for performing an inverse discrete cosine transform as recited in claim 1 further comprising retrieving each DCT coefficient of said matrix of DCT coefficients from a memory.

3. The method for performing an inverse discrete cosine transform as recited in claim 1 wherein said performing said intermediary calculation includes:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said pre-scaled array.

4. The method for performing an inverse discrete cosine transform as recited in claim 3 wherein said performing said final calculation includes:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

1/16)-b7;

v1=b1+b7tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1](b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1)

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said intermediary array.

5. The method for performing an inverse discrete cosine transform as recited in claim 1 wherein said set of pre-scale constants comprise the constants cos(nπ

/16), where n=1, 2, 3, 4.

6. A method for performing an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image in a video system comprising:

multiplying said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

performing an intermediary calculation row-wise upon said pre-scaled array to obtain an intermediary array;

performing a final calculation column-wise upon said intermediary array;

wherein said symmetric pre-scale factor array is an array expressible by the product M×

U×

M, where U is a matrix of coefficients each being equal to 1 and M is an array wherein a set of pre-scale constants are expressed along its diagonal and wherein all other coefficients are 0; and

creating a video bitstream representative of said video image using results from said final calculation.

7. The method for performing an inverse discrete cosine transform as recited in claim 6 further comprising retrieving each DCT coefficient of said matrix of DCT coefficients from a memory.

8. The method for performing an inverse discrete cosine transform as recited in claim 6 wherein said performing said intermediary calculation includes:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said pre-scaled array.

9. The method for performing an inverse discrete cosine transform as recited in claim 8 wherein said performing said final calculation includes:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said intermediary array.

10. The method for performing an inverse discrete cosine transform as recited in claim 6 wherein said set of pre-scale constants comprise the constants cos(nπ

/16), where n=1, 2, 3, 4.

11. An inverse discrete cosine transform calculation unit for a video system configured to perform an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image, said inverse discrete cosine transform calculation unit comprising:

a prescale computation unit configured to multiply said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

a column vector computation unit configured to perform an intermediary calculation column-wise upon said pre-scaled array to obtain an intermediary array; and

a row vector computation unit configured to perform a final calculation row-wise upon said intermediary array to provide data representative of said video image;

wherein said symmetric pre-scale factor array is an array which may be expressed by the product M×

U×

M, where U is a matrix of coefficients each being equal to 1 and M is an array wherein a set of pre-scale constants are expressed along its diagonal and wherein all other coefficients are 0.

12. The inverse discrete cosine transform calculation unit as recited in claim 11 further comprising a memory for storing each DCT coefficient of said matrix of DCT coefficients.

13. The inverse discrete cosine transform calculation unit as recited in claim 11 wherein said column vector computation unit is configured to calculate:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said pre-scaled array.

14. The inverse discrete cosine transform calculation unit as recited in claim 13 wherein said row vector computation unit is configured to calculate:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said intermediary array.

15. The inverse discrete cosine transform calculation unit as recited in claim 11 wherein said set of pre-scale constants comprise the constants cos(nπ

/16), where n=1, 2, 3, 4.

16. An inverse discrete cosine transform calculation unit for a video system configured to perform an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image, said inverse discrete cosine transform calculation unit comprising:

a prescale computation unit configured to multiply said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

a row vector computation unit configured to perform an intermediary calculation row-wise upon said pre-scaled array to obtain an intermediary array; and

a column vector computation unit configured to perform a final calculation column-wise upon said intermediary array to provide data representative of said video image;

wherein said symmetric pre-scale factor array is an array which may be expressed by the product M×

U×

M, where U is a matrix of coefficients each being equal to 1 and M is an array wherein a set of pre-scale constants are expressed along its diagonal and wherein all other coefficients are 0.

17. The inverse discrete cosine transform calculation unit as recited in claim 16 further comprising a memory for storing each DCT coefficient of said matrix of DCT coefficients.

18. The inverse discrete cosine transform calculation unit as recited in claim 16 wherein said row vector computation unit is configured to calculate:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said pre-scaled array.

19. The inverse discrete cosine transform calculation unit as recited in claim 18 wherein said column vector computation unit is configured to calculate:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said intermediary array.

20. The inverse discrete cosine transform calculation unit as recited in claim 16 wherein said set of pre-scale constants comprise the constants cos(nπ

/16), where n=1, 2, 3, 4.

21. A method for performing an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image in a video system comprising:

multiplying said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

performing an intermediary calculation column-wise upon said pre-scaled array to obtain an intermediary array;

performing a final calculation row-wise upon said intermediary array;

wherein said performing said intermediary calculation includes;

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said pre-scaled array; and

creating a video bitstream representative of said video image using results from said final calculation.

22. The method for performing an inverse discrete cosine transform as recited in claim 21 further comprising retrieving each DCT coefficient of said matrix of DCT coefficients from a memory.

23. The method for performing an inverse discrete cosine transform as recited in claim 21 wherein said performing said final calculation includes:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said intermediary array.

24. A method for performing an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients [to thereby construct] associated with a video image in a video system comprising:

multiplying said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

performing an intermediary calculation row-wise upon said pre-scaled array to obtain an intermediary array; and

performing a final calculation column-wise upon said intermediary array;

wherein said performing said intermediary calculation includes;

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said prescaled array; and

creating a video bitstream representative of said video image using results from said final calculation.

25. The method for performing an inverse discrete cosine transform as recited in claim 24 further comprising retrieving each DCT coefficient of said matrix of DCT coefficients from a memory.

26. The method for performing an inverse discrete cosine transform as recited in claim 24 wherein said performing said final calculation includes:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said intermediary array.

27. An inverse discrete cosine transform calculation unit for a video system configured to perform an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image, said inverse discrete cosine transform calculation unit comprising:

a prescale computation unit configured to multiply said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

a column vector computation unit configured to perform an intermediary calculation column-wise upon said pre-scaled array to obtain an intermediary array; and

a row vector computation unit configured to perform a final calculation row-wise upon said intermediary array to provide data representative of said video image;

wherein said column vector computation unit is configured to calculate;

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said pre-scaled array.

28. The inverse discrete cosine transform calculation unit as recited in claim 27 further comprising a memory for storing each DCT coefficient of said matrix of DCT coefficients.

29. The inverse discrete cosine transform calculation unit as recited in claim 27 wherein said row vector computation unit is configured to calculate:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said intermediary array.

30. An inverse discrete cosine transform calculation unit for a video system configured to perform an inverse discrete cosine transform (IDCT) upon a matrix of DCT coefficients associated with a video image, said inverse discrete cosine transform calculation unit comprising:

a prescale computation unit configured to multiply said matrix of DCT coefficients by a symmetric pre-scale factor array to produce a pre-scaled array;

a row vector computation unit configured to perform an intermediary calculation row-wise upon said pre-scaled array to obtain an intermediary array; and

a column vector computation unit configured to perform a final calculation column-wise upon said intermediary array to provide data representative of said video image;

wherein said row vector computation unit is configured to calculate;

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a row vector of said pre-scaled array.

31. The inverse discrete cosine transform calculation unit as recited in claim 30 further comprising a memory for storing each DCT coefficient of said matrix of DCT coefficients.

32. The inverse discrete cosine transform calculation unit as recited in claim 30 wherein said column vector computation unit is configured to calculate:

v0=b0+b4;

v4=b0-b4

v2=b6*tan(π

*2/16)+b2;

v6=b6-b2*tan(π

*2/16);

v7=b1*tan(π

*1/16)-b7;

v1=b1+b7*tan(π

*1/16);

v5=-b3*tan(π

*3/16)+b5;

v3=b3+b5*tan(π

*3/16);

b0=v0+v2;

b2=v0-v2;

b4=v4+v6;

b6=v4-v6;

b3=v7+v5;

b5=(v7-v5);

b1=(v1-v3);

b7=v1+v3;

v5=(b1+b5)*cos(π

*4/16);

v1=(b1-b5)*cos(π

*4/16);

output[0]=(b0+b7);

output[7]=(b0-b7);

output[1]=(b6+v5);

output[6]=(b6-v5);

output[2]=(b4+v1);

output[5]=(b4-v1);

output[3]=(b2+b3);

output[4]=(b2-b3);

wherein input parameters b0-b7 represent coefficients of a column vector of said intermediary array.