JPH10174107A - Still image transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize image transmission even for a monitor control system utilizing a low speed channel by reducing a data quantity of differential image to be sent through a communication channel and enhancing a differential efficiency to generate the differential image. SOLUTION: Memories 105, 115 store same still images as a transmitter A1 and a receiver B1 as a reference image. The transmitter A1 takes a difference between a newest image received from a television camera 101 and the reference image to generate a difference image, and the processing to reduce a data quantity for each pixel is made, the image compression by the joint photographic experts group(JPEG) system is conducted to send the data to a communication line L1. The receiver B1 applies image expansion and decoding processing by the JPEG system to the received image to decode a differential image and the differential image is added to the reference image to reproduce a newest image and it is displayed on a CRT 118.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a transmitting device for compressing a still image input as an analog signal into digital data and transmitting the digital data, and a receiving device for expanding received still image data and displaying it on a display means. The present invention relates to a still image transmission device.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a block diagram of a video signal processing device to which an inter-frame differential transmission method described in Japanese Patent Application Laid-Open Publication No. H10-15064 is applied. In FIG.
An A / D 1 converts an analog video signal from the TV camera 1 into a digital video signal (hereinafter sometimes simply referred to as a video signal).
The converter 3 is a changeover switch for switching the video signal from the A / D converter 2 for each frame and outputting it to the frame memories 4 and 5, respectively, and the frame memories 4 and 5 are for holding the video signal for one frame. (A type of image memory), 6 is a subtractor for taking the difference between the video signals of the same coordinate point read from the frame memories 4 and 5 and outputting the difference, 7 is the switching control of the changeover switch 3 and A writing control device 8 for controlling the writing of the video signal, the video signal written in the frame memories 4 and 5 alternately uses the designated two points as the coordinate reference points and alternately outputs the video signal of the same coordinate point from the frame memories 4 and 5. The read control device 9 reads an analog video signal from the television camera 1 and processes the analog video signal.
A video signal processing circuit 10, which is a signal that can be copied to 0, is a monitor that can output an analog video signal from the television camera 1 as an image and specify a specific position on the screen with a light pen or the like.

Next, the operation of this conventional example will be described.
An analog video signal from the television camera 1 is converted into a digital video signal by the A / D converter 2 and output to the changeover switch 3. The write control device 7 has the changeover switch 3
And a write control signal is output to the frame memories 4 and 5 in accordance with the switching timing, and the video signal switched for each frame by the switch 3 is written to the frame memories 4 and 5. That is, a video signal is written to the frame memory 4 for the first one frame period, and a video signal is written to the frame memory 5 for the next frame period. On the other hand, an analog video signal from the television camera 1 is supplied to a monitor 10 via a video signal processing circuit 9 and is displayed as an image.
The operator looks at this image and sees a still image portion, for example, a still object such as a pencil, for example, a frame memory 4.
By using a light pen or the like and touching a monitor image, a designation is made using the video signal portions corresponding to a1 and b1 and the a2 and b2 in the frame memory 5 as a coordinate reference. As a result, the coordinate reference information is provided from the monitor 10 to the reading control device 8. Thereafter, the read control unit 8 alternately reads the video signals of the same coordinate point from the frame memories 4 and 5 and sequentially inputs these video signals to the subtracter 6 when the video signal portions of a1, b1, a2 and b2 are read. Is read as a coordinate reference. Therefore, the video signal portion a1 in the frame memory 4 moves to the video signal portion a2 in the frame memory 5 due to the slight movement of the visual field of the television camera 1, and the video signal portion b1 similarly moves to the video signal portion b2. Also,
These video signal portions are read out by the readout control device 8 as the same coordinate points as the readout, and output to the subtracter 5. Since the difference between the video signals at the same coordinate point in the frame memories 4 and 5 is obtained in the subtracter 5, the video signal portion forming the still image is deleted in the subtracter 5. Accordingly, only the inter-frame difference video signal component of the video signal forming the moving image is obtained from the subtractor 5 based on the movement of the moving body, and the band of the video signal is compressed.

[0004]

In the conventional example as shown in FIG. 8, the difference between the video signal in the first one frame period and the next frame period is obtained, and a change point is extracted and transmitted to the communication line. Therefore, in the difference image obtained after the monitoring target image has changed greatly once, there is a problem that the amount of change in each pixel is large, the amount of data to be transmitted is increased, and the difference efficiency is reduced. When performing image transmission in the control system, there is a problem that it takes a long time to transmit the image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is intended to reduce the data amount of a differential image to be transmitted to a communication line and to increase the differential efficiency when creating a differential image. It is an object of the present invention to provide a still image transmission device capable of realizing a short-time image transmission even in a supervisory control system using a low-speed line.

[0006]

A still image transmitting apparatus according to a first aspect of the present invention converts a difference image between a latest image taken from an image pickup means (television camera 101) and a reference image which is the same still image as the receiving apparatus side. An image according to the JPEG method, in which the difference image is created and processed to reduce the data amount for each pixel, and the compression ratio increases as the amount of change between one pixel and the surrounding pixels decreases. A transmitting device A1 that performs compression and transmits the data to the communication line L1;
The image received via the communication line L1 is subjected to JPEG image expansion and restoration processing to restore the difference image,
A receiver B1 for reproducing the latest image by adding the difference image to a reference image, which is the same still image as the transmitting device, and displaying the image on a display (CRT 118).

[0007] In the still image transmission device according to the second invention, the transmission device A1 is an image pickup means (TV camera 101).
A latest image memory 106 for storing the latest image data based on an output signal from the image forming apparatus, a reference image memory 105 for storing the image data from the image pickup means as reference image data of the same still image as that on the receiving device side, Reference image update control means (reference image update control circuit 111) for performing control for updating the reference image data of 105; difference between the latest image data of the latest image memory 106 and the reference image data of the reference image memory 105; Subtraction means (subtractor 1)
07), a difference data reduction unit (difference data reducer 108) for inputting the difference image data and calculating each pixel data of the image to reduce the difference value, and performs JPEG compression on the reduced difference image data. JPEG compression means (JPEG compressor 109) to be applied and a transmission circuit 11 for transmitting image data from the JPEG compression means to the receiving device B1
0, the receiving device B1 includes a receiving circuit 112 that receives the image data from the transmitting device 10, and a JPEG decompressing unit (JPP) that decompresses the received image data by JPEG.
EG decompressor 113) and differential data restoring means (differential) for inputting the decompressed image data, calculating for each pixel data of the image, and restoring the differential image data reduced by the differential data reducing means on the transmitting device side Data restorer 114),
A reference image memory 115 for storing the same still image as that of the transmitting device as reference image data, and a reference image updating control means for performing control for updating the reference image data of the reference image memory 105 in the same manner as the transmitting device. (Reference image update control circuit 119) and the reference image memory 11
An adding means (adder 116) for adding the reference image data of No. 5 and the differential image data restored by the differential data restoring means, and the same still image as the image taken by the image taking means based on the output signal of the adding means. Display means (CRT 118) for displaying an image.

In the still picture transmitting apparatus according to the third aspect of the present invention, the output from the subtracting means is provided between the subtracting means (subtractor 107) and the differential data reducing means (differential data reducing unit 108) in the transmitting apparatus A2. When the value of each pixel data indicated by the difference image data is smaller than a predetermined value, it is determined that the change amount is small and can be ignored, and the data amount of the difference image data is further reduced, and the difference data A change amount determining means (a change amount determiner 201) is provided.

In the still picture transmission apparatus according to the fourth invention, the transmission apparatus A3 requests the reference picture update control means (the reference picture update control circuit 111) to update the reference picture data at a constant cycle. The present invention is characterized in that reference image constant cycle update request means (reference image update timer 301) is provided.

In the still picture transmitting apparatus according to a fifth aspect of the present invention, when the transmitting apparatus A4 measures the data amount of the JPEG-compressed differential image and determines that the data amount is larger than the predetermined data amount, The image updating control means (reference image updating control circuit 111) is provided with a data amount measuring means (data amount measuring device 401) for instructing the updating of the reference image.

In the still picture transmitting apparatus according to a sixth aspect of the present invention, the transmitting apparatus A5 measures the total change amount obtained by summing up the change amounts of the respective pixels from the change amount determining means (the change amount determining unit 201). When the total change amount is larger than the previous change amount, the reference image update control unit (reference image update control circuit 111) is provided with a change amount measurement unit (change amount measurement unit 501) for instructing the update of the reference image. It is a feature.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, Embodiment 1 of the present invention. Will be described with reference to the drawings. FIG. 1 is a block diagram of the still image transmission device according to the first embodiment. This still image transmission device includes a transmission device A1 and a reception device B1. First, the components provided in the transmission device A1 will be described. The TV camera 101 outputs an analog signal of the captured image, and the A / D converter 102 converts the analog signal into a digital signal. Changeover switch 10
Reference numeral 4 denotes a device for switching the output destination of the digital signal data input from the A / D converter 102 between the following two image memories. The write control device 103 controls a changeover switch and performs memory write control. Things. The reference image memory 105 is a memory for storing the same still image as the receiving device B1 as reference image data, and the latest image memory 106 is a memory for storing the latest image data from the television camera 101. The subtracter 107 calculates the difference between the reference image data in the reference image memory 105 and the latest image data in the latest image memory 106 and outputs difference image data. Difference data reducer 1
Numeral 08 is for inputting the difference image data and calculating each pixel data of the image to reduce the difference value. JPEG
The compressor 109 applies JPE to the reduced difference image data.
G compression is applied. The transmission circuit 110 transmits image data from the JPEG compressor 109 to the communication line L1. The memories 105 and 106 can store image data of at least one screen.

Next, the components provided in the receiving device B1 will be described. The receiving circuit 112 receives image data from the communication line L1.
Decompresses JPEG-compressed image data. The difference data restoration unit 114 receives the expanded image data, performs an operation for each pixel data of the image, and restores the difference image data reduced by the difference data reduction unit 108 of the transmission device A1. The reference image memory 115 stores the same still image as the transmission device A1 as reference image data, and is a memory capable of storing at least one screen of image data. Adder 116
Is for adding and outputting the reference image data of the reference image memory 115 and the difference image data restored by the difference data restoration unit 114. D / A converter 11
Numeral 7 is for converting a digital signal from the adder 116 into an analog signal, and a CRT 118 as a display means is for outputting the converted analog signal as an image. Further, the reference image control circuit 111 of the transmission device A1 and the reference image control circuit 1 of the reception device B1
Reference numeral 19 controls transmission of the reference image from the transmitting device to the receiving device because the transmitting device A1 and the receiving device B1 have the same reference image when the device is activated.

Here, features of the first embodiment will be described. JPEG (Joint Photograph)
Expert Group) compression processing is, for example, 8 × 8
DCT of image data corresponding to the block diagram of pixels
(Discrete Cosine Transform) operation, then the result of the DCT operation is quantized, and then the result of the quantization process is entropy-encoded to create compressed data. In the JPEG decompression process, the compressed data is entropy decoded, the result of the entropy decoding is inversely quantized, and the result of the inverse quantization is inversely DCT-operated to restore the original image data.

The transmitting apparatus A1 compresses a still image with a JPEG compressor 109 and transmits the compressed still image. The feature of JPEG compression is that the smaller the amount of change between one pixel of an image and the surrounding pixels, the higher the compression ratio.
In the first embodiment, in order to maximize the compression effect of this JPEG compression, the RGB (color data) values for each pixel of the difference image before JPEG compression are set to a predetermined value (N ) To reduce the numerical value of each pixel of the difference image to reduce the amount of change between adjacent pixels at the change point.

FIG. 2 shows an example of a difference image to explain the effects of the above features. A is the reference image, B is the latest image, C
Is a difference image obtained by subtracting the difference of the reference image A from the latest image B, and D is a difference image obtained by dividing each pixel of the difference image C by 4 by the difference data reducer 108. When the difference between adjacent pixels in the third row of the latest image B is calculated from the first column, they are 10, 20, 45, 25, and 10. Difference image C
When the difference between adjacent pixels in the third row is calculated from the first column, 0,
0, 5, 25 and 10. When the difference between adjacent pixels in the third row of the difference image D is calculated from the first column, 0, 0, 1, 6,
It becomes 3. The difference image C is smaller than the latest image B, and the difference image D is smaller than the difference image C in that the difference between the adjacent pixels is smaller.
When the EG compression is performed, the image data after compression becomes smaller in the order of the latest image B, the difference image C, and the difference image D. By dividing each pixel of the difference image, JPEG
The compression effect at the time of compression is enhanced, and the amount of data to be transmitted is reduced. Further, since the division is performed on the difference image, the image quality is degraded. However, there is no problem in the monitoring control for monitoring the change of the apparatus state, the presence or absence of a person, etc.

Next, the operation of the first embodiment will be described with reference to FIG. The operation at the time of starting the still image transmission device will be described. When the present still image transmission apparatus is started, the transmission apparatus A1 transmits the reference image update control circuit 111
Outputs a reference image capture instruction to the write control circuit 103, and the write control circuit 103
04 is switched to the input of the reference image memory 105. Then, the television camera 101 and the A / D converter 102
The image data fetched through is written into the reference image memory 105. The reference image update control circuit 111 extracts the reference image data from the reference image memory 105 and transmits the image to the communication line L1 using the transmission circuit 110. In the receiving device B1, the reference image update control circuit 119 writes the reference image data received by the receiving circuit 112 into the reference image memory 115.

Next, the operation of the present still image transmitting apparatus when transmitting a still image will be described. In the transmission device A1, the write control circuit 103 sets the changeover switch 104 to the latest image memory 10
6 side, TV camera 101, A / D converter 10
2 is written to the latest image memory 106. Next, a subtractor 107 takes a difference between the images in the latest image memory 106 from the reference image memory 105 and outputs difference image data to a difference data reducer 108, and the difference data reducer 108 The information amount of each pixel is reduced by dividing the pixel data by a predetermined numerical value (N). Then, the JPEG compressor 109 performs image compression by the JPEG method on the difference image output from the difference data reducer 108,
The compressed image data is transmitted to the communication line L1 using the transmission circuit 110. The receiving device B1 converts the image data received by the receiving circuit 112 into a JPEG decompressor 11
3 is input. The JPEG decompressor 113 decompresses the input image data according to the JPEG method, and outputs the decompressed image data to the difference data decompressor 114. The difference data restorer 114 restores difference image data by multiplying each pixel data by a predetermined numerical value (N). Then, the obtained difference image data is added to the image data in the reference image memory 115 by the adder 116 to reproduce the image data, and the D / A converter 117
Is converted to an analog signal, and an image is displayed on the CRT 118.

According to the first embodiment, the difference data reducer 108 divides each pixel data of the difference image obtained by the subtracter 107 by 2 into 1 bit, and divides by 4 into 2 bits to obtain 2 bits. The amount of change of one pixel of the difference image can be reduced. For this reason, the change point difference is reduced by the JPEG compression feature described above, and the compression rate when the difference image is JPEG-compressed thereafter can be increased, and the data amount of the difference image transmitted to the communication line can be reduced. it can.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram of a still image transmission device according to the second embodiment. Components corresponding to the components shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In the first embodiment, a change amount constant 201 is connected between the subtractor 107 and the difference data reducer 108 of the transmission device A2 of the still image transmission device. Change amount determiner 201
When the value of each pixel data of the difference image input from the subtracter 107 is smaller than a predetermined value, it is determined that the change amount is small and can be ignored, and the value is replaced with 0. Here, features of the second embodiment will be described. This transmitting apparatus A2 is different from the first embodiment in that, with respect to the difference image data obtained by the subtractor 107, the change amount determiner 201 sets the data having a small change amount in the difference of each pixel to 0 as no change, thereby setting the difference to 0. Has also reduced the amount of information.

Next, the effects of the above features will be described with reference to FIG. 4 showing an example of a difference image. 4C is a difference image obtained from the reference image A and the latest image B described in FIG. 2, and E is a difference obtained by replacing data having a change amount of 10 or less in each pixel of the difference image C with 0 as no change. An image F is a difference image obtained by dividing each pixel of the difference image E by four. When the difference between adjacent pixels in the third row of the difference image F is calculated from the first column, the difference is 0, 0, 0, 7, 3. The difference image F is shown in FIG.
When the difference between adjacent pixels is smaller than that of the difference image D, the compression effect is higher than that of the difference image D when JPEG compression is applied. In addition, the image quality is degraded because a portion having a small amount of change is set to 0 as no change, but there is no problem in monitoring and controlling the change in the state of the apparatus, the presence or absence of a person, and the like.

Next, the operation of the first embodiment will be described with reference to FIG. First, an operation at the time of starting the still image transmission device will be described. When the still image transmission apparatus is started, in the transmission apparatus A2, the reference image update control circuit 111 outputs a reference image capture instruction to the write control circuit 103, and the write control circuit 103 sets the changeover switch 104 to the reference image. The input switches to the memory 105. Then, the image data captured through the television camera 101 and the A / D converter 102 is written in the reference image memory 105. The reference image update control circuit 111 extracts the reference image data from the reference image memory 105 and transmits the image to the communication line L1 using the transmission circuit 110. In the receiving device B2, the reference image update control circuit 119 writes the reference image data received by the receiving circuit 112 into the reference image memory 115.

Next, the operation of the present still image transmission apparatus during still image transmission will be described. In the transmission device A2, the write control circuit 103 sets the changeover switch 104 to the latest image memory 10
6 side, TV camera 101, A / D converter 10
2 is written to the latest image memory 106. Next, the subtracter 107 takes the difference between the images in the latest image memory 106 from the reference image memory 105 and outputs the difference to the change amount determiner 201. The change amount determiner 201 sets the portion where the change amount of each pixel is small in the difference image to 0, and outputs the difference image data to the difference data reducer 108. The difference data reducer 108 determines a predetermined numerical value (N) for each pixel data of the input difference image.
, The information amount of each pixel is reduced. And JP
JPEG compression is performed by the EG compressor 109 and data is transmitted to the communication line L1 using the transmission circuit 110. In the receiving device B2, the data received by the receiving circuit 112 is expanded by the JPEG expander 113, and the difference data restorer 114 multiplies each pixel data by a predetermined numerical value (N) to restore the difference image data. Then, the obtained difference image data is added to the image data in the reference image memory 115 by the adder 116 to reproduce the image data, converted to an analog signal by the D / A converter 117, and displayed on the CRT 118.

According to the second embodiment, since the data of the pixel having a small amount of change is regarded as not changing and is set to 0, only the portion where the image shown in the first embodiment has greatly changed can be extracted. JPEG to be done after this
The compression ratio of the compression can be further increased as compared with the first embodiment, and the data amount of the differential image transmitted to the communication line can be further reduced.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram of a still image transmission device according to the third embodiment. Components corresponding to the components shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In the third embodiment, the reference image update control circuit 1 provided in the transmission device A3 of the still image transmission device
11, a reference image update timer 301 is connected. The reference image update timer 301 is a reference image constant period update requesting unit that requests the reference image update control circuit 111 to update the reference image data at a constant period.

Next, the operation of the third embodiment will be described with reference to FIG. Here, the operations described in Embodiments 1 and 2 are omitted. The reference image update timer 301 outputs an update request to the reference image update control circuit 111 at regular intervals. Upon receiving the update request, the reference image update control circuit 111 outputs a reference image capture instruction to the write control circuit 103. Thereafter, similarly to the start-up operation described in the first and second embodiments, the transmitting device A3 fetches the reference image data, performs the updating process and transmits the data to the communication line L1, and the receiving device B3 performs the reference image data. It performs data reception and update processing.

According to the third embodiment, the reference image obtained by the transmitting device and the receiving device at the time of startup is obtained after the monitoring target image has changed greatly once, such as when the brightness or weather changes with time. In the difference image, the amount of change in each pixel increases, the difference efficiency decreases, and the amount of data to be transmitted increases.However, by updating the reference images of the transmitting device and the receiving device in a fixed cycle, a large change in the image is prevented. Even if there is, the differential efficiency can be increased.

Embodiment 4 Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram of a still image transmitting apparatus according to the fourth embodiment. Components corresponding to the components shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In the fourth embodiment, the input of the data amount measuring device 401 is connected to the output of the JPEG compressor 109 provided in the transmitting device A4 of the still image transmitting device, and the output of the data amount measuring device 401 is used as a reference image update control circuit. 111
Connect to The data amount measuring device 401 measures the data amount of the difference image compressed by the JPEG compressor 109, and instructs the reference image update control circuit 111 to update the reference image when it is determined that the data amount is larger than a certain value. Data amount measuring means.

Next, the operation of the fourth embodiment will be described with reference to FIG. Here, Embodiments 1 and 2
The operation described in step is omitted. The data amount measuring device 401
The data amount of the difference image compressed by the JPEG compressor 109 is measured. When the measurement result exceeds a certain value, the data amount measuring device 401 controls the reference image update control circuit 1
11 to output an update request. When the reference image update control circuit 111 receives the update request, the write control circuit 1
03, an instruction to take in a reference image is output. After that, similar to the operation at the time of startup shown in Embodiment 1,
The transmitting device A4 fetches the reference image data, performs the updating process and transmits the data to the communication line L1, and the receiving device B4 performs the receiving and updating process of the reference image data.

According to the fourth embodiment, the data amount of the image data transmitted to the communication line can be constantly monitored, and a large change in the monitored image can be determined based on the increased data amount. The reference image of the apparatus and the receiving apparatus can be updated efficiently, and the difference efficiency can be increased.

Embodiment 5 Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a block diagram of a still image transmitting apparatus according to the fifth embodiment. Components corresponding to the components shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In the fifth embodiment, the input of the change amount measuring device 501 is connected to the output of the change amount determining device 201 provided in the transmitting device A5 of the still image transmission device.
1 is connected to the reference image update control circuit 111. The change amount measuring device 501 measures the total change amount obtained by summing up the change amounts of the respective pixels from the change amount judgment device 201, and when the total change amount is larger than the previous total change amount, the reference image update control circuit 111. Is a change amount measuring means for instructing a reference image to be updated.

Next, the operation of the fifth embodiment will be described with reference to FIG. Here, Embodiments 1 and 2
The operation described in step is omitted. The change amount measuring device 501 measures the total change amount obtained by summing up the change amounts of the respective pixels, and when the change between the latest image and the reference image is large, that is, when the total change amount is larger than the previous total change amount. An update request is output to the reference image update control circuit 111. Upon receiving the update request, the reference image update control circuit 111 outputs a reference image capture instruction to the write control circuit 103. Thereafter, similarly to the operation at the time of startup described in the first embodiment, the transmitting device A5 fetches the reference image data, performs the update process and transmits the data to the communication line L1, and the receiving device B5 transmits the reference image data. Perform reception and update processing.

According to the fifth embodiment, since the change amount of each pixel of the difference image created by the subtractor and the change amount determiner is examined, it can be determined that the monitoring target image has greatly changed. It is possible to efficiently update the reference images of the apparatus and the receiving apparatus, and to increase the difference efficiency.

[0034]

As described above, according to the first aspect of the present invention, a difference image between the latest image captured from the imaging means and the reference image which is the same as the still image on the receiving device side is created, and the difference image is generated. A transmitting device that performs processing for reducing the amount of data for each pixel, performs image compression by the JPEG system, and transmits the image to the communication line, and performs image expansion and restoration processing on the image received via the communication line by the JPEG system To restore the difference image and add the difference image to the reference image, which is the same still image as the transmitting device side, to reproduce the latest image and to display on the display means. The data amount of the differential image transmitted to the communication line can be reduced, and the differential efficiency at the time of generating the differential image can be increased, thereby enabling monitoring control using a low-speed line. There is an advantage that it is possible to realize the image transmission in a short time the stem.

According to the second aspect, the transmitting device includes: a latest image memory for storing the latest image data based on the output signal from the image capturing means; A reference image memory for storing as reference image data, reference image update control means for performing control for updating the reference image data of the reference image memory, the latest image data of the latest image memory, and the reference image of the reference image memory Subtraction means for taking the difference from the data and outputting the difference image data; difference data reduction means for receiving the difference image data and calculating each pixel data of the image to reduce the value of the difference; and the reduced difference image JPEG compression means for applying JPEG compression to data,
A transmitting circuit for transmitting the image data from the PEG compression means to the receiving device; a receiving circuit receiving the image data from the transmitting device; and a JPEG decompressing means for decompressing the received image data by JPEG. And a differential data restoring unit that receives the decompressed image data, calculates for each pixel data of the image, and restores the differential image data reduced by the differential data reducing unit on the transmitting device side, and the transmitting device side A reference image memory for storing the same still image as reference image data, reference image update control means for performing control for updating the reference image data of the reference image memory in the same manner as the transmission device side, and a reference image memory of the reference image memory. Reference image data and difference image data restored by the difference data restoration unit And a display means for displaying the same still image as the image picked up by the image pickup means based on the output signal of the addition means, so that the transmission apparatus capable of achieving the effect of the first invention is provided. And a receiving device can be provided.

According to the third invention, the value of each pixel data indicated by the difference image data output from the subtraction means is set between the predetermined value between the subtraction means and the difference data reduction means in the transmission device. When the difference is small, it is determined that the amount of change is small and can be ignored, and the amount of change in the difference image data is further reduced. It can be considered that there is no change, whereby only the portion where the image has changed greatly can be extracted, and the compression rate of the JPEG compression performed thereafter can be further increased, and therefore the data amount of the differential image transmitted to the communication line can be reduced. The effect of being able to further reduce is obtained.

According to the fourth invention, in the transmission device,
Since the reference image update control unit requests the reference image update control unit to update the reference image data at a constant period, the reference image is updated at a constant period. In this case, the effect of increasing the differential efficiency can be obtained.

According to the fifth aspect of the present invention, in the transmitting apparatus, J
Since the data amount of the PEG-compressed differential image is measured and it is determined that the data amount is larger than the predetermined data amount, the reference image update control unit is provided with a data amount measurement unit that instructs the reference image update unit to update the reference image. The data amount of the image data transmitted to the communication line can be constantly monitored, and a large change in the monitored image can be determined based on the increase in the data amount, whereby the reference image can be updated efficiently and the difference efficiency can be reduced. The effect of being able to increase is obtained.

According to the sixth invention, in the transmission device,
A total change amount obtained by summing up the change amounts of the respective pixels from the change amount determination unit is measured, and when the total change amount is larger than the previous total change amount, a change instructing the reference image update control unit to update the reference image. Since the amount measuring means is provided, it is possible to determine that the monitoring target image has significantly changed, so that the reference image can be updated efficiently and the difference efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram of a still image transmission device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing an example of image processing according to the first embodiment;

FIG. 3 is a block diagram of a still image transmission device according to Embodiment 2 of the present invention.

FIG. 4 is a diagram showing an example of image processing according to the second embodiment.

FIG. 5 is a block diagram of a still image transmission device according to Embodiment 3 of the present invention.

FIG. 6 is a block diagram of a still image transmission device according to Embodiment 4 of the present invention.

FIG. 7 is a block diagram of a still image transmission device according to Embodiment 5 of the present invention.

FIG. 8 is a block diagram of a conventional video signal processing device.

[Explanation of symbols]

101 television camera (imaging means), 102 A / D converter, 103 writing control circuit, 104 changeover switch,
105 reference image memory, 106 latest image memory, 107 subtractor (subtraction means), 108 difference data reducer (difference data reduction means), 109 JPEG compressor (JPEG compression means), 110 transmission circuit, 11
1,119 reference image update control circuit (reference image update control means), 112 reception circuit, 113
JPEG decompressor (JPEG decompressor), 114 differential data decompressor (differential data decompressor), 115 reference image memory, 116 adder (adder), 117
D / A converter, 118 CRT (display means), 201
Change amount determination unit (change amount determination unit), 301 Reference image update timer (reference image constant period update request unit), 401 Data amount measurement unit (data amount measurement unit), 501 Change amount measurement unit (change amount measurement unit) , A
Reference image, B latest image, C-F difference image,
A1 to A5 transmitting device, B1 to B5 receiving device, L1
Communication line.

Claims (6)

[Claims] 1. A still image transmitting apparatus comprising: a transmitting apparatus for compressing a still image input as an analog signal into digital data and transmitting the digital data; and a receiving apparatus for expanding received still image data and displaying it on a display means. The transmitting device creates a difference image between the latest image captured from the imaging means and a reference image that is the same still image as the receiving device, and reduces the amount of data for each pixel with respect to the difference image. And the compression rate increases as the amount of change from one pixel to the surrounding pixels decreases.
The image is compressed by the system and transmitted to the communication line, and the receiving device converts the image received through the communication line into a JPE
The difference image is restored by performing the image expansion and restoration processing by the G method, and the difference image is added to the reference image which is the same still image as that of the transmission device side, so that the latest image is reproduced and displayed on the display means. A still image transmission device, characterized in that: 2. A transmitting apparatus, comprising: a latest image memory for storing latest image data based on an output signal from an image pickup means; and image data from the image pickup means as reference image data of a still image, which is the same as that on the receiving apparatus side. A reference image memory; reference image update control means for performing control for updating reference image data in the reference image memory; and a difference between the latest image data in the latest image memory and the reference image data in the reference image memory. Subtraction means for outputting the difference image data; difference data reduction means for inputting the difference image data to calculate each pixel data of the image to reduce the value of the difference; and applying JPEG compression to the reduced difference image data JPEG compression means and the image data from this JPEG compression means A transmitting circuit for transmitting the image data from the transmitting device to the receiving device;
JPEG decompression means for G decompression, differential data restoration means for inputting the decompressed image data, calculating for each pixel data of the image, and reconstructing the difference image data reduced by the difference data reduction means on the transmission device side A reference image memory for storing the same still image as the transmission device side as reference image data, and reference image update control means for performing control for updating the reference image data of the reference image memory in the same manner as the transmission device side. Adding means for adding the reference image data in the reference image memory and the difference image data restored by the difference data restoring means; and a still image identical to the image captured by the imaging means based on the output signal of the adding means. 2. The still image according to claim 1, further comprising: display means for displaying Feeding apparatus. 3. When the value of each pixel data indicated by the difference image data output from the subtraction means is smaller than a predetermined value between the subtraction means and the difference data reduction means in the transmission device, a change occurs. 3. The still image transmitting apparatus according to claim 2, further comprising a change amount determining unit that determines that the amount of the difference image data is small and can be ignored and further reduces the data amount of the difference image data to give to the difference data reducing unit. . 4. The transmitting apparatus further includes a reference image constant cycle update requesting means for requesting the reference image update control means to update the reference image data at a constant cycle. Item 3. The still image transmission device according to Item 1. 5. A transmission device measures the data amount of a JPEG-compressed difference image and, when it determines that the data amount is larger than a predetermined data amount, instructs the reference image update control means to update the reference image. 3. The still image transmission device according to claim 2, further comprising a data amount measuring unit that performs the operation. 6. The transmitting device measures a total change amount obtained by summing up the change amounts of the respective pixels from the change amount determining unit, and when the total change amount is larger than the previous total change amount, the reference image update control unit. 4. The apparatus according to claim 3, further comprising a change amount measuring unit for instructing the reference image to be updated.
Item 3. The still image transmission device according to Item 1.