JPH0454730A - Encoder - Google Patents

Abstract

PURPOSE:To save a data quantity at an area not imparting much effect onto picture quality by using an absolute value processor and an accumulator so as to control a multiplier. CONSTITUTION:An input signal 1 is subjected to orthogonal transformation by an orthogonal transformer 2, the result is fed to an absolute value processor 4 and an accumulator 6, from which a signal 7 being the accumulated signal of an absolute value is calculated. The accumulation is implemented in the unit of a block of orthogonal transformation. The signal 7 is given to a multiplier generator 8, in which the signal is mapped to one of some multipliers and a selected multiplier is outputted as a multiplier 9. The multiplier 9 is multiplied with a signal retarding the signal 3 by a multiplier 12 and the product signal is given to a coder 14, in which the signal is coded. The multiplier 9 is coded simultaneously as the signal 13 and the result is used for correct decoding at a decoder.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a means for reducing the amount of data required to transmit and store image signals in order to reduce communication costs and extend recording time. The present invention relates to an encoding device.

Conventional technology A block diagram of a conventional encoding device is shown in FIG.

In the figure, l is an input signal, 2 is an orthogonal transformer that orthogonally transforms input signal 1, 3 is a signal that has been orthogonally transformed by orthogonal transformer 2, 14 is an encoder that encodes signal 3, and 15 is a code This is the output signal encoded by encoder 4.

In the conventional encoding device configured as described above, the input signal l is orthogonally transformed by the orthogonal transformer 2. By choosing an appropriate function for this orthogonal transformation, it is possible to make certain transformation components smaller than other components, and as proven in information theory, signals with strong correlations such as image signals can be significantly reduced. Data amount can be reduced. Furthermore, when using DcT (I-scattered cosine transform) as an orthogonal transformation, the distortion for high-frequency components is visually less noticeable than the distortion for low-frequency components. The amount of data can be reduced.

Problems to be Solved by the Invention However, in the above configuration, the characteristics of the local distribution of the image (high frequency areas and low frequency areas are spatially concentrated) are not used at all. , there is still room to reduce the amount of data.

In view of this, an object of the present invention is to provide an encoding device that further reduces the amount of data compared to conventional encoding devices without substantially degrading image quality.

Means for Solving the Problems The present invention provides orthogonal transformation means for orthogonally transforming an input signal, absolute value calculation means for calculating the absolute value of an output signal of the orthogonal transformation means, and orthogonal transformation of the output signal of the absolute value calculation means. a cumulative addition means for cumulatively adding each time, a multiplication means for multiplying the output signal of the orthogonal transform by a function of the output of the cumulative addition means, and an encoding means for encoding the multiplier of the multiplier and the output of the multiplication means. This is an encoding device characterized by the following. Further, an orthogonal transform means for orthogonally transforming an input signal, a code amount prediction means for calculating a code amount estimate value when the output signal of the orthogonal transform means is encoded, and a code amount prediction means for calculating an estimated code amount when the output signal of the orthogonal transform means is encoded; The encoding device is characterized by comprising a multiplication means for multiplying by a function, and an encoding means for encoding the multiplier of the multiplier and the output of the multiplication means. Furthermore, orthogonal transformation means for orthogonally transforming the input signal, absolute value calculation means for calculating the absolute value of the output signal of the orthogonal transformation means, and cumulative addition means for cumulatively adding the output signal of the absolute value calculation means for each orthogonal transformation. and encoding means for controlling the compression rate for encoding the orthogonal transform output signal by the output of the cumulative addition means and encoding the control information at the same time. and an orthogonal transform means for orthogonally transforming an input signal, a code amount prediction means for calculating an estimated code amount when the orthogonal transform means output signal is encoded, and a compression rate for encoding the orthogonal transform output signal. The encoding device is characterized in that it includes encoding means that performs control based on the output of the code amount prediction means and encodes the control information at the same time.

Operation The present invention reduces the amount of data by changing the multiplier of the multiplier or changing the compression ratio based on a certain criterion for the orthogonally transformed components using the above-described configuration. Human vision has the characteristic that encoding distortion is difficult to detect when the absolute value of a specific frequency is large, and distortion is difficult to detect when fluctuations in frequency components are large. Therefore, by reducing the amount of data compared to the conventional method when the distortion is difficult to understand, it becomes possible to reduce the average amount of data with almost no loss in image quality. The first invention is a cumulative sum of absolute values, and the second invention is a multiplier for multiplying by the estimated code amount value (generally, the absolute value of a component and the code amount are linked). is under control.

Further, the third invention controls the compression ratio of the encoding means using the cumulative sum of absolute values, and the fourth invention controls the compression ratio of the encoding means using the value of the estimated code amount.

Embodiment FIG. 1 is a block diagram of an encoding device in an embodiment of the first invention. In the figure, l is an input signal, 2 is an orthogonal transformer that orthogonally transforms input signal 1 and outputs orthogonally transformed signal 3, and 4 is an absolute value converter that calculates the absolute value of signal 3 and outputs absolute value signal 5. 6 is a cumulative adder that cumulatively adds signal 5 and outputs cumulative sum signal 7; 8 is a multiplier generator that converts signal 7 to multiplier 9; lO is an absolute value converter 4 for signal 3, and cumulative adder 6 and a delay device that outputs a signal 11 delayed by the processing time of the multiplier generator 8; 12 a multiplier that multiplies the signal 11 by a multiplier 9 and outputs a product signal 13; and 14 a signal that encodes the multiplier 9 and the signal 13. This encoder outputs an output signal 15.

The operation of the encoding device of this embodiment configured as described above will be described below. Human power signal l is orthogonal transformer 2
After the signal is orthogonally transformed, an absolute value converter 4 and a cumulative adder 6 calculate a signal 7 which is a cumulative addition signal of absolute values. This cumulative addition is performed in units of orthogonal transform blocks. Signal 7 is mapped to one of several multipliers in multiplier generator 8, with the selected multiplier being multiplier 9. The signal 3 delayed by the multiplier 12 is multiplied by a multiplier 9 and encoded by the encoder 14. The multiplier 9 is also encoded simultaneously with the signal 13 and is used by the decoding device for correct decoding. FIG. 2 is a block diagram of a decoding device that decodes a signal encoded by the encoding device of this embodiment, where 15 is an input signal, and 16 is a signal 17 (signal 13) obtained by decoding the input signal 15. 19 is a divider that outputs a quotient signal 20 obtained by dividing the signal 17 by the divisor 18, and 21 performs the inverse transformation of the orthogonal transformer 2 and outputs it. signal 2
This is an orthogonal transformer that outputs 2. The operation of this decoding device is self-explanatory and will therefore be omitted, but if this decoding device is used, the signal encoded by the encoding device of this embodiment can be easily decoded.

As described above, according to this embodiment, by controlling the multiplier using the absolute value converter 4 and the cumulative adder 6, it is possible to reduce the amount of data in areas that have little influence on image quality.

FIG. 3 is a block diagram of an encoding device in an embodiment of the second invention. In the figure, l is an input signal, 2 is an orthogonal transformer that orthogonally transforms the input signal l and outputs an orthogonal transformed signal 3, and 23 is an estimated value signal that calculates an estimated code amount when signal 3 is encoded. 8 is a multiplier generator that converts signal 24 into multiplier 9; 10 is signal 3;
12 is a delay device that outputs a signal 11 that is delayed by the processing time of the code amount predictor 23 and the multiplier generator 8;
a multiplier 14 that multiplies by a multiplier 9 and outputs a product signal 13;
is an encoder that encodes the multiplier 9 and the signal 13 and outputs the output signal 15.

The operation of the encoding device of this embodiment configured as described above will be described below. Input signal 1 is orthogonal transformer 2
After orthogonal transformation, the code amount predictor 23 calculates signal 7, which is the estimated code amount when signal 3 is encoded.

This code amount estimation value is performed in units of orthogonal transform blocks. Signal 24 is mapped to one of several multipliers in multiplier generator 8, with the selected multiplier being multiplier 9. The signal 3 delayed by the multiplier 12 is multiplied by a multiplier 9 and encoded by the encoder 14. The multiplier 9 is also encoded simultaneously with the signal 13 and is used by the decoding device for correct decoding. The same decoding device as in the first embodiment can be used. Since the code amount estimate value is not a direct function of image quality, the first embodiment is better in the sense of keeping the image quality constant across the band, but it is better to keep the code amount constant within a certain range. This embodiment has better control over lengthening. Note that the estimated code amount does not necessarily need to be calculated accurately, and a function that can approximate the code amount may be used.

As described above, according to this embodiment, by controlling the multiplier using the code amount predictor, it is possible to reduce the amount of data in areas that have little effect on image quality.

FIG. 4 is a block diagram of an encoding device in an embodiment of the third invention. In the figure, l is an input signal, 2 is an orthogonal transformer that orthogonally transforms input signal 1 and outputs orthogonally transformed signal 3, and 4 is an absolute value converter that calculates the absolute value of signal 3 and outputs absolute value signal 5. 6 is a cumulative adder that cumulatively adds signals 5 and outputs a cumulative sum signal 7; 25 is a compression controller that generates compression parameters 26 for controlling the encoder; 10 is a signal 3;
a delay device 1 that outputs a signal 11 that is delayed by the processing time of the absolute value converter 4, the cumulative adder 6, and the compression controller 25;
4 is an encoder that encodes the signal 11 using compression parameters 26 and outputs an output signal 15.

Regarding the encoding device of this embodiment configured in the above keyaki,
The operation will be explained below. Orthogonal transformer 2, absolute value converter 4
, the accumulative adder 6 operates in the same manner as in the embodiment shown in FIG. 1, so a description thereof will be omitted. When the cumulative sum is large, it is difficult to visually detect even if the compression ratio is slightly increased and the encoding distortion increases. Therefore, by controlling the compression controller 25, the compression parameter 26 can be controlled to increase the compression ratio, thereby reducing the amount of data. The output signal 15 is the compression controller 25
The compression ffI controller 25 controls the compression parameters so that the average code amount becomes constant. That is, signal 7
The compression ratio is increased when the average amount of data is large or the average amount of data is large, and the compression ratio is decreased when the average amount of data is small. When controlling the compression rate so that the average data amount is constant, the first
The multiplier and multiplier encoding means of the embodiment are not required, and the configuration is simplified.

As described above, according to this embodiment, by controlling the compression rate using the cumulative sum and average data amount using the absolute value converter, cumulative adder, and compression controller, the compression ratio can be easily achieved without deteriorating the image quality. The amount of data can be reduced.

FIG. 5 is a block diagram of an encoding device in an embodiment of the fourth invention. In the figure, 1 is an input signal, 2 is an orthogonal transformer that orthogonally transforms input signal 1 and outputs orthogonal transformed signal 3, and 23 is an estimated value signal that calculates the estimated code amount when signal 3 is encoded. 25 is a compression controller that generates a compression parameter 26 for controlling the encoder; 10 is a signal obtained by delaying signal 3 by the processing time of the code amount predictor 23 and compression controller 25; 14 is an encoder that encodes the signal 11 using the compression parameter 26 and outputs the output signal 15.

Regarding the encoding device of this embodiment configured as described above,
The operation will be explained below. Since the orthogonal transformer 2 and the code amount predictor 23 operate in the same manner as in the embodiment shown in FIG. 3, their explanation will be omitted. When the code amount estimate is large, it is difficult to visually detect even if the compression ratio is slightly increased and the encoding distortion increases. Therefore, by controlling the compression controller 25, the compression parameter 26 can be controlled to increase the compression ratio, thereby reducing the amount of data. The output signal 15 is the compression controller 25
The compression controller 25 controls the compression parameters so that the average code amount is constant. That is, when the signal 24 is large or the average amount of data is large, the compression ratio is increased, and when the average amount of data is small, the compression ratio is decreased.

When controlling the compression rate so that the average data amount is constant, the second
The multiplier and multiplier encoding means of the embodiment are not required, and the configuration is simplified.

As described above, according to this embodiment, by controlling the compression rate using the code amount estimate and the average data amount using the code amount predictor and compression controller, the data amount can be easily controlled without deteriorating the image quality. can be reduced.

In the embodiments of the present invention, a transform having coefficients similar to the orthogonal transform may be used instead of the orthogonal transform. Also,
In the first embodiment and the third embodiment, the control based on the cumulative sum of absolute values may be made an integral multiple of the block unit of the orthogonal transform, and in the second embodiment and the fourth embodiment, the control based on the code amount estimation value may be used. Control may be performed using the sum of code amount estimates of a plurality of coding units. Furthermore, the first embodiment and the second embodiment, and the third embodiment and the fourth embodiment may be used together to increase the implementation effect.

Effects of the Invention As explained above, according to the present invention, it is possible to reduce the amount of data with almost no loss in image quality, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the encoding device in the first invention, FIG. 2 is a block diagram of the decoding device of the same embodiment,
3 is a block diagram of the encoding device of the second invention, FIG. 4 is a block diagram of the encoding device of the third invention, and FIG. 5 is the block diagram of the encoding device of the third invention.
FIG. 6 is a block diagram of a conventional encoding device. 4... Absolute value converter, 6... Cumulative adder, 8... Multiplier generator, 14... Encoder, 23... ...Code amount predictor, 25...
Compression controller. Name of agent: Patent attorney Shigetaka Awano

Claims (8)

[Claims] (1) Orthogonal transformation means for orthogonally transforming an input signal, absolute value calculation means for calculating the absolute value of the output signal of the orthogonal transformation means, and cumulative addition for cumulatively adding the output signal of the absolute value calculation means for each orthogonal transformation. a multiplication means for multiplying the orthogonal transform output signal by a function of the output of the cumulative addition means; and an encoding means for encoding the multiplier of the multiplier and the output of the multiplication means. Device. (2) Claim (1) where the multiplier is made smaller when the cumulative addition output is large and the multiplier is made larger when the cumulative addition output is small.
) described encoding device. (3) orthogonal transform means for orthogonally transforming an input signal; code amount predicting means for calculating a code amount estimate when the output signal of the orthogonal transform means is encoded; and code amount predicting means for orthogonally transforming the orthogonal transform output signal. An encoding device comprising: a multiplier for multiplying by a function of an output; and an encoding means for encoding the multiplier of the multiplier and the output of the multiplier. (4) Claim (3) where the multiplier is made small when the code amount estimate is large and the multiplier is made large when the code amount estimate is small.
) described encoding device. (5) orthogonal transformation means for orthogonally transforming an input signal; absolute value calculation means for calculating the absolute value of the output signal of the orthogonal transformation means; and cumulative addition for cumulatively adding the output signal of the absolute value calculation means for each orthogonal transformation. and encoding means for controlling the compression ratio for encoding the orthogonal transform output signal by the output of the cumulative addition means and encoding the control information at the same time. (6) Claim in which the compression ratio is increased when the cumulative addition output is large and the compression ratio is decreased when the cumulative addition output is small (
5) The encoding device described. (7) Orthogonal transform means for orthogonally transforming an input signal, code amount prediction means for calculating a code amount estimate when the output signal of the orthogonal transform means is encoded, and a compression ratio for encoding the orthogonal transform output signal. An encoding device characterized by comprising encoding means for controlling the output of the code amount predicting means and encoding the control information at the same time. (8) Claim in which the compression rate is increased when the code amount estimate is large and the compression rate is decreased when the code amount estimate is small (
7) The encoding device described.