US 5,629,882 A · Discrete cosine transformation system and inverse discrete cosine transformation system, having simple structure and operable at high speed

Abstract

An 8.times.8 discrete cosine transformation (8.times.8 DCT) system with minimum multiplications, without a reduced accuracy of calculation, and operable at a high speed, and an 8.times.8 inverse discrete cosine transformation (IDCT) system are disclosed. The transformation matrices for an 8.times.8 DCT are factorized into a constant matrix [Q] and a matrix [R], and the relationship between the original input data [X] and the output matrix data [C] can be defined by [C]=1/2.multidot.[R] [Q] [X]. The matrix [Q] consists of 0, 1, and -1, while the matrix [R] consists of irrational numbers defined by the 8.times.8 DCT. The computation of the constant matrix [Q] to the matrix data [X] can be realized by an addition and subtraction operation, while multiplication is performed just for the computation of the matrix [R]. The addition and subtraction circuit performs a computation between [X] and [Q], while the multiplication and addition circuit performs a computation between the result of computation of the addition and subtraction circuit and the matrix [R]. Also, an 8.times.8 IDCT performs the computation inverse to the 8.times.8 DCT.

Claims14

Dependent claims

A two-dimensional 8 row.times.8 column discrete cosine transformation device for performing a transformation in accordance with the following formula:

[C]=1/2[R] [Q] [X]
where, [X] denotes matrix data to be subjected to the discrete cosine transformation and is defined as follows:
##EQU12## [C] denotes matrix data obtained by the discrete cosine transformation and is defined as follows:
##EQU13## [Q] denotes an 8.times.8 constant matrix and is defined as follows:
##EQU14## [R] denotes an 8.times.8 matrix and is defined as follows:
##EQU15## wherein, A=cos (.pi./4),
B=cos (.pi./8),
C=cos (3.pi./8),
D=cos (.pi./16),
E=cos (3.pi./16),
F=cos (5.pi./16), and
G=cos (7.pi./16)
said device comprising:
first computing means for computing a matrix [S]=[Q] [X], where, [S]0=s.sub.j (j=0-7);
second computing means for computing a matrix [T]=[R] [S] where, [T]=t.sub.j (j=0-7);
and
shifting means for shifting the matrix [T] by one bit, to obtain the matrix [C]=[T]/2.

14 more elements

A two-dimensional 8 row.times.8 column inverse discrete cosine transformation device for performing a transformation in accordance with the following formula:

[x]=1/2[Q.sup.t ] [R.sup.t ] [C]
where, [C] denotes matrix data to be subjected to the inverse discrete cosine transformation and is defined as follows:
##EQU16## [X] denotes matrix data obtained by the inverse discrete cosine transformation and is defined as follows:
##EQU17## [R.sup.t ] denotes an 8.times.8 matrix and is defined as follows:
##EQU18## wherein, A=cos (.pi./4),
B=cos (.pi./8),
C=cos (3.pi./8),
D=cos (.pi./16),
E=cos (3.pi./16),
F=cos (5.pi./16), and
G=cos (7.pi./16)
[Q.sup.t ] denotes an 8.times.8 constant matrix and is defined as follows:
##EQU19## said device comprising:
a first computing means for computing a matrix [T]=[R.sup.t ].multidot.[C], where, [T]=t.sub.j (j=0-7);
a second computing means for computing a matrix [S]=[Q.sup.t ].multidot.[T], where, [S]=S.sub.j (j=0-7);
and
a shifting means for shifting the matrix [S] by one bit to thereby obtain the matrix [X]=[S]/2.

14 more elements

Dependencies are inferred from the claim text.

Discrete cosine transformation system and inverse discrete cosine transformation system, having simple structure and operable at high speed

Life of this patent

Discrete cosine transformation system and inverse discrete cosine transformation system, having simple structure and operable at high speed

Life of this patent

Abstract

Claims14