Apparatus for inverse discrete cosine transform

• US 5,724,278 A
• Filed: 12/06/1995
• Issued: 03/03/1998
• Est. Priority Date: 12/06/1994
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ohgose, Hideyuki, Nada, Takatoshi
• Primary Examiner(s): Mai, Tan V.
• Application Number:
  US08/568,096
• Time in Patent Office: 818 Days
• Field of Search: 364/725.02, 364/725.01
• US Class Current: 708/401
• 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

Abstract

An inverse discrete cosine transform apparatus has operation units for operating a combination of plural basic operation matrixes, including rearrangement, addition, subtraction and multiplication. A coefficient C of multiplication is defined as C=cos (nπ/16) (n:integer), and the basic operation matrixes are represented by equation (6), and operations of matrixes of addition and subtraction are carried out prior to operations of respective matrixes of multiplication.

Claims

1. An inverse discrete cosine transform (DCT) apparatus for carrying out a one-dimensional inverse discrete cosine transform by combining plural matrix operation means for operating basic operation matrixes of rearrangement, addition and subtraction, multiplication and shift, said inverse discrete cosine transform apparatus comprising:

operation means for performing operations wherein an inverse DCT coefficient C_n is represented by C_n =cos (nπ

/16) (n;

integer), and said plural basic operation matrixes produce a first output signal, a second output signal, a third output signal, a fourth output signal, a fifth output signal, a sixth output signal, a seventh output signal and an eighth output signal from a first input signal, a second input signal, a third input signal, a fourth input signal, a fifth input signal, a sixth input signal, a seventh input signal and an eighth input signal by using the following equation;

##EQU11## and said operation means comprises a rearrangement operation part for carrying out rearrangement according to a first operation matrix M₂₇, a first addition and subtraction operation part for carrying out addition and subtraction according to a second operation matrix M₂₆, a first multiplication operation part for carrying out multiplication according to a third operation matrix M₂₅, a second addition and subtraction operation part for carrying out addition and subtraction according to a fourth operation matrix M₂₄, a second multiplication operation part for carrying out multiplication according to a fifth operation matrix M₂₃, a third addition and subtraction operation part for carrying out addition and subtraction according to a sixth operation matrix M₂₂, and a fourth addition and subtraction operation part for carrying out addition and subtraction according to a seventh operation matrix M₂₁, wherein a shift rightward occurs for respective results of said seven operations according to the respective operation matrixes by one bit,

said operation means carrying out operations of said basic operation matrixes of addition and subtraction prior to operations of respective basic operation matrixes of multiplication.

2. An inverse discrete cosine transform apparatus in accordance with claim 1 further comprising:

two-dimensional inverse discrete cosine transform apparatus for producing a two-dimensional output signal from a two-dimensional input signal by using operation matrixes obtained by tensor product operation of said basic operation matrixes in said equation.

3. An inverse discrete cosine transform apparatus for carrying out two-dimensional inverse discrete cosine transform by using a row-column transform method in which a one-dimensional inverse discrete cosine transform is carried out with respect to row direction and column direction of a two-dimensional input signal and a two-dimensional output signal is output, the apparatus comprising:

an operating unit of matrixes M₃₄ -M₃₉ for carrying out in row direction a rearrangement operation according to a first operation matrix M₃₉, an addition and subtraction operation according to a second operation matrix M₃₈, a multiplication operation according to a third operation matrix M₃₇, an addition and subtraction operation according to a fourth operation matrix M₃₆, a multiplication operation according to a fifth operation matrix M₃₅, and an addition and subtraction operation according to a sixth operation matrix M₃₄,

a transposition part for holding output data of said operation unit of matrixes M₃₄ -M₃₉ and outputting said output data by interchanging row and column,

an operating unit of matrixes M₃₄ -M₃₉ for carrying out in column direction a rearrangement operation according to the first operation matrix M₃₉, an addition and subtraction operation according to the second operation matrix M₃₈, a multiplication operation according to the third operation matrix M₃₇, an addition and subtraction operation according to the fourth operation matrix M₃₆, a multiplication operation according to the fifth operation matrix M₃₅, and an addition and subtraction operation according to the sixth operation matrix M₃₄,

an operating unit of matrixes M₃₁ -M₃₃ of two-dimensional operation for carrying out a multiplication operation according to an operation matrix obtained by deriving a tensor product from a seventh operation matrix M₃₃, a multiplication operation according to an operation matrix obtained by deriving a tensor product from an eighth operation matrix M₃₂, and an addition and subtraction operation according to an operation matrix obtained by deriving a tensor product from a ninth operation matrix M₃₁, so that the two-dimensional inverse discrete cosine transform is carried out by combining a row-column transposition method and the two-dimensional operation by tensor product on the basis of one-dimensional inverse discrete cosine transforms represented by the following equation;

##EQU12##

4. An inverse discrete cosine transform apparatus in accordance with claim 3 further comprising:

a selector for selecting one of a two-dimensional input signal and the output signal of said transposition part,

a demultiplexer for selecting one data output from said operating unit in row direction, said operating unit in column direction, said transposition part, and said operating unit of matrixes M₃₁ -M₃₃, and outputting to operating unit of tensor product or said transposition part, so that the two-dimensional inverse discrete cosine transform is carried out by performing operation in row direction by operation in column direction by controlling a timing.

5. An inverse discrete cosine transform (IDCT) apparatus for performing a one-dimensional IDCT, the apparatus comprising:

means for combining plural matrix operation means for operating basic operation matrixes of rearrangement, addition and subtraction, multiplication and shift;

operation means for performing operations wherein an IDCT coefficient C_n is represented by C_n =cos (nπ

/16) (n;

integer); and

means for generating a first output signal, a second output signal, a third output signal, a fourth output signal, a fifth output signal, a sixth output signal, a seventh output signal and an eighth output signal from a first input signal, a second input signal, a third input signal, a fourth input signal, a fifth input signal, a sixth input signal, a seventh input signal and an eighth input signal by using the following equation;

##EQU13## said operation means including;

a rearrangement operation part for carrying out rearrangement according to a first operation matrix M₂₇,

a first addition and subtraction operation part for carrying out addition and subtraction according to a second operation matrix M₂₆,

a first multiplication operation part for carrying out multiplication according to a third operation matrix M₂₅,

a second addition and subtraction operation part for carrying out addition and subtraction according to a fourth operation matrix M₂₄,

a second multiplication operation part for carrying out multiplication according to a fifth operation matrix M₂₃,

a third addition and subtraction operation part for carrying out addition and subtraction according to a sixth operation matrix M₂₂, and

a fourth addition and subtraction operation part for carrying out addition and subtraction according to a seventh operation matrix M₂₁,

wherein a shift rightward occurs for respective results of said seven operations according to the respective operation matrixes by one bit,

said operation means carrying out operations of said basic operation matrixes of addition and subtraction prior to operations of respective basic operation matrixes of multiplication.

6. An inverse discrete cosine transform apparatus in accordance with claim 5 further comprising:

two-dimensional inverse discrete cosine transform apparatus for producing a two-dimensional output signal from a two-dimensional input signal by using operation matrixes obtained by tensor product operation of said basic operation matrixes in said equation.