JP3271634B2 - Digital image signal transmission device and reception device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image signal transmitting apparatus and a receiving apparatus capable of transmitting at a low bit rate.

[0002]

2. Description of the Related Art Digital image data of a moving image includes a very large amount of information. If the digital image data is to be transmitted as it is, the transmission bit rate becomes extremely high.
For this reason, when recording is performed using a low-rate recording medium with a limited transmission bit rate, such as when recording and reproducing digital image data using a magnetic tape or a magneto-optical disk, a conventional method is used. In general, data is compressed using the fact that an image is spatio-temporal information.

For example, digital image data is compressed and transmitted, for example, by taking the difference between frames of digital image data and compressing the difference using DCT (Discrete Cosine Transform). This has been done conventionally. Furthermore, in videoconferencing, etc., in consideration of the fact that images have little movement, it is necessary to transmit only one field of data instead of transmitting full frames, and to reduce the amount of information to transmit. And so on.

[0004] By reducing the number of fields to be transmitted, instead of one field, and sacrificing time information and securing spatial information, the image is beautiful but the movement may be jerky.

[0005] However, such a jerky movement impairs the quality of a moving image. Therefore, image data per frame is compressed as much as possible to transmit a full frame, and the spatial resolution is sacrificed. A method to enable full-motion playback as a video is also being considered.

[0006]

As described above, the conventional digital image signal transmission method is devised so as to reduce the transmission rate by compressing the image data in the time direction or the space direction.

However, when the transmission bit rate is reduced only by data compression, for example, when compression is performed in the time direction, the motion of the moving image becomes jerky, resulting in an unnatural image. Also, when the image is compressed in the spatial direction, the spatial resolution is degraded accordingly, and the reproduced image is degraded.

That is, in the conventional method, since the bit rate is reduced only by data compression, one of the data in the time direction or the space direction is sacrificed, or both are sacrificed, and the reproduced image is satisfactory. It was difficult to get something.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital image signal transmitting apparatus which is designed so that a reproduced image as beautiful as possible can be obtained even at a low transmission rate, and that the motion can be smoothly performed.

[0010]

According to a first aspect of the present invention, there is provided a digital image signal transmitting apparatus according to the first aspect of the present invention. A means 22 for dividing information on a moving object moving upward and information on a typical image of a plurality of image elements assumed to constitute an image of a natural object, a building, a structure, a creature, and other images are stored. Image element storage means 5, means 22 for forming approximate still image information in which the still image information of the separated background image is replaced with image elements from the image element storage means, and memory for storing the approximate still image information Means 23BGs, as the still image information of the background image, transmitting the identification information of each image element of the approximate still image and the screen position information thereof, and transmitting the background image separated from the input digital image signal. Characterized in that it comprises a transmitting means for transmitting the information of the change information and the moving object with respect to the approximate still image memory means.

In the digital image signal transmitting apparatus according to the present invention, a memory means 23BG for storing the separated still image information of the background image is provided. In addition to the identification information of each image element of the approximate still image and the screen position information, the difference between the previously separated background image and the approximate still image is transmitted, and the background image separated from the input digital image signal is transmitted. Transmission means for transmitting change information for the background image of the memory means 23BG and information of the moving object.

The digital image signal transmitting apparatus according to the present invention described in claim 3 is claim 1 or claim 2.
In the digital image signal transmission device according to the above, for the information of the moving object moving on the background image, in advance, one or more moving object planes each consisting of a still image of the moving object moving on the background image Separating means 22 for separating information;
A means 22 for forming approximate still image information in which each of the separated moving object plane information is replaced with an image element from the image element storage means, and an approximate still image information of each of the moving object planes are individually stored. Memory means 23A1s
Change information detecting means for detecting change information for the approximate still image stored as the moving object plane information based on the input digital image signal and the output of the memory means; and a still image of the moving object plane. A transmission means for transmitting the identification information of each of the image elements as information and transmitting the change information.

[0013]

In the present invention having the above structure, for example, when one scene composed of specific image contents is considered,
The image of the scene is divided into a background image considered as a fixed still image and information on a moving object.

Then, information of a still image and information of a moving object are transmitted. If the still image information is transmitted as it is while maintaining good image quality, the data amount becomes extremely large.

For this reason, in the present invention, a still image is captured as a plurality of image elements, and information on typical images of natural elements, buildings, structures, creatures, and other image elements assumed to constitute images in advance. Is registered and stored in the image element storage means, necessary image elements are read out, and background approximate still image information similar to a separated background still image is created. This approximate background image information can be reconstructed by providing the same image element storage means on the receiving side if the identification information of the image element constituting the approximate image information and the position information of the image element on the screen are known. can do.

According to this method, instead of the still picture information,
Since it is sufficient to transmit the identification information of the image element and the position information on the screen, the amount of transmission data can be greatly reduced. And
It is even better if the difference from the accurate background still image is transmitted as change information, for example, by data compression.

According to the third aspect of the present invention, information on a moving object is also transmitted separately from a still image of the moving object and change information such as a change in the motion. That is, in the invention of claim 3, a two-dimensional image of one frame of a moving image is regarded as an overlap of a two-dimensional plane including still images of a background and a plurality of moving objects. Then, with respect to the moving object, change information such as the moving direction, the moving distance, and the shape change of the moving object is extracted and transmitted.

In this case, it is necessary to transmit not only the information of the background still image but also the information of the still image of the moving object. The still image of the moving object is also transmitted from the image element storage means. The image element and its position information on the screen are transmitted instead of the still image information.

In the case of a moving object, the number of picture elements constituting the moving object is smaller than that of the background image, and a very small amount of transmission data is required. In this case, the difference between the accurate still image of the moving object and the approximate still image is included in the change information of the moving object and transmitted.

On the receiving side, a moving image is reproduced by superimposing the moving object of the moving object plane on the background image of the background plane according to the change information. That is, a moving image is reproduced by synthesizing a still image with high image quality, and the reproduced image has high image quality.

In this case, it is sufficient to transmit information for a still image of each of the background plane and the moving object plane for one scene. Since only the change information needs to be transmitted in addition to the information for the still image, the amount of information to be transmitted for the image of one scene may be very small. Even if there is, it can be transmitted sufficiently.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital image signal transmission apparatus according to the present invention applied to a disk device using a magneto-optical disk as a transmission medium (recording medium) will be described with reference to the drawings.

The apparatus of this embodiment includes a video camera unit using, for example, a CCD type solid-state imaging device, and converts an image signal obtained by shooting with the video camera unit 1 into a digital image signal by an A / D converter. To record on a magneto-optical disk. In this example, a portion of a reproducing device described later is provided together with the recording device.

[Description of Disk Recording Apparatus for Digital Image Signal] FIG. 1 shows a disk drive system and a block diagram of the apparatus of this embodiment.
It comprises a recording signal system 2, a system controller 3 for controlling the whole system, and a disk drive system 10, and an image pickup output signal of the video camera unit 1 is recorded via the recording signal system 2. I have.

In the disk drive system 10, reference numeral 11 denotes a magneto-optical disk. The magneto-optical disk 11 is housed in a cartridge 11A. Further, a pre-groove for light spot control (for tracking control) is formed on the disk 11 in advance, and in this case, the absolute address is superimposed on the wobbling signal for tracking in this pre-groove. Data is recorded. The absolute address data is used for controlling the recording track position at the time of recording and for controlling the reproduction scanning track position at the time of reproduction described later.

The disk 11 is rotated by a spindle motor 12. The rotation of the spindle motor 12 is controlled by a servo control circuit 15 so that the disk 11 is controlled to rotate at a constant linear velocity, for example.

The disk 11 is provided with a shutter. When the disk 11 is placed on a disk mounting tray and loaded in the apparatus, the shutter is opened. A magnetic head 13 for recording is arranged above the shutter opening of the disk 11 to face it, and an optical pickup 14 is arranged below the shutter opening of the disk 11 to face it.

The optical pickup 14 has a light emitting portion and a light receiving portion, and is controlled by a feed motor 16 to move in the radial direction of the disk 11. The servo control circuit 15 controls the focus and tracking of the optical pickup 14.

The system controller 3 is equipped with a microcomputer and manages the entire operation. The system controller 3 includes a key group 4
Provides a key input signal. Key group 4 includes an imaging / recording standby key, an imaging / recording start key, a playback key,
A stop key is included.

[Explanation of Recording Operation] In this example, a moving image captured by the video camera unit 1 is recorded separately into a fixed background part and a moving part moving on the background. The fixed background portion is registered in a background plane memory 23BG described later,
Recorded as still image information. However, instead of recording the still image information of the background plane as it is, the typical image information of a natural object, a building, a structure, a creature, and other image elements that are assumed to constitute an image are prepared in advance. An approximate still image of a background plane is created, and instead of recording image information, identification information of an image element constituting the approximate still image and information of its screen position are recorded.

Then, the difference between the approximate still image and the correct background still image is recorded while being included in the background change information. The change information of the background includes pan, tilt,
Also included is background image information that changes when an operation of changing a shooting image frame by zooming or the like is performed.

The moving part is separated into each moving object, and the moving object plane memories 23A1 to 23A to be described later.
n, the information of the still image of the moving object is recorded, and the change information of the moving object of each moving object plane is recorded. Also in this case, the still image information of the moving object plane is replaced with an approximate still image in the same manner as the background image, and the identification information is recorded.

For this moving part, the difference between the approximate still image and the still image of each moving object, the moving direction and the moving amount of the moving object, and the change of the image according to the movement are also shown in the moving part. Recorded as change information.

In this example, as shown in FIG. 2, recording of one scene is performed in a preparation period and an actual imaging and recording period. Then, in the preparation period, the above-described recording processing of the still image information of the background plane and the moving object plane is performed. In the actual imaging and recording period, only the change information on the background and the change information on each moving object are recorded.

In this case, as shown in FIG. 3, for example, the still image information for one screen is composed of 480 lines × 720 pixels, and the data of one pixel is represented by a luminance signal Y (8 bits).
And color information U and V (8 bits).

When the captured image is, for example, a two-dimensional image 30 as shown in FIG. 4, a fixed background still image composed of a stationary building or the like is extracted as a background plane 31 as shown in the figure. Then, in the example of FIG. 4, an airplane, a monkey, and a car are recognized as moving objects, and are separated as moving object planes 32, 33, and 34, respectively. The separated plane information is stored in the background plane memory 23BG.
And the moving object plane memories 23A1 to 23An.

As shown in FIG. 5, for example, a large number of typical image information of natural objects, buildings, structures, living things, and other image elements assumed to constitute an image are stored in the image element memory 5. I have. The image of the image element stored in the image element memory 5 includes a standard equipment prepared in advance and an image captured and stored by the user.

However, any of the image elements can be read out with the identification information given in correspondence with the address of the memory 5. For example, in the example of FIG. 5, a number is assigned to each image element, and identification and reading can be performed with the number.

[A. Recording of Preparation Period] In this example, in the preparation period, the signal processing circuit 22 separates the still image of the background plane and the moving object plane from the input image signal, and separates them into the background plane memory 23BG and the moving object plane memory. Write to 23A1 to 23An. Further, an approximate still image using the image elements in the image element memory 5 is generated from the still images in the memories 23BG and 23A1 to 23An.

That is, the imaging signal from the camera unit 1 is
The signal is supplied to the A / D converter 21, and for example, one pixel sample is converted into an 8-bit digital image signal and supplied to the signal processing circuit 22. The signal processing circuit 22 converts the image of the scene captured by the camera unit 1 into a background plane composed of a stationary still image of a fixed background and a moving object composed of a still image of each moving object moving on the background. Separate with the plane.

Then, in the signal processing circuit 22, the separated background plane is written into the background plane memory 23BG. The n separated moving object planes are written in moving object plane memories 23A1 to 23A (n is a natural number). A specific embodiment for separating the background plane and the moving object plane will be described.

[A-1. Embodiment of Plane Separation Processing Circuit] FIG. 6 is a block diagram of an embodiment of a plane separation processing circuit for separating the signal processing circuit 22 into a background plane and a plurality of moving object planes.

That is, the 8-bit image data of one pixel from the A / D converter 21 through the input terminal 41 is supplied to the frame memory 42 and the subtraction circuit 44
And supplied to the subtraction circuit 45. The input image data is supplied to the moving object plane separation circuit 62 via the AND gate 61.

The frame memory 42 stores data of 8 bits per pixel for one frame.
Pixel data corresponding to the same sampling position in the previous frame is subtracted from the input pixel data. This subtraction circuit 4
The difference output of No. 4 is supplied to an absolute value conversion circuit 46 to be converted into an absolute value, and is supplied to a comparison circuit 47.

The threshold value θ1 is supplied to the comparison circuit 47 via a terminal 48. When the absolute value of the difference output from the absolute value conversion circuit 46 is smaller than the threshold value θ1, it becomes “1”, and the threshold value θ1 In the above case, a determination output of “0” is obtained. This judgment output is supplied to the weight coefficient control circuit 49.

In FIG. 6, reference numeral 23BG denotes the background plane memory shown in FIG. 1. As will be described later, after the initial state has passed, a background plane image (still image) is stored in the background plane memory 23BG. You. Also, 50
Is a weight coefficient memory in which weight coefficients of one frame are stored. The weight coefficient memory 50 stores, for example, a 3-bit weight coefficient.

The address of the frame memory 42, the background plane memory 23BG, and the weight coefficient memory 50 are commonly controlled by the output of the address control circuit 43, and the same address is designated.

In the subtraction circuit 45, the image data from the background plane memory 23BG is subtracted from the input pixel data, the difference output of the subtraction circuit 45 is supplied to the absolute value generation circuit 51, and the absolute value of the difference output is obtained. The absolute value of the difference from the absolute value conversion circuit 51 is supplied to a comparison circuit 52,
The absolute value of the difference output between the input pixel data and the background pixel data is compared with the threshold value θ2 through the terminal 53,
A determination output that becomes “1” when the value is less than 2 and “0” when the value is equal to or more than the threshold value θ2 is obtained from the comparison circuit 52. The judgment output from the comparison circuit 52 is supplied to the weight coefficient control circuit 49.

The difference output between the input pixel data and the background pixel data from the subtraction circuit 45 is also supplied to a multiplication circuit 54 and multiplied by a weight coefficient α generated from a weight coefficient control circuit 49. The multiplication output of the multiplication circuit 54 is
5 is added to the background pixel data from the background plane memory 23BG, and the added output is written to the background plane memory 23BG.

The weighting factor from the weighting factor control circuit 49 is
The weight coefficients written to the weight coefficient memory 50 and read from the weight coefficient memory 50 are supplied to the weight coefficient control circuit 49.

The weight coefficient control circuit 49 determines whether or not the pixel data is a motion pixel from the determination outputs of the comparators 47 and 52.

In the above configuration, the background plane memory 23BG, the subtraction circuit 45, the multiplication circuit 54, and the addition circuit 5
Reference numeral 5 denotes a digital filter using the background plane memory 23BG as a one-frame delay element. That is, if the weighting coefficient is α, the input pixel data of the k-th frame is Zk, and the background image data read from the background plane memory 23BG is X (k−1), the background pixel data of the k-th frame (estimated value ) Xk is given by the following equation.

Xk = α · (Zk−X (k−1)) + X (k−1) = (1−α) · X (k−1) + α · Zk In this example, one scene in which the background does not change Is fixed at, for example, 1/16. The white noise included in the input image is removed by repeating the operation represented by the above expression over a plurality of frames, and the S / N of the background image stored in the background plane memory 23BG is improved.

When the background is switched, for example, when the scene changes, that is, when the image-capturing scene changes to another image-capturing scene, the response time is shortened and the effect of colored noise is reduced. And the weighting factor α is 1
From / 16, multiply by 2 for each frame. In other words, the background image is gradually updated using the weighting coefficient α that increases exponentially in the order of 1/16 → 1/8 → 1/4 → 1/2 → 1. Therefore, the weight coefficient α is 5
There are types, each of which is represented by 3 bits.
The reason why the weighting coefficient α is a power of 2 is that the multiplication circuit 54
Is realized by a shift register or a selector.

In this example, after the initial state has passed, background still image data is stored in the background plane memory 23BG. The absolute value of the difference between the current pixel and the background pixel is detected by the subtraction circuit 45 and the absolute value conversion circuit 51. The absolute value of the difference is compared with the threshold value θ2 by the comparison circuit 52. When the absolute value of the difference is less than the threshold value θ2, it is determined that the current pixel belongs to the background image, and Processing is performed.

That is, in this case, the weight coefficient α is 2 ⁻⁴
(= 1/16). Then, in the multiplication circuit 54, the output of the subtraction circuit 45 is multiplied by the weight coefficient α, and the output of the background plane memory 23BG and the addition circuit 55
Are added. Then, the addition output is written to the same address of the background plane memory 23BG, and the background plane memory is updated. The weight coefficient at this time is written in the weight coefficient memory 50.

When the comparison circuit 52 determines that the absolute value of the difference between the current pixel and the background pixel is equal to or greater than the threshold value θ2, the current pixel detected by the subtraction circuit 44 and the absolute value Whether the absolute value of the difference from the corresponding pixel of the frame is less than the threshold value θ1 or not less than the threshold value θ1 is checked as an output of the comparison circuit 47. When the output of the comparison circuit 47 is less than the threshold value θ1, the following processing is performed.

That is, if the threshold value is less than the threshold value θ1, the background is switched due to a scene change or the like, and the weighting coefficient α (= 1/16) stored in the weighting coefficient memory 50 first is used. Is read out, and the multiplier 54 multiplies the output signal of the subtraction circuit 45 by the weighting coefficient α. Therefore, the updating of the background pixel performed in this frame is the same as the above described with Xk = 15/16 × X (k−1) + 1/16 × Zk.

When the background pixel is updated, α is doubled in the weight coefficient control circuit 49, and it is determined whether or not the new weight coefficient doubled is greater than 1. If it is smaller, the doubled weight coefficient α is stored in the weight coefficient memory 50. Starting from the weight coefficient of 1/16, (1/8 → 1/4 → 1/2 →
1) and the weighting coefficient α changes for each frame.

The background is switched, the weighting coefficient α changes as described above, and the process of updating the background pixel as described above does not proceed until 5 frames after α = 1. Therefore, even when the colored noise is erroneously detected as a new background pixel and undergoes the process of changing the weight coefficient, the correct background pixel is stored. The way of changing the weight coefficient α is set so that the response at the time of updating the background pixel is improved and the colored noise can be removed.

When the comparison circuit 47 determines that the absolute value of the difference between the current pixel and the previous frame pixel is equal to or larger than the threshold value θ1, this means that the current pixel is determined to be a motion pixel. In this case, the background plane memory 2
3BGs are not updated. For this motion pixel, a process of separating a motion plane is performed as described below.

In the weight coefficient control circuit 49, the comparison circuit 52 detects that the absolute value of the current pixel and the background pixel is greater than or equal to the threshold value θ 2, and determines from the output of the comparison circuit 47 The absolute value of the difference from the previous frame pixel is
If it is equal to or greater than the threshold value θ1, it is detected as a motion pixel.

The motion pixel detection signal from the weight coefficient control circuit 49 is supplied to an AND gate 61, and input digital pixel data from the input terminal 41 input to the AND gate is gate-controlled. This AND gate 61
Is high and open when the current pixel is a motion pixel. Therefore, when the input pixel (current pixel) is not a motion pixel, the output of the AND gate 61 is “0”,
When the input pixel is a motion pixel, the pixel data (this is data other than “0”; hereinafter, referred to as non-zero data) is output from the AND gate 61.

Reference numeral 62 denotes a moving object plane separation circuit, which includes a difference memory (frame memory) 62M capable of storing one frame of pixel data. The output of the AND gate 61 is input to the memory 62M. The memory 62M stores the frame memory 42 and the background plane memory 23BG according to the address control signal from the address control circuit 43.
It receives the same address control as the s and weight coefficient memory 50.

Therefore, the background image is removed from the current image and the difference memory 62M stores a difference image consisting of only a plurality of moving object images consisting of a set of motion pixels consisting of non-zero data. . And FIG.
As the data of the pixel other than the non-zero pixel data of the moving object, “0” data is written in the memory 62M as shown in FIG.

In this way, one 2
Pixel data of a plurality of moving objects in the three-dimensional image is
The data is written as non-zero pixel data having a level other than “0”, and the pixel data of the still image portion of the background image other than the pixels of the moving object is stored as all “0” data. Therefore, assuming that a plurality of moving objects do not overlap each other, the pixel data in the difference memory 62M is sequentially scanned, and non-zero pixel data other than “0” is associated (merged) with neighboring pixels. In addition, it is possible to separate the moving object plane including only each of the moving objects.

Reference numeral 63 denotes a microcomputer which scans the difference memory 62M of the moving object plane separating circuit 62, separates each moving object into planes as follows, and stores information on the separated moving object planes at corresponding addresses. In this case, the object plane memories 23A1 to 23An are written. The moving object plane memory 23
All “0” are previously written in all the addresses of A1 to 23An, and only the pixel of each moving object is stored at the same address as the difference memory 62M.
It is written in any of the moving object plane memories.

FIG. 9 and FIG. 10 are flowcharts of processing for separating the moving object plane by the microcomputer 63.
That is, in this case, the separation process of the moving object
In step 101, non-zero pixel data is searched (a motion pixel is not 0, so a motion pixel is searched). Then, if non-zero pixel data is found in step 102, the process proceeds to step 103, where it is checked whether the surrounding pixel data is non-zero. In the case of this example, as shown in FIG. 8, the data of eight pixels a to h at the top, bottom, left and right around the target pixel x are checked.

Then, in the next step 104, 8
If none of the data of the pixels a to h is non-zero, the pixel of interest x is regarded as an isolated point and
Then, the process returns to step 101 to search for the next motion pixel.

In step 104, if at least one of the eight pixels a to h has a non-zero pixel, the process proceeds from step 104 to step 105, where the pixel d on the left of the pixel x of interest and the upper pixel (one line before) It is checked whether or not the pixel and b are non-zero pixels, and the process proceeds to the next step.

In the next step 106, it is determined whether the left and upper pixels d and b are both non-zero.
When they are not non-zero, that is, they are not motion pixels,
Proceeding to step 107, a new number is set as the memory number of the moving object plane memory (hereinafter simply referred to as memory number). Then, the process proceeds to step 108, where the memory number is stored in correspondence with the address of the pixel.
Thereafter, the process proceeds to step 109, where it is determined whether or not scanning of all the pixels of the difference memory 62M has been completed. When all the scanning has been completed, this processing routine is terminated. If the full scan has not been completed, the process returns to step 101 to start searching for the next motion pixel.

If it is determined in step 106 that at least one of the left and upper pixels d and b is a non-zero pixel, the process proceeds from step 106 to step 110 to determine whether both are non-zero. Is determined. If both are determined to be non-zero, the process proceeds from step 110 to step 111, where the memory numbers stored in the microcomputer 63 for both pixels d and b are checked. And the next step 1
Proceeding to 12, it is determined whether the memory numbers of both pixels d and b match.

If the result of determination in step 112 is that the memory numbers of both pixels d and b match, the process proceeds from step 112 to step 108, where that memory number is stored corresponding to the address of the pixel of interest x. .

If it is determined in step 112 that the memory numbers of the pixels d and b do not match, the flow advances from step 112 to step 113 to select the memory number of the left pixel d. And stores the memory number in association with the pixel of interest x.
The memory number of the left pixel d and the memory number of the upper pixel b are related, and store information (called merge information) indicating that they are pixels of one moving object even if the memory numbers are different.

This is because the moving object is a pixel at a jump position in the data of a certain horizontal scanning line, but as a result of a search for a pixel on a subsequent line, it is found that the moving object is connected as a pixel of the same moving object. Shows the case.

If the result of determination in step 110 is that both are not non-zero, step 110
Then, the process proceeds to step 115, where it is determined whether or not the left pixel d is non-zero. If the result of this determination is that the left pixel d is non-zero, the process proceeds to step 116, where the memory number of that pixel d is checked, and thereafter, step 10
Proceeding to step 8, the memory number is stored in correspondence with the address of the target pixel x.

As a result of the determination in step 115, the left pixel d
Is not non-zero, that is, when it is determined that the upper pixel b is non-zero, the process proceeds to step 117, where the memory number of the upper pixel b is checked, and
08, corresponding to the address of the target pixel x,
The memory number is stored.

As described above, after step 108, the process proceeds to step 109, where it is determined whether or not the search for all the pixels in the difference memory 62M has been completed.
If the search has not been completed, the process returns to step 101, and the above processing routine is repeated.
This processing routine ends.

By the above-described pixel search of the difference memory 62M, the same memory number and the memory associated with the same memory number for the address of the pixel included in each moving object are stored in the built-in memory of the microcomputer 63 for each moving object. The number is stored along with information relating both memory numbers.
The microcomputer 63 assigns the memory number of the pixel recognized as the same moving object to the memory number of one moving image plane memory.
And correspond. Thus, each moving object can be separated as a separate moving image plane as follows.

That is, the microcomputer 63 sets the difference memory 6
The motion pixel data is sequentially read from 2M. The read output of the difference memory 62M is stored in the moving image plane memory 23.
A1 to 23An are input to each of them. Further, the microcomputer 63 sets the read pixel as described above, supplies the write pixel address (may be the same as the read pixel address) only to the stored moving picture plane memory of the memory number No, and sets the motion pixel Is written into the video plane memory of the memory number No.

Thus, the moving object plane memory 23A
In each of 1 to 23An, one moving object is
They are separated and stored separately.

In the above moving object plane separation method,
The difference memory 62M is stored in a horizontal
Pixels are searched vertically to merge pixels included in the same moving object.When one moving pixel is detected, surrounding pixels are searched sequentially to track non-zero pixels and merge. At the same time, the merged pixel data may be sequentially and simultaneously written to one moving object plane memory to complete the moving object plane memory for one moving object.

Even if two moving objects are overlapped at a certain point in time, the moving objects can be separately observed after a predetermined time has elapsed. By updating the memory at the time of recording the change information, the moving object plane memories 23A1 to 23An can accumulate the moving object plane information including only the moving objects by the above-described method.

[A-2. Generation of Approximate Still Image] As described above, the still images of the background plane and the moving object plane are
Separated from the input image signal, the memories 23BG, 23A
When stored in 1 to 23An, the signal processing circuit 22
A process of replacing these still images with image elements in the image element memory 5 is performed, and approximate still images are generated by the replacement.

That is, the signal processing circuit 22 first creates an approximate still image for the background still image in the background plane memory 23BG. There are various methods. For example, one image element is read from the image element memory 5 and a comparison search is performed between the image element and each part of the still image in the memory 23BG. If the value is smaller than the value, the still image portion is replaced with the image element. At this time, the position of the replaced still image portion on the screen is also stored.

Each image element in the image element memory 5 stores an enlarged image of a typical image of the image element in a state of relatively high definition. When reading from the memory 5, the size can be designated so as to correspond to the size of the corresponding portion of the background image to be replaced. That is, when reading is performed in a state larger than the stored image, reading is performed while interpolating data. When reading is performed in a state smaller than the stored image, data is thinned out and the size is adjusted.

In this case, the image elements read from the memory 5 and replaced with the background plane are displayed, for example, by scrolling all the image elements in the memory 5 on a viewfinder (not shown) of the camera unit 1. It is good to select and specify with. Of course, the above-described search can be automatically performed for all image elements. The approximate background still image generated in this way is
The data is written to the approximate background plane memory 23BGs.

Each of the moving object plane memories 23A1 to 23A1
For the still image of the moving object of 23An, an approximate moving object still image is generated using the image element of the image element memory 5 in the same manner as described above, and the approximate still image information is stored in the approximate moving object plane memories 23A1s to 23Ans. Is written to.

As described above, the approximate still image is generated, and the approximate plane memories 23BGs, 23A1s-2A
When the approximate still image is written in 3Ans, the recording information generation circuit 24 replaces the image information of the approximate still image with the recording information, but identifies the image elements constituting the approximate still image, for example, in this example. A process is performed in which the identification number and information indicating the position on the screen occupied by the image element are recorded information. In the case of the approximate moving object still image, if only the image information of the still image of the moving object is transmitted, the position information on the screen can be recorded by being included in the change information.
It is not necessary to include it in the record information during this preparation period.

The recording information on the still image from the recording information generating circuit 24 is supplied to a recording processing circuit 25. In the recording processing circuit 25, data processing conforming to the recording format of the disk 11, such as forming the data into a sector structure, is performed. The output data of the recording processing circuit 25 is sequentially supplied to the recording magnetic head 13 via the head drive circuit 27, and is magneto-optically recorded on the disk 11.

[B. Actual imaging / recording period] In this example, even in the imaging / recording period after operating the actual imaging / recording start key in the video camera unit 1, first, the signal processing circuit 22 And separates a background image and a still image of each moving object from the imaging signal. Then, the separated still image and the approximate background plane memory 23BG
s and each approximate moving object plane memory 23A1s to 23A
The approximate background still image and the approximate moving object still image information registered in ns are compared to generate change information as described above.

That is, the background information is based on the position of the approximate still image on the approximate background plane, and the information Vs of the change direction and the change amount (the direction and amount of pan and tilt, and further the zoom ratio) is obtained. , An approximate background still image,
Image information ΔPs corresponding to a change in difference from the background image separated from the current image is generated as change information for the background plane.

Further, for each moving object, image information ΔPm (true image information) of the difference between the moving direction and the moving amount Vm of each moving object and the moving object plane obtained from the current image with respect to the approximate moving object still image. , And change information due to movement change such as rotation and shape change).

Then, a process of recording the change information generated as described above on the disk 11 in real time is performed. That is, the change information generated as described above is supplied to the compression encoding circuit 26, compressed and encoded at an appropriate compression ratio, supplied to the recording processing circuit 25, and the data is converted into a sector structure. Performs data processing conforming to the recording format. The output data of the recording processing circuit 25 is sequentially supplied to the recording magnetic head 13 via the head drive circuit 27, and is magneto-optically recorded on the disk 11.

In this case, as will be described later, the change information to be recorded has a smaller number of bits as compared with the case where image information is compressed and transmitted, and even at a low recording transmission rate of 1.2 Mbps, More than enough can be recorded in real time. A specific embodiment of the above change information detection method will be described later.

Data recording on the magneto-optical disk 11 is performed as follows. That is, the magnetic field modulated by the recording data is applied to a predetermined position of the disk 11 by being supplied to the recording magnetic head 13 via the head driving circuit 27. Optical pickup 1
The laser beam from 4 is applied to the same position on the disk 11. At the time of recording, the recording track is irradiated with a laser beam having a constant power larger than that at the time of reproduction. By this light irradiation and the modulation magnetic field by the magnetic head 13,
Data is recorded on the disk 11 by thermomagnetic recording. The magnetic head 13 and the optical pickup 14 are configured to be able to move in the radial direction of the disk 11 in synchronization with each other.

At the time of recording, the output of the optical pickup 14 is supplied to the address decoder 29 via the RF amplifier 28, and the absolute address recorded in the pre-groove provided along the track of the disk 11 is recorded by the wobble. Data is extracted and decoded. Then, the detected absolute address data is stored in the recording processing circuit 25.
To the disk 11
Will be recorded. Further, the absolute address data is supplied to the system controller 3 and used for recognition of a recording position and position control.

At the time of this recording, a signal from the RF amplifier 28 is supplied to the servo control circuit 15, and a control signal for constant linear velocity servo of the spindle motor 12 is formed from a signal from the pregroove of the disk 11, The speed of the spindle motor 12 is controlled.

[B-1. Generation of Change Information of Background Image and Change Information of Moving Object] Next, a configuration example of a generation circuit of change information for an approximate background still image in the signal processing circuit 22 and change information of an approximate still image of each moving object will be described. This will be described with reference to FIG.

The change information is obtained from the current image information obtained by photographing with the video camera unit 1, from the approximate background plane memory 23BGs and the approximate moving object plane memory 23A.
It is generated using data of 1s to 23Ans.

That is, the image pickup data from the A / D converter 21 is separated into background plane information for one screen and plane information for each moving object by the plane separation circuit of the signal processing circuit 22 described above. The information of one frame of the background image and each moving object is stored in the frame memory 7.
1BG and 71A1 to 71An. The frame memories 71BG and 71A1 to 71An are configured as a two-frame buffer, and when information of a background image and a moving object is written to one frame memory, a background plane from the other frame memory and The information data of the moving object plane is read, and the data is used for generating change information.

The information of the background image from the frame memory 71BG is supplied to the change detection circuit 72BG, and the image information of each moving object from the frame memories 71A1 to 71An is supplied to the change detection circuits 72A1 to 72An. You. Then, the approximate background plane memory 23BGs
Is supplied to the change detection circuit 72BG and the approximate moving object plane memory 23A1s
Approximate moving object still image information stored in the preparation period during the preparation period is supplied to the change detection circuits 72A1 to 72An.

In the change detection circuit 72BG, the approximate background still image information is compared with the background image information in the frame memory 71BG, and the difference image information ΔPs between them is obtained. At the time of this comparison processing, information V of the moving direction and the moving amount of the camera
s is referenced. Based on the information Vs, a change in the image frame position due to panning, tilting, or the like is detected, and the difference information is detected in a state where the image frame positions differ from each other by the image frame change. Information increased by panning, tilting, and the like is detected as change information as it is.

Although this information Vs is not shown, the camera unit 1 is provided with sensor means such as a gyroscope for detecting the moving direction and distance when the camera is moved by tilting or panning. The detection is made by this sensor means. Also, for example, when the present apparatus is to be mounted on a tripod for an image pickup apparatus to perform shooting,
The tripod is provided with a sensor for detecting the direction and the amount of movement of the pan and tilt of the camera.
s may be obtained.

The change information Vs and ΔPs for the approximate background plane thus obtained are supplied to the compression encoding circuit 26.

In the motion change detection circuits 72A1 to 72An, each of the approximate moving object plane memories 23A1s to 23An
By performing pattern matching between the approximate moving object still image information stored in s and the moving object images from the frame memories 71A1 to 71An, a motion vector of the moving object, that is, a direction of the motion and a motion amount are obtained. Can be

In this case, since the moving object is stored in the memory as a moving object plane in advance, if the shape does not change, a particular representative point or a representative block is focused on and the representative point or the representative block is focused on. By performing pattern matching on, it is possible to extract a motion vector for the entire moving object, and it is possible to perform matching processing in a relatively short time. The same can be said for the case of detecting the change information of the background image.

When a moving object changes its direction or shape, an error becomes large only by pattern matching. Therefore, in this example, the error is transmitted as change information together with the motion vector.

Thus, the motion change detection circuits 72A1 to 72A7
The motion vector and the matching error change information of the moving object of each moving object plane memory obtained in 2An are supplied to the compression encoding circuit 26.

The compression encoding circuit 26 compresses the input data. As described above, the amount of data after compression is very small as compared with image information, and can be easily recorded on a disk in real time.

When the camera is zoomed,
The zoom ratio information is included in the change information, and the information on the approximate background plane and the approximate moving object plane is passed through a low-pass filter (data thinning) according to the zoom ratio, or compared with the image signal. It performs interpolation.

The position of the moving object in each moving object plane memory after the movement can be easily detected as an address on the memory by using the detected motion vector. For this reason, the state in which the moving objects overlap each other can be recognized by the fact that the addresses of the pixels of the plurality of moving objects are the same. As described above, when a plurality of moving objects overlap, the depth between the moving objects is detected based on which moving object pixel appears as a pixel of that part in the current image. Then, the depth information is transmitted together with the motion information. Note that the depth information is also obtained for a background image and a moving object.

In the above example, the change information on the background image and the moving object is stored in the approximate plane memory 23BG.
Although the approximate still images of s, 23A1s to 23Ans are used as a reference, still image information of the background plane memory 23BG and the moving object plane memories 23A1 to 23An may be used.

In this case, as background plane information and moving object plane information recorded during the preparation period, in addition to the identification information of the image elements constituting the approximate still image and its screen position information, the background plane memory 23BG and the moving object plane Differences between the still image information of the plane memories 23A1 to 23An and the approximate still images of the approximate plane memories 23BGs and 23A1s to 23Ans are recorded in advance.

As described above, the criterion for detecting change information is:
By using the still image information of the background plane memory 23BG and the moving object plane memories 23A1 to 23An, the amount of change information can be reduced.

Further, in this case, as the motion change information on the moving object, a predicted motion vector as shown in the following example and object deformation information may be transmitted.

That is, in the example of FIG. 12, the frame information of each moving object extracted from the input image information from the frame memories 71A1 to 71An is obtained by the difference calculation circuit 7
3A1 to 73An.

The moving object plane memory 23A1-2
The 3An moving object plane information is output from the prediction circuits 74A1 to 74A7.
4An and supplied to the prediction motion vector generation circuit 75A1.
Based on the predicted motion vector from .about.75An, the frame image data of each moving object to be predicted at the present time after the movement is obtained. Then, the predicted frame image data of each moving object is calculated by the difference calculation circuits 73A1 to 73A1.
73An and supplied to the frame memories 71A1 to 71A.
The difference from the frame information of each moving object extracted from the input image information from An is calculated.

The difference calculation circuits 73A1 to 73An output the difference about the image of the moving object to the compression encoding circuit 26 as output data. Also, the difference calculation circuit 73A
1 to 73An determine the difference of the motion vector from the difference of the image of the moving object, supply the difference to the compression encoding circuit 26 as output data, and also supply the prediction data to the prediction motion vector generation circuits 75A1 to 75An for the next frame. A predicted motion vector for each moving object is generated.

As described above, information such as the recording position of the recorded data is recorded on the disk 11. That is, the background plane information, the moving object plane information, and the change information of each scene are each track, and further,
Information on which sector is recorded on the disk 11
Are recorded in a disc management area called a TOC (Table Of Contents) area provided at the innermost circumference of the disk.

In the above example, the information of the initial plane of the background image and the still image of the moving object is separated from the input image. However, the background image and the moving object are photographed by the camera in a state where they are separated from each other in advance. If possible,
These are individually imaged, and the background plane memory 2
3BG and moving object plane memory 23A1 to 23An
Can be written as initial plane information.

[Description of Disc Reproducing Apparatus for Digital Image Signal] FIG. 1 is a block diagram showing an embodiment of the disc reproducing apparatus of this embodiment. In this example, the same parts as those in the disk recording apparatus of FIG.

When the disc 11 is loaded into the apparatus, the apparatus first takes in the TOC area of the disc, and the system controller 3 records the background plane and the moving object plane of each scene and the recording position of the change information. Recognize.

Then, from the TOC area information, the system controller 3 first reproduces the information of the background plane and the plurality of moving object planes of the scene to be reproduced.

The information extracted from the disk 11 is supplied from the RF circuit 28 to the reproduction processing circuit 81.
Decoding processing of data of a predetermined recording format such as a sector structure is performed, and the decoded data is supplied to the plane forming circuit 82. Then, in this circuit 82, the identification information (number) of the reproduced image element
The image element in the image element memory 5 is read, and a still image is formed using the position information on the screen. This is performed for each of the background image and the moving object, and the approximate still images formed respectively are stored in the background plane memory 83BG.
And written into the moving object plane memories 83A1 to 83An.

When the reference of the change information is not an approximate still image but a regular still image, and the difference information between the approximate still image and the regular still image is recorded during the preparation period for recording. The difference information is used for the background plane memory 83BG and the moving object plane memories 83A1 to 83A1.
A regular still image is written in 83An. Thus, the preparation for starting the reproduction of the moving image is completed.

Next, background picture change information of the scene,
Moving object change information, depth information, etc
With reference to the C area information, extracted in real time,
The data is supplied to the data decompression / decoding circuit 84 via the F circuit 28 and the reproduction processing circuit 81. Then, the change information and the like are decompressed and decoded, and supplied to the signal processing circuit 85.

The signal processing circuit 85 includes a background plane memory 83BG and a moving object plane memory 83A1 to 83A1.
Each still image information from 83An is also supplied. In the signal processing circuit 85, the background plane memory 8
The background image from 3BG has a moving object plane memory 83A1
The image of each moving object from .about.83An is synthesized using the respective change information and depth information from the decompression decoding circuit 84.

That is, the composition is such that the moving object is pasted on the background image for each frame or field at the position according to the motion change information and the overlap according to the depth information (there is also the overlap with the background image). Then, the original moving image is obtained.

The moving image data from the signal processing circuit 85 is converted back to the original analog signal by the D / A converter 86, is derived from the output terminal 87, and is output to the image monitor device connected to this output terminal to reproduce the reproduced image. Is projected.

As described above, the information of the background plane and the moving object plane is firstly read out from the disk for each scene, and then the change information is sequentially read out from the disk, whereby the moving image of each scene can be reproduced. it can. In this case, since the amount of change information of each scene is very small, the change information of one scene is not taken out from the disk in real time of the moving image, but a buffer memory is provided, and the change information of each scene is provided following each plane information. It is also possible to take out the motion change information, accumulate it in the buffer memory, and sequentially read out the motion change information from the buffer memory in accordance with the moving image.

In such a case, the moving image reproduction process and the extraction of the reproduction signal from the disc can be separated, so that during the reproduction of the previous scene, the plane information of the next scene is recorded on the disc. , And can be stored in another plane memory. By doing so, it is possible to continuously reproduce a plurality of scenes without interruption.

As described above, according to the present invention, an input image is divided into a background image and a moving object plane, and these are recorded with high image quality. Since the data is recorded and synthesized at the time of reproduction, even in the case of a recording medium having a low recording transmission rate, it is possible to record a moving image with high image quality and smooth motion.

For example, a method of compressing image data, so-called MPEG, is conventionally known. In this method, image information of one frame (still image) is transmitted first, and thereafter, the first image is transmitted. Is a method of taking the difference from the image frame, and compressing and recording the residual. The bit number of the image data of the first frame in the MPEG is, for example, 400 K bits at the stage of data compression. This 400 Kbit image is an image having relatively high image quality.

Since the image of 400 K bits is information of one frame, if this is expressed in bps, one second is
Since it is composed of 30 frames, it is equivalent to 12 Mbps.
Therefore, a considerably high-quality image is obtained. MP
In the EG, only the residual information is recorded as subsequent information, so that the reproduced image is deteriorated.
The image of the first one frame itself has a good image quality.

On the other hand, according to the above-described configuration of the present invention, information of a plurality of image planes including a background plane and a moving object plane is recorded as image data equivalent to 12 Mbps equivalent to MPEG, and a bit Based on the motion change information recorded as a number, the moving image plane with good image quality is moved and the moving image is reproduced by synthesizing it with the background plane. Since the information is real-time information, the motion is good without jerking.

Further, according to the present invention, the information of the background plane and the moving object plane is transmitted by replacing it with an approximate still image composed of image elements prepared in advance. Since it is only necessary to transmit the position information, the still image can be recorded with a smaller amount of information as compared with the case where the still image information is transmitted as it is.

It should be noted that the motion information separated from the background plane is not recorded as a moving object plane composed of still images of a plurality of moving objects, as in the above example, but is recorded on the plurality of moving objects. The present invention can also be applied to a device that compresses motion information including a character and records it separately from a background plane.

In the above example, a magneto-optical disk was used as a transmission medium for image data. However, tape and other recording media, and further, transmission of image data via a transmission path using a cable or radio waves. It goes without saying that the present invention is applicable to transmission.

[0140]

As described above, according to the present invention, the image is divided into the background still image information (background plane) and the motion information, and the background still image information is transmitted and the moving image of the moving image is transmitted. The background change in one scene is transmitted as a difference from the background still image, and the background still image and the motion information are synthesized on the reproducing side. In this case, in the present invention, the still image information of the background image is not transmitted as it is, but an approximate still image is created by replacing the image element prepared in advance, the background image, and the image element is replaced with the image element. Since the identification information and the position information of each image element on the screen are transmitted, the amount of information can be significantly reduced.

Further, with respect to the motion information, when the still image planes of a plurality of moving objects and the changes thereof are recorded, the still image planes of each moving object are also recorded in the same manner as the background information. If an approximate still image is generated using an image element and the identification information of the image element is transmitted, the amount of transmitted information can be further reduced.

On the receiving side, a moving image plane with good image quality is moved based on the motion change information and synthesized with the background plane to reproduce a moving image. Thus, it is possible to obtain a good reproduced image without jerky movement.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disk recording device as one embodiment of a digital image signal transmission device according to the present invention.

FIG. 2 is a diagram for explaining signal recording timing in the example of FIG. 1;

FIG. 3 is a diagram for explaining the example of FIG. 1;

FIG. 4 is a diagram for explaining a main part of the present invention.

FIG. 5 is a diagram for explaining a main part of the present invention.

FIG. 6 is a block diagram of an embodiment of a main part of a digital image signal transmission device according to the present invention.

FIG. 7 is a diagram for explaining the operation of the example of FIG. 6;

FIG. 8 is a diagram for explaining the operation of the example of FIG. 6;

FIG. 9 is a diagram showing a part of a flowchart of the operation of the example of FIG. 6;

FIG. 10 is a diagram showing a part of a flowchart of the operation of the example in FIG. 6;

FIG. 11 is a block diagram of a main part of an embodiment of a digital image signal transmission device according to the present invention.

FIG. 12 is a block diagram of another embodiment of a main part of a digital image signal transmission device according to the present invention.

FIG. 13 is a block diagram of an embodiment of a reproducing apparatus for a digital image signal recorded by the apparatus of the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 22 signal processing device 23BG background plane memory 23BGs approximate background plane memory 23A1 to 23An animal plane memory 23A1s to 23Ans approximate animal plane memory 24 compression circuit 26 compression encoding circuit 31 background plane 32 to 34 animal plane memory 62 animal plane Separation circuit 62M Difference memory 72BG Picture frame position change detection circuit

Claims (8)

(57) [Claims] 1. A means for separating in advance a still image information of a background image forming a screen and information of a moving object moving on the background image, and information of typical images of a plurality of image elements are stored in advance. Means for forming approximate still image information obtained by replacing the still image information of the separated background image with an image element from the image element storage means, and storing the approximate still image information And memory means for transmitting identification information of each image element of the approximate still image and screen position information thereof as still image information of the background image, and for storing the background image separated from an input digital image signal. A transmission device for transmitting a digital image signal, comprising: transmission means for transmitting change information for an approximate still image and information of the moving object. 2. A means for separating in advance still image information of a background image forming a screen and information of a moving object moving on the background image, and information of typical images of a plurality of image elements are stored in advance. Image element storage means, memory means for storing the still image information of the separated background image, and approximation in which the still image information of the separated background image is replaced with the image element from the image element storage means. Means for forming still image information; as the still image information of the background image, in addition to the identification information of each image element of the approximate still image and the screen position information, the previously separated background image and the approximate still image A digital image signal transmission means for transmitting a difference between the input image signal and a background image separated from an input digital image signal, and transmission means for transmitting change information with respect to the background image in the memory means and information on the moving object; Location. 3. The apparatus for transmitting a digital image signal according to claim 1, wherein the information of the moving object moving on the background image is determined in advance with respect to the information of the moving object moving on the background image. Separating means for separating one or a plurality of moving object plane information composed of still images; and means for forming approximate still image information in which each of the separated moving object plane information is replaced by an image element from the image element storage means. Memory means for individually storing the approximate still image information of each of the moving object planes; and an approximate still image stored as the moving object plane information based on the input digital image signal and the output of the memory means. Change information detecting means for detecting change information for the image object; transmitting identification information of each of the image elements as still image information of the moving object plane; And a transmission unit for transmitting information. 4. The transmission apparatus of a digital image signal according to claim 1, wherein information of the moving object moving on the background image is determined in advance for each of the moving objects moving on the background image. Separating means for separating one or a plurality of moving object plane information composed of a still image; memory means for individually storing each of the moving object plane information; and an image element for storing the separated moving object plane information. Means for forming approximate still image information replaced with image elements from storage means; change information detecting means for detecting change information for the moving object plane information based on the input digital image signal and the output of the memory means; The identification information of each image element of the approximate still image and the difference between the approximate still image and the still image of the memory unit are transmitted as the still image information of the moving object plane. And a transmission unit for transmitting the change information. 5. The digital image signal transmitting apparatus according to claim 1, wherein the information on the moving object or the change information is compressed and transmitted. 6. The digital image signal is obtained by A / D-converting an image pickup output of a video camera, and the transmission means is a recording on a recording medium.
The transmission device for a digital image signal according to claim 4. 7. A receiving device for digital image information transmitted by the digital image signal transmitting device according to claim 1 or 3, wherein the image element is readable from the identification information of the image element. A certain image element storage unit, a unit for reading out a target image element from the image element storage unit based on the identification information of the image element in the received signal, and reproducing the approximate still image information using the screen position information; Memory means for storing the approximated still image information obtained as the background plane information and the moving object plane information, and generating background image information and moving object information using the plane information of the memory means and the change information. And a synthesizing means for synthesizing the two to obtain an output digital image signal. 8. A receiving device for digital image information transmitted by the digital image signal transmitting device according to claim 2, wherein the image element is readable from the identification information of the image element. A certain image element storage unit, a unit for reading out a target image element from the image element storage unit based on the identification information of the image element in the received signal, and reproducing the approximate still image information using the screen position information; Means for reproducing background plane information and moving object plane information from the approximated still image information obtained and the difference between the received true still image, and memory means for storing the background plane information and moving object plane information, respectively, Background image information and moving object information are generated by using the plane information and the change information of the memory means, and the two are combined and output digitally. Receiving apparatus for digital image signals and a combining means for obtaining an image signal.