WO2011064932A1

WO2011064932A1 - Image encoding device and image decoding device

Info

Publication number: WO2011064932A1
Application number: PCT/JP2010/005919
Authority: WO
Inventors: 杉本　和夫; 裕介伊谷; 彰峯澤; 関口　俊一
Original assignee: 三菱電機株式会社
Priority date: 2009-11-30
Filing date: 2010-10-01
Publication date: 2011-06-03
Also published as: JPWO2011064932A1

Abstract

In the provided image encoding device, an image size-reduction unit (201) reduces the size of a macroblock image and outputs a size-reduced image. A prediction-image transformation/quantization unit (202) performs a frequency transformation on the size-reduced image, quantizes said image, and outputs first intra prediction data. A prediction-image reverse-quantization/reverse-transformation unit (203) performs reverse quantization and a reverse frequency transformation on the first intra prediction data and outputs a locally-decoded prediction image. A prediction-image enlargement unit (204) enlarges the locally-decoded prediction image to generate a first intra prediction image. An original-image difference computation unit (102) outputs a differential image representing the difference between the macroblock image and the first intra prediction image. A difference transformation/quantization unit (103) performs a frequency transformation on the differential image, quantizes said image, and outputs transformation coefficients. An entropy encoding unit (104) performs entropy encoding on the first intra prediction data and the transformation coefficients, outputting a bitstream.

Description

Image encoding apparatus and image decoding apparatus

The present invention relates to an image encoding device that performs intra-screen prediction when an image is compressed and transmitted and an image decoding device that decodes compressed data.

For example, H.264 recommended by ITU-T (International Telecommunication Union Telecommunication Standardization Sector). In the H.264 moving image encoding method, intra-frame redundancy is removed by performing intra-screen prediction, and a prediction error signal is compression-encoded. Conventionally, there has been an apparatus as disclosed in Patent Document 1, for example, as an encoding apparatus that performs such compression encoding and a decoding apparatus that decodes the same.

In such a conventional image encoding device, in order to generate an encoded bit stream from an input image, first, the input image is a macroblock that is an input image having a macroblock size that is a predetermined encoding unit by an image dividing unit. The image is divided into input images and processed in units of macroblocks. The macroblock input image is subtracted from the prediction image generated by the intra prediction unit by the subtraction unit, and a difference image signal obtained as a result is output. The difference image signal is input to the frequency conversion unit, converted to a conversion coefficient representing the amplitude for each frequency by performing frequency conversion, and output to the quantization unit. The transform coefficient is quantized in the quantization unit, and the quantized transform coefficient is output. The output quantized transform coefficient is entropy-encoded in the entropy encoding unit and output as an encoded bit stream. The quantized transform coefficient is also input to the inverse quantization unit. The inverse quantization unit inversely quantizes the quantized transform coefficient and outputs a decoded transform coefficient. The decoded transform coefficient is inversely frequency-converted by an inverse frequency converter, thereby obtaining a decoded difference image. The decoded difference image is added with the predicted image in the adding unit, and stored as a locally decoded image in the frame memory. The locally decoded image stored in the frame memory is used by the prediction unit to generate a predicted image.

H. performed in the prediction unit. In the H.264 intra-screen prediction method, a prediction image is generated by linearly expanding a locally decoded image of an encoded block adjacent to a block to be encoded. At this time, in the intra 4 × 4 prediction mode and the intra 8 × 8 prediction mode, the optimal prediction direction is selected from the eight types of directions and the DC prediction in which prediction is performed using the average value of surrounding pixels. select. In the intra 16 × 16 prediction mode, an optimal one is selected from a total of four types of horizontal direction, vertical direction, diagonal direction, and DC prediction.
The selected prediction mode and prediction direction are each entropy-encoded in the entropy encoder and multiplexed into the encoded bitstream.

International Publication No. 08/07500

However, in the conventional image encoding device, as described above, H.264 is used. In the H.264 intra-frame prediction, a prediction image is generated by linearly expanding a local decoded image around a block to be encoded, so that a prediction image in which a change in the peripheral local decoded image is directly formed in a straight edge shape is generated. Generated. Therefore, when the edge of the straight edge-like predicted image does not match the edge of the actual input image, a straight edge is added to the prediction error signal, resulting in a decrease in coding efficiency. That is, the conventional intra-frame prediction has a problem that the prediction efficiency is good for a video having an edge in a specific direction, and the prediction efficiency is poor for a video having an edge in another direction.

The present invention has been made to solve the above-described problems, and obtains an image coding apparatus capable of performing stable and efficient prediction regardless of the texture of the input image and improving the coding efficiency. For the purpose.

An image encoding device according to the present invention inputs a frame of image data, divides the image into a plurality of blocks, outputs a macroblock image, inputs the macroblock image, and outputs the first intra prediction image A first intra prediction unit that outputs first intra prediction data that is information for reconstructing the intra prediction image, and a difference calculation between the macroblock image and the first intra prediction image A difference image generation unit that outputs a difference image and a difference transform quantization unit that frequency-converts and quantizes the difference image and outputs a transform coefficient, entropy-encodes the first intra prediction data and the transform coefficient, and generates a bitstream. An entropy encoding unit that outputs, the first intra prediction unit reduces the macroblock image and outputs a reduced image, and frequency conversion of the reduced image Predictive image transform quantizing unit that quantizes and outputs first intra prediction data, and predictive image inverse quantization transform that outputs local decoded prediction image by dequantizing and inverse frequency converting first intra prediction data And a predicted image enlarging unit for enlarging the locally decoded predicted image and generating a first intra-screen predicted image. As a result, stable and efficient prediction can be performed regardless of the texture of the input image, and the encoding efficiency can be improved.

It is a block diagram which shows the structure of the image coding apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the image coding apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the image coding apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the image coding apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the image coding apparatus which concerns on Embodiment 3 of this invention. It is a flowchart which shows operation | movement of the image coding apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the image coding apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows operation | movement of the image coding apparatus which concerns on Embodiment 4 of this invention. It is a block diagram which shows the structure of the image coding apparatus which concerns on Embodiment 5 of this invention. It is a flowchart which shows operation | movement of the image coding apparatus which concerns on Embodiment 5 of this invention. It is a block diagram which shows the structure of the image decoding apparatus which concerns on Embodiment 6 of this invention. It is a flowchart which shows operation | movement of the image decoding apparatus which concerns on Embodiment 6 of this invention. It is a block diagram which shows the structure of the image decoding apparatus which concerns on Embodiment 7 of this invention. It is a flowchart which shows operation | movement of the image decoding apparatus which concerns on Embodiment 7 of this invention. It is a block diagram which shows the structure of the image decoding apparatus which concerns on Embodiment 8 of this invention. It is a flowchart which shows operation | movement of the image decoding apparatus which concerns on Embodiment 8 of this invention. It is a block diagram which shows the structure of the image decoding apparatus which concerns on Embodiment 9 of this invention. It is a flowchart which shows operation | movement of the image decoding apparatus which concerns on Embodiment 9 of this invention. It is a block diagram which shows the structure of the image decoding apparatus which concerns on Embodiment 10 of this invention. It is a flowchart which shows operation | movement of the image decoding apparatus which concerns on Embodiment 10 of this invention. It is explanatory drawing of the intra prediction type information of the image coding apparatus which concerns on Embodiment 4 of this invention. It is explanatory drawing which shows the other example of the intra prediction type information of the image coding apparatus which concerns on Embodiment 4 of this invention.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing an image coding apparatus according to Embodiment 1 of the present invention.
An image encoding apparatus 100 illustrated in FIG. 1 includes a block division unit 101, a first intra prediction unit (first intra prediction unit) 200, an original image difference calculation unit 102, a difference transform quantization unit 103, And an entropy encoding unit 104.
The block dividing unit 101 inputs a moving image as an original image, divides the moving image into units of macro blocks, and outputs an image of each divided macro block (hereinafter referred to as a macro block image). The first intra prediction unit 200 generates a first intra predicted image by performing intra-frame prediction, and outputs information about the predicted image as a predicted image conversion coefficient. The original image difference calculation unit 102 takes the difference between the macroblock image from the block division unit 101 and the first intra prediction image from the first intra prediction unit 200 and outputs the difference as a difference macroblock image. The difference transform quantization unit 103 performs orthogonal transform such as DCT on the difference macroblock image from the original image difference calculation unit 102, quantizes the generated orthogonal transform coefficient, and outputs a quantization coefficient. The entropy encoding unit 104 entropy-encodes the predicted image transform coefficient and the quantization coefficient by variable length encoding or arithmetic encoding, and outputs the result as a bit stream.

The first intra prediction unit 200 includes an image reduction unit 201, a predicted image transform quantization unit 202, a predicted image inverse quantization inverse transform unit 203, and a predicted image enlargement unit 204.
The image reduction unit 201 reduces the input macroblock image and outputs a reduced image. The image reduction method may be any method, for example, a method in which an average value of pixel values for every 4 × 4 pixels is used as a pixel value of a reduced image, or a sub-sampling method after applying a low-pass filter. The reduction rate may also be an inverse number of the enlargement rate in the predicted image enlargement unit 204 described later. The predicted image transform quantization unit 202 performs orthogonal transform such as DCT on the input reduced image, quantizes the generated orthogonal transform coefficient, and outputs it as a predicted image transform coefficient. The predicted image inverse quantization inverse transform unit 203 generates a locally decoded reduced image by performing inverse quantization and inverse orthogonal transform, which are the inverse processes of the predicted image transform quantization unit 202, on the input predicted image transform coefficient. Then output. In the predicted image enlarging unit 204, processing for improving the resolution is performed on the input locally decoded reduced image, the image is enlarged so as to have the same size as the macroblock image, and is output as the first intra predicted image. Here, for example, the processing content may be enlarged by interpolation processing, or the processing content is not particularly limited as long as it is a processing that improves the resolution of an input image by any other method.

In the above description, the case where the image is reduced to 4 × 4 pixels has been described. However, the image may be reduced to one pixel by the image reduction unit 201 and returned to the original size by the image enlargement unit 204. In this case, for example, the pixel at the lower right of the block can be a reduced image, and the same effect can be obtained by enlarging by enlarging by using a locally decoded image of the peripheral block at the time of enlargement. Further, the reduced image may be configured such that the pixel value is directly encoded without performing orthogonal transformation or quantization, or the difference value is encoded by DC prediction of the pixel value.

Next, the operation of image coding apparatus 100 according to the present embodiment will be described.
FIG. 2 is a flowchart showing processing of the image encoding device 100.
First, when a moving image is input to the image encoding device 100, the moving image is divided into macroblock units by the block dividing unit 101, and each divided macroblock image is output (step ST101). Next, intra-frame prediction is performed on each macroblock image in the first intra prediction unit 200, the first intra prediction image is output, and information on the prediction image is output as a prediction image transform coefficient (step) ST200). Next, when the macroblock image and the first intra prediction image are input to the original image difference calculation unit 102, a difference value is calculated and output as a difference macroblock image (step ST102). Next, the difference macroblock image is subjected to orthogonal transform such as DCT in the difference transform quantization unit 103, and the generated orthogonal transform coefficient is quantized and the quantized coefficient is output (step ST103). Further, the quantized coefficient and the predicted image transform coefficient are entropy encoded by the entropy encoding unit 104, and a bit stream is output (step ST104).

Next, details of step ST200 will be described.
First, the input macroblock image is reduced by the image reduction unit 201 and a reduced image is output (step ST201). The reduced image is subjected to orthogonal transform such as DCT in the predicted image transform quantization unit 202, and the generated orthogonal transform coefficient is quantized and output as a predicted image transform coefficient (step ST202). The predicted image transform coefficient is subjected to inverse quantization and inverse orthogonal transform, which are the inverse processes of step ST103, by the predicted image inverse quantization inverse transform unit 203, and a locally decoded reduced image is output (step ST203). When the local decoded reduced image is input to the predicted image enlarging unit 204, a process for improving the resolution is performed, and the local decoded reduced image is enlarged so as to have the same size as the macroblock image and is output as the first intra predicted image ( Step ST204).

As described above, the image encoding device 100 according to the present embodiment performs image reduction / transformation / quantization / inverse quantization / inverse transform / image enlargement when performing intra prediction, thereby A predicted image of a macroblock image that does not depend on the state of an edge can be generated, and the predicted image can be expressed with a quantized transform coefficient of a reduced image, so that the number of bits required to reproduce the predicted image can be reduced. . Therefore, stable intra-frame coding with high coding efficiency can be realized.

It should be noted that the components of each unit in the image encoding device 100 may be configured by hardware or software. Moreover, the module which combined hardware and software may be sufficient. The orthogonal transform process is not particularly limited, and DCT, DST (Discrete Sine Transform: Discrete Sine Transform), DFT (Discrete Fourier Transform: Discrete Fourier Transform), wavelet transform, integer transform process, and the like may be performed.

As described above, according to the image coding apparatus of Embodiment 1, one frame of image data is input, divided into a plurality of blocks, and a macroblock image is output, and a macroblock image is input. And generating a first intra prediction image and outputting first intra prediction data that is information for reconstructing the intra prediction image (first intra prediction portion (first intra prediction portion) ) 200, an original image difference calculation unit 102 that performs a difference calculation between the macroblock image and the first intra prediction image and outputs a difference image, and a difference transform quantization unit that frequency-converts and quantizes the difference image and outputs a transform coefficient 103, an entropy encoding unit 104 that entropy-encodes the first intra-screen prediction data and the transform coefficient, and outputs a bit stream, and includes a first intra prediction unit 200. An image reduction unit 201 that reduces a macroblock image and outputs a reduced image, a predictive image transform quantization unit 202 that frequency-converts and quantizes the reduced image and outputs first in-screen prediction data, and a first in-screen A predicted image inverse quantization inverse transform unit 203 that performs inverse quantization and inverse frequency transform on the prediction data and outputs a local decoded predicted image, and a predicted image enlargement unit that expands the local decoded predicted image and generates a first intra prediction image 204, the prediction can be performed stably and efficiently regardless of the texture of the input image, and the encoding efficiency can be improved.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing a configuration of the image encoding device 100a according to the second embodiment.
The image encoding device 100a is configured using a DC component prediction intra prediction unit 200a as a first intra prediction unit. Since the configuration other than this is the same as that of the image coding apparatus 100 according to the first embodiment, differences from the image coding apparatus 100 according to the first embodiment will be described below.

The DC component prediction intra prediction unit 200a differs only in that it includes a DC component prediction unit 205 and a DC component storage buffer 206 in addition to the configuration of the first intra prediction unit 200 in the first embodiment. The DC component prediction unit 205 outputs the DC component of the input predicted image transform coefficient to the DC component storage buffer 206 and reads the DC component of the adjacent block from the DC component storage buffer 206 to predict the DC component. A value is generated and subtracted from the DC component of the predicted image conversion coefficient to obtain a DC difference coefficient. Then, the obtained DC difference coefficient and other AC components are output to the entropy encoding unit 104 as a DC difference predicted image transform coefficient. The DC component storage buffer 206 is a buffer for storing the DC component of the predicted image conversion coefficient.

Next, the operation of the image coding apparatus 100a according to Embodiment 2 will be described.
FIG. 4 is a flowchart showing the operation of the image coding apparatus 100a according to the second embodiment. Note that during operation, the only difference from the first embodiment is the operation related to the DC component prediction intra prediction unit 200a (step ST200a), and therefore step ST200a will be described.
The processing up to the predicted image transform coefficient inverse quantization and inverse transform in step ST203 and the image enlargement process in step ST204 are the same as those in the first embodiment. When the predicted image transform coefficient output in step ST202 is input to the DC component prediction unit 205, only the DC component is first extracted and stored in the DC component storage buffer 206 (step ST211). Next, the DC component of the adjacent block is read from the DC component storage buffer 206, a predicted value of the DC component is generated, and subtracted from the DC component of the predicted image transform coefficient to obtain a DC difference coefficient. The obtained DC difference coefficient and other AC components are output to the entropy encoding unit 104 as DC difference predicted image transform coefficients (step ST212).

As described above, the image encoding device 100a according to Embodiment 2 is configured to predict the DC component of the predicted image transform coefficient from the DC component in the adjacent block, and to entropy encode the prediction residual. In general, since image data is highly correlated in the spatial direction, the amplitude of the DC component prediction residual is generally smaller than the DC component itself. Therefore, video coding with higher compression efficiency can be realized by performing entropy coding of the prediction residual of the DC component.

As described above, according to the image coding device 100a of the second embodiment, the DC component prediction intra prediction unit (first intra prediction unit) 200a is a DC component that is a direct current component of the first intra prediction data. A DC component storage buffer 206 that stores the component as a locally decoded DC component, and a predicted value of the DC component is calculated based on the local decoded DC component stored in the DC component storage buffer 206, and the first in-screen prediction data And a DC component prediction unit 205 that outputs the first intra prediction data difference value after subtracting the prediction value from the DC component, and the entropy encoding unit 104 uses the first intra prediction data instead of the first intra prediction data. Since the intra-screen prediction data difference value is entropy-encoded, video encoding with higher compression efficiency can be realized.

Embodiment 3 FIG.
FIG. 5 is a block diagram illustrating a configuration of the image encoding device 100b according to the third embodiment.
The image encoding device 100b is configured using an average pixel prediction intra prediction unit 200b as a first intra-screen prediction unit, and further includes a difference inverse quantization inverse transform unit 105, a difference image addition unit 106, a frame memory. 107. Since the configuration other than this is the same as the configuration of the first embodiment shown in FIG. 1, only the differences will be described.

The difference inverse quantization inverse transform unit 105 performs inverse quantization and inverse orthogonal transform, which are inverse processes of the difference transform quantization unit 103, on the quantization coefficient output from the difference transform quantization unit 103, and performs local decoding difference Output an image. The difference image adding unit 106 generates and outputs a locally decoded image by adding the locally decoded difference image and the first intra predicted image. The frame memory 107 is a buffer for storing locally decoded images.

The average pixel prediction intra prediction unit 200b includes an average pixel value prediction unit 207, an average pixel value subtraction unit 208, and an average pixel value addition unit 209 in addition to the configuration of the first intra prediction unit 200 of the first embodiment. Only different. The average pixel value prediction unit 207 reads local decoded image data of the adjacent block from the frame memory 107, calculates the pixel average value of the adjacent block, and outputs it as the average pixel value. As an average pixel value of adjacent blocks, an average value of pixels adjacent to the upper and left sides may be used, or an average value obtained by adding the lowermost right pixel of the upper left block of the processing target block may be used. Alternatively, the average value of all the blocks adjacent to the upper and left sides may be used, or the average value of pixels located within a predetermined number of pixels near the processing target block may be used. In other words, the same effect can be obtained by any means as long as it is an average value of pixel values of locally decoded image data in the vicinity of the processing target block. The average pixel value subtracting unit 208 subtracts the average pixel value output from the average pixel value predicting unit 207 from each pixel value of the reduced image output from the image reducing unit 201 and converts the result into a predicted reduced image as a difference reduced image. The data is output to the quantization unit 202. The average pixel value adding unit 209 adds the average pixel value output from the average pixel value predicting unit 207 to the local decoded reduced image output from the predicted image inverse quantization inverse transform unit 203, and locally decodes the result. The reduced image is output to the predicted image enlargement unit 204.

Next, the operation of the image coding apparatus 100b according to Embodiment 3 will be described.
FIG. 6 is a flowchart showing the operation of the image coding apparatus 100b according to the third embodiment.
First, when a moving image is input to the image encoding device 100b, the moving image is divided into macroblock units by the block dividing unit 101, and each divided macroblock image is output (step ST101). Each macroblock image is subjected to intra-frame prediction in the average pixel prediction intra prediction unit 200b using local decoded image data of peripheral blocks stored in the frame memory 107, and a first intra prediction image is output. Information about the image is output as a predicted image conversion coefficient (step ST200b).

When the macroblock image and the first intra prediction image are input to the original image difference calculation unit 102, a difference value is calculated and output as a difference macroblock image (step ST102). The difference macroblock image is subjected to orthogonal transform such as DCT in the difference transform quantization unit 103, and the generated orthogonal transform coefficient is quantized and the quantized coefficient is output (step ST103). The quantized coefficient and the predicted image transform coefficient are entropy encoded by the entropy encoding unit 104, and a bit stream is output (step ST104). The quantized coefficient is subjected to inverse quantization and inverse orthogonal transform, which are inverse processes of the difference transform quantization unit 103, in the difference inverse quantization inverse transform unit 105, and is output as a locally decoded difference image (step ST111). This locally decoded difference image and the first intra predicted image generated in step ST200b are added by the difference image adding unit 106 and output as a locally decoded image (step ST112). The locally decoded image is stored in frame memory 107 (step ST113).

Next, details of step ST200b will be described. Note that steps ST201 to ST204 in step ST200b are the same processes as in the first and second embodiments.
First, the input macroblock image is reduced by the image reduction unit 201 and a reduced image is output (step ST201). On the other hand, the average pixel value predicting unit 207 reads the locally decoded image data of the adjacent block from the frame memory 107, calculates the pixel average value of the adjacent block, and outputs it as an average pixel value (step ST221). The average pixel value subtracting unit 208 subtracts the average pixel value from each pixel value of the reduced image, and outputs the result as a difference reduced image to the predicted image transform quantization unit 202 (step ST222). The difference reduced image is subjected to orthogonal transform such as DCT in the predicted image transform quantization unit 202, and the generated orthogonal transform coefficient is quantized and output as a predicted image transform coefficient (step ST202). The predicted image transform coefficient is subjected to inverse quantization and inverse orthogonal transform, which are the inverse processes of step ST202, by the predicted image inverse quantization inverse transform unit 203, and a locally decoded difference reduced image is output (step ST203). The average pixel value is added to the local decoded difference reduced image by the average pixel value adding unit 209 and output as a locally decoded reduced image (step ST223). When the local decoded reduced image is input to the predicted image enlarging unit 204, a process for improving the resolution is performed, and the local decoded reduced image is enlarged so as to have the same size as the macroblock image and is output as the first intra predicted image (step). ST204).

As described above, the image encoding device 100b according to Embodiment 3 is configured to predict each pixel value of the reduced image from the average value of the pixel values in the adjacent blocks, and to convert and quantize the prediction residual. . In general, since image data is highly correlated in the spatial direction, the energy of the prediction residual signal is smaller than that of the signal before prediction, and the entropy of the quantized transform coefficient is also reduced. Therefore, by performing entropy coding of the signal obtained in this way, video coding with higher compression efficiency can be realized. In the third embodiment, the average pixel value is subtracted from each pixel value of the reduced image. However, the same applies to the case where the processing order is changed and a reduced image is generated after subtracting the average pixel value from the macroblock image. The effect is obtained. In this case, instead of adding the average pixel value to the locally decoded reduced image, encoding can be suitably performed by adding the average pixel value after enlarging the locally decoded reduced image by the predicted image enlarging unit 204.

As described above, according to the image encoding device 100b of the third embodiment, the difference inverse quantization inverse transform unit 105 that inputs a transform coefficient, performs inverse quantization and inverse frequency transform, and outputs a difference local decoded image; A difference image addition unit 106 that adds the first intra-screen prediction image and the difference local decoded image and outputs a local decoded image; and a frame memory 107 that stores the local decoded image, and includes an average pixel prediction intra prediction unit (first 200b) predicts the average value of the pixel values of the processing target area from the pixel values of the peripheral area of the processing target area using the locally decoded image stored in the frame memory 107, and uses the predicted value as the predicted average pixel value. An average pixel value predicting unit 207 for outputting, an average pixel value subtracting unit 208 for subtracting the predicted average pixel value from each pixel value of the reduced image and outputting an average value removed reduced image, and a predicted image inverse quantization inverse transform An average pixel value adding unit 209 that adds the output of 203 and the predicted average pixel value and outputs a locally decoded predicted image, and the predicted image transform quantization unit 202 performs frequency conversion and quantization on the average value removed reduced image. In addition to outputting the first intra-screen prediction data, the predicted image inverse quantization inverse transform unit 203 performs inverse quantization and inverse frequency transform on the first intra-screen prediction data and outputs the result as an average-value-removed local decoded predicted image. Therefore, video encoding with higher compression efficiency can be realized.

Embodiment 4 FIG.
FIG. 7 is a block diagram illustrating a configuration of an image encoding device 100c according to the fourth embodiment.
In addition to the average pixel prediction intra prediction unit 200b in the image encoding device 100b of the third embodiment described above, the image encoding device 100c also performs intra prediction on the second intra prediction unit (second intra prediction unit) 108. It has functions that can be selected as means. Since the configuration of the average pixel prediction intra prediction unit 200b is the same as that of the third embodiment, a configuration different from this will be described below.

The second intra prediction unit 108 is, for example, a conventional H.264 standard. As in intra prediction in H.264, the pixel values of the encoded peripheral blocks are expanded to generate and output a second intra predicted image, and information such as the prediction direction is input to the entropy encoding unit 104 as an intra prediction mode. Output. The intra prediction switching switch (predicted image selection unit) 109 compares the input first intra predicted image and second intra predicted image with the macroblock image, selects the one with higher prediction efficiency, and sets it as the intra predicted image. In addition to outputting, a flag indicating which prediction image has been selected is output to the entropy encoding unit 104 as intra prediction type information.

Next, the operation of the image coding apparatus 100c according to the fourth embodiment will be described.
FIG. 8 is a flowchart showing the operation of the image coding apparatus 100c according to the fourth embodiment. Since the operations of step ST101, step ST200b, steps ST102 to ST104, and steps ST111 to ST113 are the same as those in the third embodiment, the description of these processes is omitted.

When the macroblock image output from the block dividing unit 101 is input to the second intra prediction unit 108, the second intra prediction unit 108, for example, uses conventional H.264. Intra prediction in H.264 is performed, a second intra predicted image is output, and information such as a prediction direction is output to the entropy encoding unit 104 as an intra prediction mode (step ST121). When the first and second intra prediction images are generated, the intra prediction changeover switch 109 compares the input prediction image with the macroblock image, and selects the one with the higher prediction efficiency and outputs it as the intra prediction image. In addition, a flag indicating which prediction image has been selected is output to the entropy encoding unit 104 as intra prediction type information (step ST122). As intra prediction type information, the first intra prediction unit may be defined as one of a plurality of intra prediction types as shown in FIG. 21, or the first intra prediction unit and the second intra prediction type as shown in FIG. A flag for identifying the intra prediction unit may be defined.

As described above, in the image coding device 100c according to Embodiment 4, in addition to the average pixel prediction intra prediction, the intra prediction based on the conventional peripheral pixel expansion can be selected. Video coding with higher compression efficiency because it can be predicted more effectively by intra prediction using peripheral pixel expansion with good prediction efficiency, and can be effectively predicted by average pixel prediction intra prediction for other edges. Can be realized.

As described above, according to the image encoding device 100c of the fourth embodiment, the pixel value of the processing target region is predicted from the pixel value of the peripheral region of the processing target region using the local decoded image stored in the frame memory 107. The second intra prediction unit (second intra prediction unit) 108 that outputs the second intra prediction image and outputs information for reconstructing the prediction image as the second intra prediction data. And comparing the first intra-screen prediction image and the second intra-screen prediction image, selecting a prediction image with high prediction efficiency, outputting it as the intra-screen prediction image, and indicating which prediction image was selected An intra-prediction switching switch (prediction image selection unit) 109 that outputs the prediction type information, and the entropy encoding unit 104 entropy encodes the second intra-screen prediction data and the prediction type information. Since the way, it is possible to realize a higher compression efficiency video encoding.

Embodiment 5 FIG.
FIG. 9 is a block diagram showing a configuration of an image encoding device 100d according to the fifth embodiment.
The image encoding device 100d according to the fifth embodiment includes a switching intra prediction unit 200c as a first intra-screen prediction unit. The switching intra prediction unit 200c includes a DC component prediction unit 205 and a DC component storage buffer 206 in the second embodiment in addition to the configuration of the average pixel prediction intra prediction unit 200b in the fourth embodiment. Since other configurations are the same as those of the fourth embodiment, the same reference numerals are given to corresponding portions, and descriptions thereof are omitted.

Next, the operation of the image encoding device 100d according to the fifth embodiment will be described.
FIG. 10 is a flowchart showing the operation of the image encoding device 100d according to the fifth embodiment. Since only the process of step ST200c is different from the fourth embodiment, only the different process will be described.
When the predicted image transform coefficient output in the predicted image transform / quantization process in step ST202 is input to the DC component prediction unit 205, only the DC component is first extracted and stored in the DC component storage buffer 206 (step ST211). ). Next, the DC component of the adjacent block is read from the DC component storage buffer 206, a predicted value of the DC component is generated, and subtracted from the DC component of the predicted image transform coefficient to obtain a DC difference coefficient. The obtained DC difference coefficient and other AC components are output to the entropy encoding unit 104 as DC difference predicted image transform coefficients (step ST212).

As described above, the image coding device 100d according to Embodiment 5 performs average pixel value prediction when the second intra prediction is selected, and performs DC component prediction when the switched intra prediction is selected. By suppressing the entropy of the coefficient generated by this, video encoding with higher compression efficiency can be realized.

In the fifth embodiment, the configurations of the DC component prediction unit 205 and the DC component storage buffer 206 are applied to the configuration of the fourth embodiment, but may be applied to the configuration of the third embodiment.

As described above, according to the image coding device 100d of the fifth embodiment, in addition to the configuration of the fourth embodiment, the switching intra prediction unit (first intra-screen prediction unit) 200c A DC component storage buffer 206 for storing a DC component, which is a direct current component of the prediction data, as a locally decoded DC component; and a predicted value of the DC component based on the locally decoded DC component stored in the DC component storage buffer 206; The entropy encoding unit 104 includes a DC component prediction unit 205 that outputs a first intra prediction data difference value after subtracting the prediction value from the DC component of the first intra prediction data. Since the first intra prediction data difference value is entropy encoded instead of the intra prediction data, video encoding with higher compression efficiency can be realized.

Embodiment 6 FIG.
Embodiments 6 to 10 relate to an image decoding apparatus corresponding to the image encoding apparatuses of Embodiments 1 to 5.
FIG. 11 is a block diagram illustrating a configuration of the image decoding apparatus 300 according to the sixth embodiment.
The image decoding apparatus 300 includes an entropy decoding unit 301, a difference inverse quantization inverse transform unit 302, a first predicted image generation unit (first in-screen predicted image generation unit) 400, and a difference image addition unit 303. Is done.
The entropy decoding unit 301 performs entropy decoding on the input bitstream and outputs the resulting predicted image transform coefficient and quantization coefficient. The difference inverse quantization inverse transform unit 302 performs inverse quantization and inverse orthogonal transform, which are inverse processes of the difference transform quantization unit 103 in the image coding apparatus, on the quantized coefficient, and outputs a locally decoded difference image. The first predicted image generation unit 400 generates a predicted image based on the input predicted image conversion coefficient and outputs it as a first intra predicted image. The difference image addition unit 303 adds the locally decoded difference image and the first intra-predicted image and outputs the result as a decoded image.

More specifically, the first predicted image generation unit 400 includes a predicted image inverse quantization inverse transform unit 401 and a predicted image enlargement unit 402. The predicted image inverse quantization inverse transform unit 401 generates a locally decoded reduced image by performing inverse quantization and inverse orthogonal transform, which are inverse processes of the predicted image transform quantization unit 202, on the input predicted image transform coefficient. And output. The predicted image enlarging unit 402 performs processing for improving the resolution of the input local decoded reduced image, enlarges the image to have the same size as the macroblock image, and outputs the first intra predicted image.

Next, the operation of the image decoding apparatus 300 according to Embodiment 6 will be described.
FIG. 12 is a flowchart showing processing of the image decoding apparatus 300 according to Embodiment 6.
First, when a bit stream is input to the image decoding apparatus 300, the bit stream is entropy-decoded by the entropy decoding unit 301, and as a result, a predicted image transform coefficient and a quantization coefficient are output (step ST301). The quantized coefficient is subjected to inverse quantization and inverse transform processing in the difference inverse quantization inverse transform unit 302, and a local decoded difference image is output (step ST302). On the other hand, when the predicted image conversion coefficient is input to the first predicted image generation unit 400, a predicted image is generated and output as the first intra predicted image (step ST400). The locally decoded differential image and the first intra predicted image obtained in this way are added by the differential image adding unit 303 and output as a decoded image (step ST303).

In step ST400, more specifically, the input predicted image transform coefficient is subjected to inverse quantization and inverse transform processing in the predicted image inverse quantization inverse transform unit 401, and as a result, a locally decoded reduced image is output ( Step ST401). The local decoded reduced image is subjected to processing for improving the resolution in the predicted image enlarging unit 402, and is output as a first intra predicted image (step ST402).

As described above, the image decoding apparatus 300 according to Embodiment 6 is configured to perform the inverse process of the image encoding apparatus 100 according to Embodiment 1, and thus is generated by the image encoding apparatus 100 according to Embodiment 1. The decoded bit stream can be suitably decoded to obtain a decoded image. In addition, since the local decoded image is not used for predictive image generation, a reduced image can be generated without generating a decoded image, and a thumbnail image or the like can be generated with a small amount of calculation.

As described above, according to the image decoding apparatus 300 of the sixth embodiment, the entropy decoding unit 301 that entropy-decodes the bitstream and outputs the transform coefficient and the first in-screen prediction data, and the transform coefficient is dequantized and dequantized. A differential inverse quantization inverse transform unit 302 that performs inverse frequency transform and outputs a differential decoded image, and a first predicted image generation unit that reconstructs and outputs the first intra prediction image based on the first intra prediction data (First intra prediction image generation unit) 400, and a difference image addition unit 303 that adds the differential decoded image and the first intra prediction image and outputs a decoded image, and includes the first intra prediction image. The generation unit 400 performs inverse quantization and inverse frequency conversion on the first intra prediction data and outputs a decoded prediction image, and expands the decoded prediction image to generate the first intra prediction. Generate image Since a prediction image enlargement unit 402, it can be decoded efficiently coded video bit stream, and can be produced with a smaller amount of calculation and thumbnail images.

Embodiment 7 FIG.
FIG. 13 is a block diagram illustrating a configuration of an image decoding device 300a according to the seventh embodiment.
The image decoding apparatus 300a includes a DC component prediction intra-prediction image generation unit 400a as a first intra-screen prediction image generation unit. This DC component prediction intra-prediction image generation unit 400a replaces the first prediction image generation unit 400 of the sixth embodiment. In addition to the prediction image inverse quantization inverse transformation unit 401 and the prediction image enlargement unit 402, the DC component prediction intra prediction image generation unit 400a A component prediction unit 403 and a DC component storage buffer 404 are provided. The DC component prediction unit 403 reads the stored DC component of the adjacent block from the DC component storage buffer 404, generates a predicted value of the DC component, adds it to the DC component of the predicted image transform coefficient, and obtains the DC coefficient. . The obtained DC coefficients and other AC components are output as predicted image transform coefficients to the predicted image inverse quantization inverse transform unit 401 and the DC coefficients are stored in the DC component storage buffer 404. The DC component storage buffer 404 is a buffer for storing the DC component of the predicted image conversion coefficient.

Next, processing of the image decoding device 300a according to Embodiment 7 will be described.
FIG. 14 is a flowchart showing the operation of the image decoding apparatus 300a according to the seventh embodiment.
Since the difference between the seventh embodiment and the sixth embodiment is only the process related to the first predicted image generation unit 400 (step ST400a), only step ST400a will be described.
When the predicted image transform coefficient output in step ST301 is input to the DC component prediction unit 403, first, the DC component of the adjacent block is read from the DC component storage buffer 404, and a predicted value of the DC component is generated. A DC coefficient is obtained by adding the DC component of the predicted image conversion coefficient. The obtained DC coefficients and other AC components are output to the predicted image inverse quantization inverse transform unit 401 as predicted image transform coefficients (step ST411). The obtained DC coefficient is stored in the DC component storage buffer 404 (step ST412). Subsequent steps ST401 and ST402 are the same as in the sixth embodiment.

As described above, the image decoding device 300a according to the seventh embodiment is configured to perform the inverse process of the image coding device 100a according to the second embodiment, and thus is generated by the image coding device 100a according to the second embodiment. The decoded bit stream can be suitably decoded to obtain a decoded image.

As described above, according to the image decoding apparatus 300a of the seventh embodiment, the DC component prediction intra prediction image generation unit (first intra prediction image generation unit) 400a predicts the DC component based on the decoded DC component. A DC component prediction unit 403 that calculates a value, adds the predicted value to the DC component of the first intra-screen prediction data difference value, and then outputs the first intra-screen prediction data; A DC component storage buffer 404 that stores a DC component that is a direct current component as a decoded DC component, and the entropy decoding unit 301 entropy decodes the first intra prediction data difference value instead of the first intra prediction data. As a result, the encoded image bitstream can be efficiently decoded and a decoded image can be obtained.

Embodiment 8 FIG.
FIG. 15 is a block diagram illustrating a configuration of an image decoding device 300b according to the eighth embodiment.
The image decoding apparatus 300b is configured using an average pixel prediction intra-prediction image generation unit 400b as a first intra-screen prediction image generation unit, and further includes a frame memory 304. Other configurations are the same as those in the sixth and seventh embodiments.

The frame memory 304 is a buffer for storing the decoded image. The average pixel prediction intra prediction image generation unit 400b includes an average pixel value prediction unit 405 and an average pixel value addition unit 406 in addition to the configuration of the first prediction image generation unit 400 in the sixth embodiment. The average pixel value prediction unit 405 reads the decoded image data of the adjacent block from the frame memory 304, calculates the pixel average value of the adjacent block, and outputs it as the average pixel value. The average pixel value addition unit 406 adds the average pixel value output from the average pixel value prediction unit 405 to the local decoded reduced image output from the predicted image inverse quantization inverse conversion unit 401, and the result is locally decoded. The reduced image is output to the predicted image enlargement unit 402. Naturally, when the encoding device is configured to add the average pixel value after enlarging the locally decoded reduced image by the predicted image enlargement unit, the decoding device can also suitably decode by performing decoding processing in the same order. Become.

Next, processing of the image decoding device 300b according to Embodiment 8 will be described.
FIG. 16 is a flowchart showing processing of the image decoding device 300b according to Embodiment 8.
First, when a bit stream is input to the image decoding device 300b, the bit stream is entropy-decoded by the entropy decoding unit 301, and as a result, a predicted image transform coefficient and a quantization coefficient are output (step ST301). The quantized coefficient is subjected to inverse quantization and inverse transform processing in the difference inverse quantization inverse transform unit 302, and a local decoded difference image is output (step ST302). On the other hand, when the predicted image transform coefficient is input to the average pixel predicted intra predicted image generation unit 400b, a predicted image is generated based on the decoded image stored in the frame memory 304, and is output as the first intra predicted image. (Step ST400b). The locally decoded differential image and the first intra predicted image obtained in this way are added by the differential image adding unit 303 and output as a decoded image (step ST303). The decoded image is stored in the frame memory 304 and used for intra prediction image generation (step ST311).

In step ST400b, more specifically, the input predicted image transform coefficient is subjected to inverse quantization and inverse transform processing in the predicted image inverse quantization inverse transform unit 401, and as a result, a locally decoded reduced image is output (step ST400b). ST401). On the other hand, the pixel value data of the decoded peripheral blocks is input to the average pixel value prediction unit 405, and the average value thereof is calculated and output as an average pixel value (step ST421). The average pixel value and the locally decoded reduced image are added by the average pixel value adding unit 406, and a locally decoded reduced image is output (step ST422). The local decoded reduced image is subjected to processing for improving the resolution in the predicted image enlarging unit 402, and is output as a first intra predicted image (step ST402).

As described above, the image decoding device 300b according to the eighth embodiment is configured to perform the reverse process of the image coding device 100b according to the third embodiment, and thus is generated by the image coding device 100b according to the third embodiment. The decoded bit stream can be suitably decoded to obtain a decoded image.

As described above, according to the image decoding apparatus 300b of the eighth embodiment, the frame memory 304 that stores the decoded image is provided, and the average pixel prediction intra prediction image generation unit (first intra prediction image generation unit) 400b is provided. An average pixel value prediction unit 405 that predicts an average value of the pixel values of the processing target area from the pixel values of the peripheral area of the processing target area using the decoded image stored in the frame memory 304, and outputs the predicted average pixel value; The predicted image inverse quantization inverse transform unit 401 includes an average pixel value addition unit 406 that adds the output of the predicted image inverse quantization inverse transform unit 401 and the predicted average pixel value and outputs a decoded predicted image. Intra-screen prediction data is inversely quantized and inverse frequency converted and an average-value-removed decoded prediction image is output, so that the encoded image bitstream can be efficiently decoded to obtain a decoded image. Kill.

Embodiment 9 FIG.
FIG. 17 is a block diagram illustrating a configuration of an image decoding device 300c according to the ninth embodiment.
In addition to the average pixel prediction intra-prediction image generation unit 400b in the image decoding device 300b of the eighth embodiment described above, the image decoding device 300c includes a second prediction image generation unit (second intra-screen prediction image generation unit) 305. Is also provided with a function that can be selected as an intra predicted image generating means. Since the configuration of the average pixel prediction intra predicted image generation unit 400b is the same as that of the eighth embodiment, a configuration different from this will be described below.

The second predicted image generation unit 305 obtains information such as a prediction direction based on the intra prediction mode entropy-decoded by the entropy decoding unit 301, for example. A second intra-predicted image is generated and output by expanding the pixel values of the encoded peripheral blocks as in the case of intra prediction in H.264. The intra prediction changeover switch (prediction image selection unit) 306 indicates a flag indicating which prediction image entropy-decoded by the entropy decoding unit 301 is selected from the input first intra prediction image and second intra prediction image. Is selected based on the intra prediction type information, and is output as an intra predicted image.

Next, the operation of the image decoding device 300c according to the ninth embodiment will be described.
FIG. 18 is a flowchart illustrating the operation of the image decoding device 300c according to the ninth embodiment.
This means that intra prediction type information, which is a flag indicating which prediction image has been selected as entropy-decoded information, is input to the intra prediction changeover switch 306, and the intra prediction type information selects the second intra prediction image. If so, the second intra prediction image generation is performed, and if not, the switching process is performed so that the average pixel prediction intra prediction image generation is performed (step ST321).

Based on the intra prediction mode entropy decoded by the entropy decoding unit 301, the second predicted image generation unit 305 obtains information such as the prediction direction. A second intra-prediction image is generated and output by expanding the pixel values of the encoded peripheral blocks as in the case of intra prediction in H.264 (step ST322). Since other operations are the same as those in the eighth embodiment, description thereof is omitted here.

As described above, the image decoding device 300c according to the ninth embodiment is configured to perform the reverse process of the image coding device 100c according to the fourth embodiment, and thus generated by the image coding device 100c according to the fourth embodiment. The decoded bit stream can be suitably decoded to obtain a decoded image.

As described above, according to the image decoding device 300c of the ninth embodiment, the entropy decoding unit 301 performs entropy decoding on the second intra prediction data and the prediction type information, and based on the second intra prediction data. A second predicted image generation unit that predicts the pixel value of the processing target region from the pixel value of the peripheral region of the processing target region using the decoded image stored in the frame memory 304 and outputs a second intra prediction image ( A second intra prediction image generation unit) 305 and an intra prediction changeover switch (prediction) that selects and outputs one of the first intra prediction image and the second intra prediction image based on the prediction type information. Image selection unit) 306, the encoded image bitstream can be efficiently decoded to obtain a decoded image.

Embodiment 10 FIG.
FIG. 19 is a block diagram illustrating a configuration of an image decoding device 300d according to the tenth embodiment.
The image decoding device 300d according to the tenth embodiment includes a switching intra predicted image generation unit 400c as the first intra prediction image generation unit. The switched intra predicted image generation unit 400c includes a DC component prediction unit 403 and a DC component storage buffer 404 in the seventh embodiment in addition to the configuration of the average pixel prediction intra predicted image generation unit 400b in the ninth embodiment. Is. Since other configurations are the same as those of the ninth embodiment, the same reference numerals are given to corresponding portions, and descriptions thereof are omitted.

Next, the operation of the image decoding device 300d according to the tenth embodiment will be described.
FIG. 20 is a flowchart illustrating the operation of the image decoding device 300d according to the tenth embodiment. Since only the process of step ST400c is different from the ninth embodiment, only the different process will be described.
When the predicted image transform coefficient output in step ST301 is input to the DC component prediction unit 403, first, the DC component of the adjacent block is read from the DC component storage buffer 404, and a predicted value of the DC component is generated. A DC coefficient is obtained by adding the DC component of the predicted image conversion coefficient. The obtained DC coefficients and other AC components are output to the predicted image inverse quantization inverse transform unit 401 as predicted image transform coefficients (step ST411). The obtained DC coefficient is stored in the DC component storage buffer 404 (step ST412). Other processes are the same as those in the ninth embodiment.

As described above, the image decoding device 300d according to the tenth embodiment is configured to perform the reverse process of the image coding device 100d according to the fifth embodiment, and thus generated by the image coding device 100d according to the fifth embodiment. The decoded bit stream can be suitably decoded to obtain a decoded image.

In the tenth embodiment, the configurations of the DC component prediction unit 403 and the DC component storage buffer 404 are applied to the configuration of the ninth embodiment, but may be applied to the configuration of the eighth embodiment.

As described above, according to the image decoding apparatus of the tenth embodiment, in addition to the configuration of the ninth embodiment, the switching intra-predicted image generation unit (first intra-screen predicted image generation unit) 400c includes the decoded DC component. A DC component prediction unit 403 that calculates a predicted value of a DC component based on the first component, adds the predicted value to the DC component of the first in-screen predicted data difference value, and outputs the first predicted value in the screen. A DC component storage buffer 404 that stores a DC component that is a direct current component of one intra-screen prediction data as a decoded DC component, and the entropy decoding unit 301 uses the first intra-screen prediction data instead of the first intra-screen prediction data. Since the prediction data difference value is output as the entropy decoding result, the encoded image bitstream can be efficiently decoded and a decoded image can be obtained.

As described above, the image encoding device and the image decoding device according to the present invention perform intra-screen prediction when an image is compressed and transmitted, and decode compressed data. H. It is suitable for encoding and decoding when the H.264 encoding method is used.

Claims

A block dividing unit that inputs image data of one frame, divides it into a plurality of blocks, and outputs a macroblock image;
A first intra prediction unit that inputs the macroblock image, generates a first intra prediction image, and outputs first intra prediction data that is information for reconstructing the intra prediction image; ,
A difference image generation unit that performs a difference calculation between the macroblock image and the first intra prediction image and outputs a difference image;
A difference transform quantizing unit for frequency transforming and quantizing the difference image and outputting transform coefficients;
An entropy encoding unit that entropy-encodes the first intra-screen prediction data and the transform coefficient and outputs a bitstream;
The first in-screen prediction unit
An image reduction unit that reduces the macroblock image and outputs a reduced image;
A predicted image transform quantization unit that frequency-converts and quantizes the reduced image and outputs first in-screen prediction data;
A predicted image inverse quantization transform unit that performs inverse quantization and inverse frequency transform on the first intra prediction data and outputs a locally decoded predicted image;
An image encoding apparatus comprising: a predicted image enlarging unit that expands the locally decoded predicted image to generate a first intra-screen predicted image.
A differential inverse quantization inverse transform unit that inputs a transform coefficient, performs inverse quantization and inverse frequency transform, and outputs a differential local decoded image;
A difference local decoding addition unit that adds a first intra prediction image and the difference local decoded image and outputs a local decoded image;
A frame memory for storing the locally decoded image;
The first in-screen predictor
An average pixel value prediction unit that predicts an average value of pixel values of the processing target region from pixel values of a peripheral region of the processing target region using the locally decoded image stored in the frame memory, and outputs the predicted average pixel value When,
An average value removing unit that subtracts the predicted average pixel value from each pixel value of the reduced image and outputs an average value removed reduced image; and
An output of a predicted image inverse quantization inverse transform unit and an average value adding unit that adds the predicted average pixel value and outputs a locally decoded predicted image;
And,
The predicted image transform quantization unit frequency-converts and quantizes the average-value-reduced reduced image and outputs first intra-screen prediction data, and the predicted image inverse quantization inverse transform unit includes the first intra-screen prediction data. The image coding apparatus according to claim 1, wherein the image is subjected to inverse quantization and inverse frequency conversion, and output as an average-value-removed local decoded prediction image.
Using the locally decoded image stored in the frame memory, the pixel value of the processing target region is predicted from the pixel value of the peripheral region of the processing target region, and the second intra prediction image is output and the prediction image is reconstructed A second in-screen prediction unit that outputs information for performing as second in-screen prediction data;
The first in-screen prediction image and the second in-screen prediction image are compared, a prediction image with high prediction efficiency is selected, output as the in-screen prediction image, and a prediction indicating which prediction image has been selected A predictive image selection unit that outputs type information,
The image encoding apparatus according to claim 2, wherein the entropy encoding unit performs entropy encoding on the second intra-screen prediction data and the prediction type information.
The first in-screen predictor
A DC component storage buffer for storing a DC component which is a direct current component of the first intra prediction data as a locally decoded DC component;
After calculating the predicted value of the DC component based on the locally decoded DC component stored in the DC component storage buffer and subtracting the predicted value from the DC component of the first intra-screen prediction data, the first intra-screen prediction data A DC component prediction unit that outputs the difference value,
The image encoding apparatus according to claim 1, wherein the entropy encoding unit performs entropy encoding on the first intra prediction data difference value instead of the first intra prediction data.
An entropy decoding unit that entropy decodes the bitstream and outputs transform coefficients and first intra prediction data;
A differential inverse quantization inverse transform unit that performs inverse quantization and inverse frequency transform on the transform coefficient and outputs a differential decoded image;
A first intra-screen prediction image generating unit that reconstructs and outputs a first intra-screen prediction image based on the first intra-screen prediction data;
A difference decoded image adding unit that adds the difference decoded image and the first intra prediction image and outputs a decoded image;
The first in-screen predicted image generation unit
A predicted image inverse quantization inverse transform unit for inversely quantizing and inverse frequency transforming the first intra-screen prediction data and outputting a decoded predicted image;
An image decoding apparatus comprising: a prediction image enlargement unit that enlarges the decoded prediction image and generates the first intra-screen prediction image.
A frame memory for storing the decoded image;
The first in-screen predicted image generation unit
An average pixel value prediction unit that predicts an average value of the pixel values of the processing target region from the pixel values of the peripheral region of the processing target region using the decoded image stored in the frame memory, and outputs the predicted average pixel value;
An average value adding unit that adds the output of the predicted image inverse quantization inverse transform unit and the predicted average pixel value and outputs a decoded predicted image;
6. The image decoding apparatus according to claim 5, wherein the predicted image inverse quantization transform unit performs inverse quantization and inverse frequency transform on the first intra prediction data, and outputs an average-value-removed decoded predicted image.
The entropy decoding unit entropy decodes the second intra prediction data and the prediction type information,
Using the decoded image stored in the frame memory based on the second intra-screen prediction data, the pixel value of the processing target region is predicted from the pixel value of the peripheral region of the processing target region, and the second intra-screen prediction image is obtained. A second in-screen predicted image generator to output;
The prediction image selection part which selects and outputs any one of the 1st prediction image in a screen and the prediction image in a 2nd screen based on the said prediction type information, The output of Claim 6 characterized by the above-mentioned. Image decoding device.
The first in-screen predicted image generation unit
A DC component prediction unit that calculates a predicted value of the DC component based on the decoded DC component, adds the predicted value to the DC component of the first intra-screen prediction data difference value, and then outputs the first intra-screen prediction data. ,
A DC component storage buffer that stores, as the decoded DC component, a DC component that is a direct current component of the first intra-screen prediction data,
6. The image decoding apparatus according to claim 5, wherein the entropy decoding unit outputs the first intra prediction data difference value as an entropy decoding result instead of the first intra prediction data.