JPH1141605A - Image coder and image detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image coder and image decode in which undesired consumption of memory capacity is prevented in the case of not using a reference image. SOLUTION: In the case that a memory output means 104 outputs a reference image, a coding section 101 substrates an input image from a reference image to generate a bit row and it is fed to an image decoder and also to a local decoding part 102. The local decoding part 102 adds the bit row to the reference image to generate the reference image. On the contrary, in the case that the memory output means 104 outputs no reference image, the input image and the reference image are not substrated but a bit row is generated and outputted, but no reference image is generated. In the case of processing a succeeding input image and the memory output means 104 outputs a reference image, the frame memory 103 stores the reference image in precedence over the output. In the case that no reference image is outputted on the contrary, a memory delete means 106 deletes contents of the frame memory 103. The above control is conducted by a coding control section 107.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding device for encoding an image to generate a bit sequence, and an image decoding device for inputting and decoding a bit sequence generated by encoding the image to generate a decoded image. It is.

[0002]

2. Description of the Related Art A typical method for encoding an image is an inter-frame difference encoding method. This generally involves subtracting an input image from the immediately preceding image and encoding only the difference information to generate a bit string. In a general conventional image encoding device using such an inter-frame differential encoding method, after encoding a current input image, when encoding the next input image, subtraction from the current image is performed. In order to make this possible, a reference image is generated by adding a bit sequence generated by encoding the current input image to the immediately preceding image and performing local decoding, thereby storing the reference image in the frame memory. , When encoding the next input image.

[0003] There is also an inter-frame difference encoding system in which an input image is subtracted from an immediately preceding image or an earlier image. In a conventional image encoding apparatus using such an inter-frame differential encoding method, after encoding a current input image, when encoding the next input image, subtraction from an arbitrary reference image is performed. In order to enable this, a plurality of reference images currently or previously generated are stored in the frame memory, and one reference image to be used when encoding the next input image is selected and output. I was

[0004] On the other hand, as described above, an input image is subtracted from the immediately preceding image, and only the difference information is coded to generate a bit string, and the image is formed using a typical inter-frame difference coding method. There is an inter-frame difference decoding method for decoding a bit sequence generated by encoding a coded image to generate a decoded image. In general, a difference image generated by decoding an input bit string is added to the immediately preceding image to generate a decoded image. In a general conventional image decoding apparatus using such an inter-frame differential decoding method, after decoding a current input bit sequence, it is possible to perform addition with a reference image when decoding a next input bit sequence. For this purpose, a reference image is generated by decoding a current input bit sequence, stored in a frame memory, and output when a next input bit sequence is decoded.

[0005] In addition, as described above, a bit string generated by encoding an image using an inter-frame differential encoding method in which an input image is subtracted from an immediately preceding image or an earlier image is encoded. In order to generate a decoded image by decoding, there is an inter-frame difference decoding method in which the difference information generated by decoding the input bit string is added to the immediately preceding image or the previous image. In a conventional image decoding apparatus using such an inter-frame differential decoding method, after decoding a current input bit sequence, it is possible to perform addition with an arbitrary reference image when decoding a next input bit sequence. Then, a plurality of reference images generated at present or before are stored in a frame memory, and one reference image used when decoding the next input bit string is selected and output.

[0006]

However, a general conventional image coding apparatus may not use a reference image when processing the next input image. Nevertheless, in the conventional image encoding device, when processing the current input image, the reference image is generated from the current input image and stored in the frame memory, so that the memory is unnecessarily consumed. Had the disadvantage that

Further, in a conventional image encoding apparatus which performs subtraction between an input image and an immediately preceding image or an earlier image, a current input image is processed when a next input image is processed. In some cases, only the reference image used at that time or a reference image after that is used. Nevertheless, in the conventional image encoding device, the reference image before the reference image used when processing the current input image may be stored in the frame memory, so that the memory is unnecessarily consumed. Had the disadvantage of doing so.

On the other hand, in a general conventional image decoding apparatus,
If the input bit sequence is generated without subtracting the input image from the immediately preceding image, similarly, the reference image is not used when processing the next input bit sequence. Nevertheless, in the conventional image decoding apparatus, when processing the current input bit string, the reference image is generated from the current input bit string and stored in the frame memory, so that the memory is unnecessarily consumed. Had the disadvantage that

In some cases, the input bit sequence is generated using only the reference image used in processing the current input bit sequence or a reference image thereafter. In such a case, in a conventional image decoding device that adds the difference information generated by decoding the input bit sequence to the immediately preceding image or the previous image, the next input bit sequence is similarly generated. At the time of processing, only the reference image used at the time of processing the current input bit string or a reference image thereafter is used. Nevertheless, in a conventional image decoding apparatus, a reference image prior to a reference image used in processing a current input bit string may be stored in a frame memory. Had the disadvantage of being

The present invention has been made in view of the above-mentioned drawbacks, and provides an image encoding apparatus and an image decoding apparatus capable of preventing unnecessary consumption of memory when a reference image is not used. That is the task.

[0011]

According to a first aspect of the present invention, there is provided an encoding section for subtracting an input image from a reference image to generate a bit string, A local decoding unit that newly adds the reference image to generate a reference image, a frame memory that stores the reference image, and a memory output unit that switches whether to output the reference image from the frame memory.
A memory input unit that switches the presence or absence of input of a reference image to the frame memory, a memory erasing unit that erases the frame memory, and a presence or absence of a reference image of the memory output unit. A control unit for controlling the memory input means and the memory erasing means based on the switching.

Further, in the second invention according to the present invention, an encoding unit for subtracting an input image from a reference image to generate a bit sequence, and adding a reference image to the bit sequence to newly generate a reference image A local decoding unit, a frame memory for storing a plurality of reference images, and a memory for selecting at most one output of the reference image from the frame memory from each reference image stored in the frame memory An image encoding device comprising: an output unit; a memory input unit that switches whether or not a reference image is input to the frame memory; and a memory erasure that erases the frame memory independently for each of the reference images. Means, and a control unit for controlling the memory input means and the memory erasing means based on selection of a reference image by the memory output means. And means.

As the memory input means in the first invention and the second invention, when the memory output means outputs the reference image from the frame memory, the reference image is output to the frame memory prior to the output. When the reference image is not output from the frame memory by the memory output means, it is preferable not to input the reference image to the frame memory.

As the memory erasing means in the first invention, it is preferable that when the memory output means does not output the reference image from the frame memory, the control section controls to erase the frame memory. . Further, as the memory erasing means in the second invention, when the memory output means outputs a reference image from the frame memory, a part of the frame memory storing the reference image preceding the output reference image is used. If the image is deleted and the reference image is not output from the frame memory by the memory output means,
It is preferable to control the control unit so that all parts of the frame memory are erased.

The image processing unit in the present invention is typically a frame unit. However, a processing unit is a unit of a small area of an image forming a frame or a group of pixels forming the small area. Optional.

In the image encoding apparatus according to the first aspect of the present invention, the memory input means switches whether or not a reference image is input to the frame memory, and the memory erasing means performs erasing of the frame memory. If the image is not output, the frame memory can be erased without inputting the reference image to the frame memory.
Prevent unnecessary consumption of memory.

In the image encoding apparatus according to the second aspect of the present invention, the memory input means switches whether or not a reference image is input to the frame memory, and erases the frame memory independently for each reference image. Means to output the reference image from the frame memory,
When the portion of the frame memory storing the reference image before the output reference image can be deleted, and when the reference image is not output from the frame memory,
Without inputting the reference image to the frame memory, it is possible to erase all the frame memory portions, thereby preventing unnecessary consumption of the memory.

On the other hand, in order to solve the above-mentioned problem, in a third invention according to the present invention, a decoding unit which adds a reference image to an input bit string to generate a decoded image and newly generates a reference image, What is claimed is: 1. An image decoding apparatus comprising: a frame memory for storing a reference image; and memory output means for switching whether or not the reference image is output from the frame memory. A memory input unit for switching the memory input unit, a memory erasing unit for erasing the frame memory, and a control unit for controlling the memory input unit and the memory erasing unit based on switching of the presence or absence of a reference image of the memory output unit. Means.

Further, in the fourth invention according to the present invention, a decoding unit which adds a reference image to an input bit string to generate a decoded image and newly generates a reference image, and stores a plurality of reference images. An image decoding apparatus comprising: a frame memory; and memory output means for selecting at most one output of the reference image from the frame memory from each reference image stored in the frame memory. Memory input means for switching the presence or absence of input of a reference image to a memory; memory erasing means for independently erasing the frame memory for each of the reference images; and A control unit for controlling the memory input means and the memory erasing means.

The memory input means in the third invention and the fourth invention may be arranged such that when the memory output means outputs the reference image from the frame memory, the reference image is output to the frame memory prior to the output. When the reference image is not output from the frame memory by the memory output means, it is preferable to control the control unit so as not to input the reference image to the frame memory.

As the memory erasing means in the third invention, it is preferable to erase the frame memory when the memory output means does not output the reference image from the frame memory. Further, as the memory erasing means in the fourth invention, when the memory output means outputs the reference image from the frame memory, a part of the frame memory storing the reference image preceding the output reference image is used. If the reference image is not output from the frame memory by the memory output means on the contrary, it is preferable to control the control unit so as to delete all parts of the frame memory.

The image processing unit in the present invention is typically a frame unit. However, a processing unit is a unit of a small area of an image forming a frame or a group of pixels forming the small area. Optional.

In the image decoding apparatus according to the third aspect of the present invention, the memory input means switches whether or not a reference image is input to the frame memory, and the memory erasing means performs erasing of the frame memory. Is not output, the frame memory can be erased without inputting the reference image to the frame memory, thereby preventing unnecessary consumption of the memory.

In the image decoding apparatus according to the fourth aspect of the present invention, the memory input means switches whether or not a reference image is input to the frame memory, and erases the frame memory independently for each reference image. When outputting the reference image from the frame memory,
When the portion of the frame memory storing the reference image before the output reference image can be deleted, and when the reference image is not output from the frame memory,
Without inputting the reference image to the frame memory, it is possible to erase all the frame memory portions, thereby preventing unnecessary consumption of the memory.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the first invention according to the present invention.

In the figure, reference numeral 101 denotes an encoding unit which subtracts an input image from a reference image to generate a bit sequence, 102 denotes a local decoding unit which adds the bit sequence to the reference image and newly generates a reference image, 103, a frame memory for storing the reference image; 104, a memory output unit for switching whether or not the reference image is output from the frame memory 103; 105, a memory input for switching whether or not a reference image is input to the frame memory 103; Means 106, a memory erasing means for erasing the frame memory 103; 107, an instruction to the memory output means 104 as to whether or not the reference image is output from the frame memory 103, and whether or not the reference image is input to the frame memory 103. To the memory input means 10
5 to delete the frame memory from the memory erasing means 1
An encoding control unit 108 instructed at 06 is an image decoding device that receives the bit string.

The operation of the first embodiment of the present invention will be described with reference to FIG.

When processing the current input image, the encoding control unit 107 instructs the memory output unit 104 whether or not a reference image is to be output from the frame memory 103, and outputs the reference image to the frame memory 103. It instructs the memory input means 105 to link the presence or absence of the input, and instructs the memory deletion means 106 to delete the frame memory 103 in conjunction with not outputting the reference image from the frame memory 103.

The current input image is encoded by
Is output from the memory output unit 1 according to an instruction from the encoding control unit 107.
When the reference image is output at 04, the pixel signal is subtracted from the reference image. Conversely, when the reference image is not output by the memory output unit 104 according to the instruction of the encoding control unit 107, nothing is performed. In this way, a bit string is generated.

The generated bit string is transmitted to the image decoding device 108
And input to the local decoding unit 102. When the memory output unit 104 outputs a reference image according to an instruction from the encoding control unit 107, the local decoding unit 102 adds a pixel signal to the reference image. Conversely, when the reference image is not output by the memory output unit 104 according to the instruction of the encoding control unit 107, nothing is performed. In this way, a new reference image is generated.

When processing the next input image, the frame memory 103 does not output the reference image by the memory output unit 104 according to the instruction of the encoding control unit 107, and the memory erasing unit according to the instruction of the encoding control unit 107. It is erased at 106. Conversely, when the reference image is output by the memory output unit 104 according to the instruction of the encoding control unit 107, the reference image is input and stored by the memory input unit 105 according to the instruction of the encoding control unit 107 prior to the output. deep.

As described above, when the memory output means 104 does not output the reference image from the frame memory 103 when processing the next input image, the memory input means 105
Thus, the present invention eliminates unnecessary consumption of memory in the image encoding apparatus by deleting the frame memory 103 by the memory erasing means 106 without inputting the reference image to the frame memory 103. It is possible to solve.

FIG. 2 is a diagram showing the configuration of an embodiment of the second invention according to the present invention.

In the figure, reference numeral 201 denotes an encoding unit for subtracting an input image from a reference image to generate a bit sequence, 202 denotes a local decoding unit for adding the bit sequence to the reference image and newly generating a reference image, 203 is a frame memory for storing a plurality of reference images, and 204 is a frame memory 203
A memory output unit that selects at most one of the reference images output from each of the reference images stored in the frame memory 203, a memory input unit 205 that switches whether or not the reference image is input to the frame memory 203, Reference numeral 206 denotes memory erasing means for independently erasing the frame memory 203 for each of the reference images. Reference numeral 207 denotes a memory output which selects at most one of the output of the reference image from the frame memory 203 from each of the reference images. Means 204 and whether or not a reference image has been input to the frame memory 203 to the memory input means 205.
The coding control unit 208 instructs the memory erasing unit 206 to independently erase the portion 03 for each of the reference images.
Is an image decoding device that receives the bit string.

The operation of the second embodiment of the present invention will be described with reference to FIG.

When processing the current input image, the encoding control unit 207 instructs the memory output unit 204 to select at most one of the reference images output from the frame memory 203 from each reference image. Together with the frame memory 2
03 determines whether or not the reference image is output from the frame memory 20.
The memory erasing unit 205 instructs the memory input unit 205 to interlock the presence or absence of the input of the reference image into the memory 3 and deletes the frame memory 203 in conjunction with not outputting the reference image from the frame memory 203. Instruct 206.

The current input image is encoded by the encoding unit 201
Is output from the memory output unit 2 in accordance with an instruction from the encoding control unit 207.
When the reference image is output at 04, the pixel signal is subtracted from the reference image. Conversely, if the memory output unit 204 does not output a reference image according to an instruction from the encoding control unit 207, nothing is performed. In this way, a bit string is generated.

The generated bit string is transmitted to the image decoding device 208
To the local decoding unit 202. When the memory output unit 204 outputs a reference image according to an instruction from the encoding control unit 207, the local decoding unit 202 adds a pixel signal to the reference image. Conversely, if the memory output unit 204 does not output a reference image according to an instruction from the encoding control unit 207, nothing is performed. In this way, a new reference image is generated.

When processing the next input image, the frame memory 203 outputs a reference image prior to the output reference image when the memory output unit 204 outputs a reference image in accordance with an instruction of the encoding control unit 207. The stored part of the frame memory 203 is erased by the memory erasing means 206 in accordance with the instruction of the encoding control unit 207,
The reference image is inputted and stored by the memory input means 205 in accordance with the instruction of (1). Conversely, when the memory output unit 204 does not output a reference image according to an instruction from the encoding control unit 207, all parts are erased by the memory erasing unit 206 according to an instruction from the encoding control unit 207. The plurality of reference images stored in the frame memory 203 are used to output the reference image by the memory output unit 204 according to an instruction from the encoding control unit 207 when processing the next or subsequent input image. You.

Here, as a configuration for storing a plurality of reference images in respective portions of the frame memory 203, a FIFO is used.
An operation of the embodiment when a memory is used will be described.

When a reference image is input by the memory input unit 205 in accordance with an instruction from the encoding control unit 207, first, the earliest reference image stored in the frame memory 203 is stored in the deleted frame memory 203. Remember
Next, a reference image next to the earliest reference image is stored in a portion of the frame memory 203 that stores the earliest reference image, and the same operation is repeated in the same manner. In the portion of the frame memory 203 that becomes
The newly generated reference image is input and stored.

When the portion of the frame memory 203 which stores the reference image preceding the output reference image is erased by the memory erasing means 206 in accordance with the instruction of the encoding control unit 207, the output reference image is stored. The portion of the frame memory 203 that is being used is set as the head of the output of the FIFO memory, and the portion of the frame memory 203 other than the FIFO memory is erased.

The above F when inputting a reference image is used.
As an operation method of the IFO memory, the frame memory 20 is used.
Rather than storing each reference image stored in 3 again, an operation method such as moving a pointer indicating each part of the stored frame memory 203 with respect to each reference image is also possible. is there.

It is also generally possible for the portion of the frame memory 203 to be erased to be a reference image that is not before the output reference image. In such a case, the operation method of the FIFO memory when erasing the portion is as follows.
For the portion of the frame memory 203 storing the reference image next to the output reference image, the frame memory 203 storing the reference image before the stored reference image is stored.
Is moved, and the part of the frame memory 203 storing the reference image to be output is
An operation method such as erasing the portion after setting the memory to something other than the O memory is possible.

As described above, when the memory output means 204 outputs the reference image from the frame memory 203 when processing the next input image, the reference image preceding the output reference image is stored. When the portion of the frame memory 203 is erased by the memory erasing means 206 and the memory output means 204 does not output the reference image from the frame memory 203, the memory input means 205 does not input the reference image to the frame memory 203. Thus, by erasing all the frames in the frame memory 203 by the memory erasing means 206, it is possible to solve the problem of the present invention of preventing the memory from being unnecessarily consumed in the image encoding device.

FIG. 3 is a diagram showing a configuration of an embodiment of the third invention according to the present invention.

In the figure, reference numeral 301 denotes an image coding apparatus for transmitting a bit sequence, 302 denotes a decoding unit which adds a reference image to an input bit sequence to generate a decoded image and newly generates a reference image, and 303 denotes a reference image. , A memory output unit for switching whether or not the reference image is output from the frame memory; a memory input unit for switching whether or not a reference image is input to the frame memory; Memory erasing means for erasing the frame memory;
3 to determine whether or not the reference image is output from the memory output means 30.
4, a decoding control unit that instructs the memory input unit 305 whether or not a reference image has been input to the frame memory 303, and instructs the memory erasure unit 306 to erase the frame memory 303.

The operation of the third embodiment of the present invention will be described with reference to FIG.

When processing the current input bit sequence, the decoding control unit 307 instructs the memory output unit 304 whether or not a reference image is to be output from the frame memory 303, and inputs the reference image to the frame memory 303. The memory input means 305 is instructed so that the presence / absence of the frame memory 303 is also linked, and the memory erasing means 306 is deleted so that the frame memory 303 is deleted in conjunction with not outputting the reference image from the frame memory 303.

When the decoding unit 302 outputs a reference image by the memory output unit 304 in accordance with an instruction from the decoding control unit 307 with respect to the input bit sequence received from the image encoding device 301, the decoding unit 302 outputs a pixel signal between the input image and the reference image. Is added. On the contrary, the memory output means 304 is operated by the instruction of the decoding control unit 307.
If the reference image is not output, nothing is done. In this way, a decoded image is generated and a new reference image is generated.

When the frame memory 303 does not output the reference image by the memory output means 304 according to the instruction of the decoding control unit 307 when processing the next input bit string, the frame memory 303 performs the processing by the memory erasing means 306 according to the instruction of the decoding control unit 307. Will be erased. Conversely, when the reference image is output by the memory output unit 304 in accordance with the instruction of the decoding control unit 307, the memory input unit 3 is preceded by the output and is output in accordance with the instruction of the decoding control unit 307.
At step 05, a reference image is input and stored.

As described above, when the memory output unit 304 does not output the reference image from the frame memory 303 when processing the next input bit string, the memory input unit 30
5 does not input the reference image to the frame memory 303, and erases the frame memory 303 by the memory erasing means 306, thereby preventing the image decoding apparatus from unnecessarily consuming the memory. It is possible to solve.

FIG. 4 is a diagram showing a configuration of an embodiment of the fourth invention according to the present invention.

In the figure, reference numeral 401 denotes an image coding apparatus for transmitting a bit string; 402, a decoding unit which adds a reference image to an input bit string to generate a decoded image and newly generates a reference image; A frame memory for storing an image; 404, a memory output unit for selecting at most one output of the reference image from the frame memory 403 from each of the reference images stored in the frame memory 403; A memory input unit 406 for switching whether or not a reference image is input to the frame memory 403;
Is a memory erasing means for independently erasing the frame memory 403 for each of the reference images. 407 is a memory output unit that selects at most one of the output of the reference image from the frame memory 403 from each of the reference images. Means 404, and instructs the memory input means 405 whether or not a reference image has been input to the frame memory 403, and instructs the memory erasing means 406 to delete portions of the frame memory 403 independently for each reference image. This is a decoding control unit.

The operation of the fourth embodiment according to the present invention will be described with reference to FIG.

When processing the current input bit string, the decoding control unit 407 instructs the memory output means 404 to select at most one reference image output from the frame memory 403 from each reference image. , The presence or absence of the output of the reference image from the frame memory 403
The memory erasing unit 405 instructs the memory input unit 405 to interlock the presence or absence of the input of the reference image to the memory 03, and erases the frame memory 403 in conjunction with not outputting the reference image from the frame memory 403. Instruct 406.

When the memory output means 404 outputs a reference image to the input bit sequence received from the image encoding device 401 in accordance with the instruction of the decoding control unit 407, the decoding unit 402 Is added. Conversely, the memory output means 404 is operated in response to an instruction from the decoding control
If the reference image is not output, nothing is done. In this way, a decoded image is generated and a new reference image is generated.

When the memory output means 404 outputs a reference image in accordance with an instruction from the decoding control unit 407 when processing the next input bit string, the frame memory 403 stores a reference image preceding the output reference image. The part of the frame memory 403 that has been erased is erased by the memory erasing unit 406 in accordance with the instruction of the decoding control unit 407, and the reference image is input and stored in the memory input unit 405 in accordance with the instruction of the decoding control unit 407. Conversely, when the memory output unit 404 does not output the reference image according to the instruction of the decoding control unit 407, all parts are erased by the memory erasing unit 406 according to the instruction of the decoding control unit 407. Frame memory 403
Are used for outputting the reference image by the memory output unit 404 in accordance with the instruction of the decoding control unit 407 when processing the next or subsequent input bit string.

Here, as a configuration for storing a plurality of reference images in respective portions of the frame memory 403, a FIFO is used.
An operation of the embodiment when a memory is used will be described.

When a reference image is input by the memory input unit 405 in accordance with an instruction from the decoding control unit 407, first, the earliest reference image stored in the frame memory 403 is stored in the deleted frame memory 403. Then, the reference image next to the earliest reference image is stored in the portion of the frame memory 403 in which the earliest reference image is stored, and so on. A newly generated reference image is input and stored in a portion of the frame memory 403 which is the head of the input.

When the portion of the frame memory 403 storing the reference image preceding the output reference image is deleted by the memory deletion unit 406 in accordance with the instruction of the decoding control unit 407, the output reference image is stored. The portion of the frame memory 403 that is being used is set as the head of the output of the FIFO memory, and the portion of the frame memory 403 other than the FIFO memory is deleted.

The above F when inputting a reference image is used.
As an operation method of the IFO memory, the frame memory 40
Rather than storing each reference image stored in the reference image 3 again, an operation method such as moving a pointer indicating each part of the stored frame memory 403 with respect to each reference image is also possible. is there.

It is generally possible that the portion of the frame memory 403 to be erased is a reference image that is not before the output reference image. In such a case, the operation method of the FIFO memory when erasing the portion is as follows.
For a portion of the frame memory 403 storing the reference image next to the output reference image, the frame memory 403 storing the reference image before the stored reference image is stored.
Is moved, and the portion of the frame memory 403 that stores the output reference image is
An operation method such as erasing the portion after setting the memory to something other than the O memory is possible.

As described above, when outputting the reference image from the frame memory 403 by the memory output means 404 when processing the next input bit string, the reference image preceding the output reference image is stored. When the portion of the frame memory 403 is erased by the memory erasing unit 406 and the memory output unit 404 does not output the reference image from the frame memory 403, the memory input unit 405 does not input the reference image to the frame memory 403. Then, by erasing all the frame memory 403 by the memory erasing unit 406, it is possible to solve the problem of the present invention of preventing the memory from being unnecessarily consumed in the image decoding apparatus.

[0066]

As described above, according to the image encoding apparatus of the first aspect of the present invention, the memory input means switches whether or not a reference image is input to the frame memory, and erases the frame memory. Since the memory erasing means performs,
When the reference image is not output from the frame memory, the frame memory can be erased without inputting the reference image to the frame memory, so that unnecessary consumption of the memory can be prevented.

According to the image encoding apparatus of the second invention, the memory input means switches whether or not to input a reference image to the frame memory, and erases the frame memory independently for each reference image. When the reference image is output from the frame memory, the portion of the frame memory that stores the reference image preceding the output reference image can be deleted. When the reference image is not output from the frame memory, it is possible to delete all the frame memory portions without inputting the reference image to the frame memory, thereby preventing unnecessary consumption of the memory. It becomes possible.

On the other hand, as described above, according to the image decoding apparatus of the third aspect of the present invention, the memory input means switches whether or not to input a reference image to the frame memory.
In addition, since the memory erasing means performs erasing of the frame memory, when the reference image is not output from the frame memory, the frame memory can be erased without inputting the reference image to the frame memory. It is possible to prevent unnecessary consumption.

According to the image decoding apparatus of the fourth aspect of the present invention, the memory input means switches whether or not a reference image is input to the frame memory, and erases the frame memory independently for each reference image. When the reference image is output from the frame memory, the portion of the frame memory storing the reference image preceding the output reference image can be deleted. When the reference image is not output from the memory, it is possible to delete all the frame memory portions without inputting the reference image to the frame memory, thereby preventing unnecessary consumption of the memory. Becomes

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an image encoding device according to an embodiment of the first invention according to the present invention.

FIG. 2 is a diagram illustrating a configuration of an image encoding device according to a second embodiment of the present invention;

FIG. 3 is a diagram illustrating a configuration of an image decoding device according to a third embodiment of the present invention;

FIG. 4 is a diagram illustrating a configuration of an image decoding device according to a fourth embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 101 encoding unit 102 local decoding unit 103 frame memory 104 memory output unit 105 memory input unit 106 memory erasing unit 107 encoding control unit 108 image decoding device 201 encoding unit 202 local decoding unit 203 ... Frame memory 204 ... Memory output means 205 ... Memory input means 206 ... Memory erasing means 207 ... Encoding control section 208 ... Image decoding apparatus 301 ... Image encoding apparatus 302 ... Decoding section 303 ... Frame memory 304 ... Memory output means 305 ... memory input means 306 ... memory erasing means 307 ... decoding control unit 401 ... image encoding device 402 ... decoding unit 403 ... frame memory 404 ... memory output means 405 ... memory input means 406 ... memory erasing means 407 ... decoding control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Ichikawa 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (4)

[Claims] An encoding unit configured to subtract a reference image from an input image to generate a bit sequence; a local decoding unit configured to add the reference image to the bit sequence to generate a new reference image; And a memory output unit that switches the presence or absence of the output of the reference image from the frame memory. A memory input unit for switching, a memory erasing unit for erasing the frame memory, and a control unit for controlling the memory input unit and the memory erasing unit based on switching of the presence or absence of a reference image of the memory output unit. An image encoding device characterized by the above-mentioned. 2. An encoding unit that subtracts a reference image from an input image to generate a bit sequence, a local decoding unit that adds the reference image to the bit sequence and newly generates a reference image, A frame memory for storing an image; and memory output means for selecting at most one output of the reference image from the frame memory from each of the reference images stored in the frame memory. An apparatus, comprising: memory input means for switching whether or not a reference image is input to the frame memory; memory erasing means for independently erasing the frame memory for each of the reference images; and reference to the memory output means. An image encoding device, comprising: a control unit that controls the memory input unit and the memory erasing unit based on selection of an image. 3. A decoding unit that adds a reference image to an input bit string to generate a decoded image and newly generates a reference image; a frame memory that stores the reference image; An image decoding device comprising: a memory output unit that switches whether to output a reference image; and a memory input unit that switches whether to input a reference image to the frame memory; and a memory erasing unit that erases the frame memory. An image decoding apparatus comprising: a control unit configured to control the memory input unit and the memory erasing unit based on switching of the presence or absence of a reference image of the memory output unit. 4. A decoding unit for adding a reference image to an input bit string to generate a decoded image and newly generating a reference image; a frame memory for storing a plurality of reference images; A memory output unit that selects at most one output of the reference image from each of the reference images stored in the frame memory, wherein the presence or absence of input of the reference image to the frame memory is provided. A memory input means for switching the frame memory independently for each of the reference images; and controlling the memory input means and the memory erasing means based on the selection of the reference image by the memory output means. An image decoding device, comprising: