JPH02224489A - Encoding and decoding device - Google Patents

Abstract

PURPOSE:To avoid useless time and to quicken the processing of one pattern by providing an arithmetic controller controlling the calculation of orthogonal conversion and inverse orthogonal conversion as to sn effective element only. CONSTITUTION:A highly efficient encoding and decoding device is provided with a frequency component detector g detecting the frequency component of a conversion coefficient and a controller 10 controlling the calculation of inversion orthogonal conversion. The processing of 4 picture elements X 4 picture elements as the picture data is considered. In this case, the conversion coefficients by orthogonal conversion are expressed as a 4X4 matrix as shown in figure using a component D1 at the upper left of the matrix as the DC component. Suppose that the effective element (element not zero) of the conversion coefficient appears in D1, D2 and D3 only and the other elements are zero, then a frequency component detector 9 sends the information shown in figure (2) as the frequency component data to the inverse orthogonal conversion control circuit 10. The controller 10 applies control so that the matrix calculation in the inverse orthogonal conversion is applied only to a 2X2 matrix having the effective element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a highly efficient encoding/decoding device that compresses information of a television signal using orthogonal transformation.

[Conventional technology]

In conventional high-efficiency encoding/decoding equipment for television signals,
As a method of information compression, I.E.E.
Transactions on Computers, 1974
There is an orthogonal transform typified by the discrete cosine transform (DCT), which is discussed on pages 90 to 93 of this year.

When performing orthogonal transformation on the image signal, - 1 for boat fishing
The image is divided into blocks of nxm pixels. Here, one block of nxm pixels is represented by a matrix [P], and orthogonal transformation is performed using an orthogonal transformation matrix [T].

[C:] = [T] [P] ['l'l'
...(1) [T]' is the transposed matrix of [T], and for the 0 image from which the transformation coefficient [C] is obtained, D
It is well known that when CT is performed, information is concentrated in low-order frequency components.

Further, the inverse orthogonal transformation to obtain one image data [P] from the transformation coefficients [C] is performed using the inverse orthogonal transformation matrix [R].

[Pco = [R] IO3[R]'
...(2) [R]' is obtained by calculating the transposed matrix of [R].

A high-efficiency encoding/decoding device that uses orthogonal transformation as an information compression method performs matrix operations as shown in equations (1) and (2). and inverse orthogonal transformation, and the sum of products is performed 2n'' times.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not utilize the property that the transformation coefficient matrix [C] has information concentrated in low-order frequency components and zero in high-order components in the matrix calculation of the inverse orthogonal transform, resulting in unnecessary calculations. I had time.

An object of the present invention is to speed up screen processing without wasting time by performing matrix operations of orthogonal transformation and inverse orthogonal transformation only on effective elements.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a coefficient matrix [C]
Add a part to detect the frequency components of.

By giving this information to the inverse orthogonal transformer, only the effective elements (non-zero elements) in the coefficient matrix [C] are operated.

[Effect]

The frequency component detector operates to detect significant elements in the transform coefficient matrix [0]. As a result, the inverse orthogonal transformer performs product-sum operations only on effective elements, eliminating unnecessary operations.

You can speed up the processing time for one screen.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 1. The portion surrounded by dotted lines in FIG. It is.

First, a conventionally known high-efficiency encoder will be explained. The Te1 Novi signal input by port 1 is A/
The D-conversion conversion is converted into a digital signal. The digitized television signal is divided into blocks of m pixels x n pixels and taken into the block memory 3 as image data. The orthogonal transformer 4 extracts image data block by block and performs orthogonal transformation. The orthogonally transformed image data will be referred to as transformation coefficients. The transform coefficients are encoded by an encoder 5 and sent to a transmission path 6.

The decoder 7 decodes the code and creates transform coefficients. The inverse orthogonal transformer 8 creates one block of image data by performing inverse orthogonal transformation on the decoded transform coefficients, writes it into the block memory 11, sequentially reads out the image data in the block memory 11, and converts the data into the D/A. converter 12 as an analog television signal.

One or more outputs to the boat 13 are operations and processing steps of a high-efficiency encoding/decoding device using orthogonal transformation.

Next, the features of the present invention surrounded by dotted lines will be explained.1 The efficiency encoding/decoding device of the present invention includes a frequency component detector 9 that detects frequency components of transform coefficients, and a frequency component detector 9 that controls the calculation of inverse orthogonal transform. Control to! I! It is characterized by the addition of 11o.

To explain the actual operation, consider processing of a block of 4 pixels x 4 pixels as image data. At this time, the transform coefficients resulting from the orthogonal transform become a 4×4 matrix with the upper left DI as the DC component, as shown in FIG. Suppose that the effective elements (non-$ elements) of the conversion coefficients are Di, D2 . D3. Assuming that the other elements are zero, the frequency component detector 9 sends the information marked ■ in FIG. 2 as frequency component data to the inverse orthogonal transform control circuit 10. The controller 10 controls the inverse orthogonal transform matrix operation to be performed only on 2×2 matrices with valid elements.

FIG. 3 shows an example of a specific circuit configuration.First, the frequency component detector 9 is shown in FIG. 3(a).

The comparator 9a determines whether an element in the conversion coefficient is a valid element (not zero) or an invalid element (field coefficient). If it is a valid element, its address is stored for 1 d in the address memory 9c. When processing is performed on frequency component elements from DC to higher order for one block of conversion coefficients, the address containing the highest order frequency component is stored in the address memory 9c. Based on this address, the frequency component detection Rom 9d creates one frequency component data. In the example of FIG. 2, the highest order frequency component element is D3, and the address memory 9d has a six frequency component detection ROM 9d containing 3'.

Input Output 0 ・・・・・・・・・・・・・・・■1...
・・・・・・・・・・・・・・・■2～3・・・・・・
・・・・・・・・・・・・■4～6・・・・・・・・・
・・・・・・・・・■１０～１６・・・・・・・・・・・・
... It is configured to output ■, and the frequency component data has a value ■.

Further, FIG. 3(b) shows an example of the configuration of the inverse orthogonal transformer 8 and the controller.

Only valid elements of the conversion coefficients enter the shift register 8a in an appropriate order. The coefficient Rom8b contains data of an inverse orthogonal transformation matrix, and is subjected to matrix calculation by the product-sum calculator 8C. In the two-dimensional inverse orthogonal transformation, image data is obtained by further performing matrix operations on the results using a similar configuration.

In the example of FIG. 2, the effective elements L)1. of the conversion coefficients are stored in the shift register 8a. D2. D3 enters in order, performs a matrix operation with the inverse orthogonal transformation matrix data, and puts the result into the shift register 8d.

Furthermore, using the product-sum calculator 8f, matrix calculations are performed to obtain five image data (i=1 to 4 degrees and j=1 to 4).

FIG. 4 shows an example in which a controller 10 is provided which controls the calculation based on the accumulation of data in the buffer in the decoder 7 instead of the frequency component data. When a large amount of data is accumulated in the buffer, processing can be performed by treating only the low frequency components of the transform coefficients as valid elements.
Speed up block processing.

Although the example on the receiving side has been shown above, the orthogonal transformer on the transmitting side can be considered in the same way.

The encoder 5, an example of which is shown in FIG. Give +14. The controller 14 is.

The calculation of the orthogonal transformer 4 is controlled to create only necessary frequency component elements as transform coefficients.

Terminating orthogonal transformation or inverse orthogonal transformation at a certain frequency component directly affects the image. Conversely, by specifying the desired resolution of the image, it is possible to abort orthogonal transformation and inverse orthogonal transformation at appropriate frequency components. An example of this is shown in FIG. 6. Each sender or receiver sends a resolution element signal to the controller indicating how much resolution an image is desired. Depending on the signal, the controller determines up to which frequency component the conversion coefficients are to be created, or at which frequency component the conversion coefficient is to be terminated.

In FIG. 6(a), the sender determines the quality of the image to be transmitted and inputs it to the controller 14 as a resolution element signal. The controller 14 determines the frequency components of the transform coefficients according to the signal, and controls the orthogonal transformer 4 that performs orthogonal transform operations.

In FIG. 6(b), the recipient determines the required image quality. The receiver inputs the required image quality to the controller 10 as a resolution request signal.

The controller 10 controls the inverse orthogonal transformer 8 to perform inverse orthogonal transformation up to a certain frequency component according to the signal.

〔Effect of the invention〕

According to the present invention, orthogonal transform and inverse orthogonal transform are performed only on valid elements, so that the effect of speeding up the processing can be obtained. Using the example in Figure 2, the conventional inverse orthogonal transformation for creating image data from transform coefficients is
Although 28 product-sum calculations were required, the apparatus of the present invention can create image data equivalent to the conventional method with 48 product-sum calculations.

In addition, the device of the present invention can create orthogonal transformation coefficients up to a certain frequency component from image data, or conversely can concentrate 5 image data from orthogonal transformation coefficients up to a certain frequency component, so the image resolution can be adjusted.

That is, a high-resolution image can be obtained by performing orthogonal transformation up to high frequency components and performing inverse orthogonal transformation without cutting off bright frequency components. Furthermore, if only low frequency components are created by orthogonal transformation, or if inverse orthogonal transformation is terminated at low frequency components, an image with low resolution will be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram showing an example of specific conversion coefficients, and Fig. 3 is a block diagram showing the circuit configuration of the main part of the embodiment of the present invention. , FIGS. 4 to 6 are block diagrams of other embodiments of the present invention. 4... Orthogonal transformer, 5... Encoder, 7... Decoder, 8... Inverse orthogonal transformer, 9... Frequency component detector,
10... Inverse orthogonal transformation controller, 14... Orthogonal transformation controller. Atsumi Kaya (Nou (b)

Claims (1)

[Scope of Claims] 1. An encoding/decoding device using orthogonal transform, characterized in that an arithmetic controller is provided to control orthogonal transform and inverse orthogonal transform operations to be performed only on effective elements. encoding/decoding device. 2. The encoding/decoding apparatus according to claim 1, further comprising an effective element frequency component detector for detecting an effective element of a transform coefficient in order to detect the effective element. 3. An encoding/decoding device having a function of adjusting the resolution of an image by terminating the transformation at a certain frequency component by the orthogonal transformation or inverse orthogonal transformation according to claim 1.