JPH02230883A - Still picture transmission terminal equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a still image transmission terminal device suitable for use in, for example, a still image transmission system or a terminal device such as Videotex.

[Summary of the invention]

The present invention is directed to a still image transmission terminal device suitable for use in a still image transmission system or a terminal device such as Videotex, which has a first video memory capable of storing image data of a predetermined pixel density. On the other hand, a second video memory capable of storing image data having a pixel density higher than the predetermined pixel density can be freely connected, and the storage area of the second video memory can be transferred to a predetermined number from the still image transmission terminal. The image data in the divided designated storage areas is sequentially read out, and the read image data for each designated storage area is supplied to the first video memory, and the images stored in the first video memory are read out sequentially. By compressing and transmitting the data, all image data stored in the second video memory is sequentially compressed and transmitted in a time-sharing manner in units of predetermined pixel density for the first video memory. By doing so, the memory section and the transmission section are separated, and a standard image transmitter can be used in common to transmit various types of image data with higher pixel density.

[Prior Art] As the transmission pit rate of telephone lines has improved and it has become possible to transmit still image data with a large amount of information in a relatively short period of time, still image data Various terminal devices for transmitting and receiving are being developed. FIG. 9 shows Videotex (interactive character and graphic information system) built on a digital telephone network as an example of a system using such terminal devices.
1) is a digital exchange, (2) is a communication line, (3a),
(3b)... are telephones, (4a), (4
b) . . . are terminal devices, (5a) and (5b) are input/output sources of still images such as video recorders, and (6) and (7) are information centers, respectively.

With Videotex on the digital telephone network, the transmission bit rate can be up to 64kbps for both uplink and downlink, so from the information center (6) or (7) to each terminal device (
In addition to transmitting image information to terminal devices (4a), (4b), . . . , image information can also be exchanged between terminal devices (4a), (4b), . . . in a relatively short time.

[Problem to be solved by the invention]

Recently, as input/output sources for still images, in addition to those that support standard pixel densities such as NTSC and PAL systems, SHR (Super
High Resolution) type electronic cameras and so-called HDTV (High Definition)
Input/output sources having image data having a pixel density higher than the standard pixel density and a total number of pixels are being developed, as seen in television receivers of the NTV system.

However, when connecting a high-definition still image input/output source having such high pixel density image data to a terminal device that sends and receives still image image data, the entire terminal device must be connected according to the pixel density. have to be rebuilt,
There are disadvantages in that it takes a long time to develop and the manufacturing cost is high.

Furthermore, some input/output sources for still images include, for example, 2000.
There are special devices such as those with 2000 pixels, and developing dedicated terminal devices for each of these special devices leads to high-mix, low-volume production, which deteriorates manufacturing efficiency and increases manufacturing costs. There is an inconvenience that the amount increases.

In view of the above, an object of the present invention is to propose a still image transmission terminal device that can transmit various types of image data with higher pixel density without significantly changing the overall configuration of the device.

The second type can also store image data with large pixel density.
The second video memory (23a) is freely connectable, and the still image transmission terminal (8a) is connected to the second video memory (23a).
A designated storage area (a) formed by dividing the storage area of a) into a predetermined number of
For example, the first block 81 to the fourth block B in FIG. 3A.
) is sequentially read out, and the read image data for each specified storage area is supplied to the first video memory (16), and the first video memory (16) is
．． 6), by compressing and transmitting the image data stored in the second video memory (23a), the entire image data stored in the second video memory (23a) is compressed into a predetermined pixel density unit for the first video memory (16). The data is sequentially compressed and transmitted in a time-division manner.

[Means to solve the problem]

As shown in FIG.
A still image transmission terminal (8a) having a video memory (16) of
According to the present invention, in order to connect a still image input/output source of higher definition having image data with higher pixel density, the second Only the video memory (23a) needs to be replaced with one that can handle the still image. If the pixel density is, for example, N times (N is a natural number of 2 or more) the predetermined pixel density of the first video memory (16), then the storage area of the second video memory (23a) is Split into specified storage areas. First, the image data in the first specified storage area is transferred to the first video memory (l6),
The image data stored in the first video memory (16) is compressed and encoded and transmitted, and similarly, the image data in the second to Nth designated storage areas of the second video memory (23a) are sequentially transferred to the second to Nth designated storage areas. The data is compressed and transmitted through one video memory (16).

Therefore, according to the invention, the first video memory (16
) can be used in common to transmit image data with various higher pixel densities.

〔Example〕

Hereinafter, one embodiment of the still image transmission terminal device according to the present invention will be described with reference to FIGS. 1 to 7.

In this example, the present invention is applied to a terminal device of a still image transmission system that transmits still image signals via a communication line.
In FIG. 1, parts corresponding to those in FIG. 9 are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 1 shows a still image transmission system of the present invention.
In the figure, it is assumed that still image image data is compressed and encoded and transmitted from the terminal device (4a) to the terminal device (4b) via the communication line (2), the digital exchange (1), and the communication line (2). These terminal devices (4a) and (4b) are equipped with standard transmitters (8a) and (8b), respectively, and these standard transmitters (8a) and (8b) have the same configuration and are NTS
It is possible to send and receive image data corresponding to standard format video signals such as C format or PAL format. In this case, the communication line (2) is ISDN (Integrated Network).
services digital network), high-speed digital line, DDX (digital data exchange) network (there are two types: DDXC and DDXP)
etc. are possible.

Furthermore, it is also possible to use an analog telephone line or a wireless transmission line instead of the digital communication line (2).

To explain the configuration of the standard transmitter (8a), (9) is a central processing unit (CPU), ROM (11), and RAM.
(12) is a microcomputer consisting of a microcomputer, (13) is a CP consisting of a data bus, two address buses, a control bus, etc.
A system bus of U (10) is shown, and R O M (11) and R A M (1
2) Connect.

This microcomputer (9) is connected to this terminal device (4a).
).

(14) is the keyboard, (15) is the keyboard (14)
and an input/output circuit (1) connecting the system bus (13) and the system bus (13).
6) shows the first video signal RAM (VRAMI) consisting of a standard capacity frame memory;
The input/output terminal of this VRAMI (16) is connected to the system bus (13), assuming that image data of P dots (horizontal direction) and XQ dots (vertical direction) pixels can be stored in 1 (16). Generally, P=768 and Q=480.

Further, (17) indicates a write/continuation control circuit, (18) indicates an address signal generation circuit, and the microcomputer (
9) generates the first and second write/success pulses J and J2 by controlling the write/success control circuit (17) via the system bus (13), and generates the address signal generation circuit (18). ) to generate first and second address signals ADRI and ADRz. supplying a first write/sequence pulse J1 and a first address signal ADR, respectively to VRAMI (16);
The second write/sequence pulse J2 and the second address signal ADRt are respectively sent to the attached second video signal RAM (VRAM2) (23) via an input/output circuit (21) to be described later.
a).

Further, (19) indicates a timing circuit, and this timing circuit (19) generates a synchronization signal corresponding to a vertical synchronization signal and a horizontal synchronization signal of the video signal to an address signal generation circuit (18).
), and the address signal generation circuit (18) generates the above-mentioned first and second address signals AD corresponding to pixels at predetermined coordinates in the horizontal and vertical directions using the synchronization signal as a reference.
H. and produce A D R 2.

(20) indicates a communication control device connected between the communication line (2) and the system bus (13), and this communication control device (20) controls the protocol and transmission of still image signals of the communication line (2). It operates as a communication interface depending on the speed.

In addition, (21) and (22) are the system bus (13), respectively.
), and in this example, through the input/output circuit (21), a capacity of four times the standard,
R for the second video signal consisting of a frame memory having
Connect the human output terminal of AM (VRAM2) (23a) and the system bus (13). This VRAM2 (23
In a), image data having a number of pixels of 2P dots (horizontal direction)×2Q dots (vertical direction) can be stored. In the tree example, the standard transmitter (
8b) is also connected to V R A M 2 (23b) having the same capacity as V R A M 2 (23a). Also,(
24) is SHR (Super High Ros)
This SHR camera (2
4) generates a video signal with twice the pixel density in the horizontal and vertical directions and four times the overall pixel density (the total number of pixels is also four times) as compared to the standard method. Then, the video signal of one still image generated by this SHR camera (24) is sent to V via an analog/digital (A/D) converter (25).
Write to RAM2 (23a). Also, (27) is S
V R A M 2 (23
By supplying the image data written in a) to the SHR monitor (27) via the digital/analog converter (26), a high-definition image with four times the standard pixel density is displayed on the SHR monitor (27). ) will be displayed.

In addition, as shown by the broken line in FIG. 1, this standard transmission a (aa
) via the input/output circuit (22) of the system bus (13)
A digital/analog converter (28) and a standard monitor (29) may be connected to. In this way, the standard monitor (2
9), a still image corresponding to the standard pixel density image data stored in the V RAM 1 (16) can be displayed on the standard monitor (29).

The flowchart in Figure 2 shows the operation when transmitting the image data of one still image, which has four times the standard pixel density, captured by the SHR camera (24) in the example in Figure 1 to the terminal device (4b) side. To explain with reference to the terminal device (4a)
The microcomputer (9) on the side has its RAM (
After initializing the value of the variable n written in 12) to 1, image data with 4 times the pixel density corresponding to the still image captured by the SHR camera (24) is transferred to V R A M 2.
(23a) (Step (90) in Figure 2)
, (91)). In this case, as shown in FIG. 3A,
Image data with a pixel count of 2Px2Q dots is written to M2 (23a), so this storage area is
It is divided into four blocks, ie, a first block B1 to a fourth block B4, each having the number of pixels of XQ dots. Therefore, the number of pixels in each of the first block 81 to fourth block B4 is equal to the number of pixels in the entire storage area of V RAM 1 (16) shown in FIG. 3B.

Then, the microcomputer (9) runs the step (92
), VRAM 2 determined by the value of variable n
(23a) nth block (currently the first block B,)
After writing the image reward data to VRAMI (16) and incrementing the value of the variable n written to R A M (12) by 1 in step (93), the data in VRAMI (16) is written in step (94). The image data stored in the image data is compressed and encoded.

The block encoding method (8 dap) is used as a compression encoding method.
tive Block Truncation
An example of the case where the block coding method (A B T C method) is used will be explained with reference to FIGS. For example, a screen (29a) consisting of horizontal P dots (pixels) x vertical Q dots
, the basic block Bij (1≦
i≦M, 1≦j≦N) (Fig. 4). and,
To compress and transmit this screen data, first the basic block Bl+ is compressed and encoded and transmitted, then the basic blocks B,
2, . . . B, N, B2, . . . are compressed and encoded and transmitted. In order to compress and encode each basic block, the basic block (Fig. 5A) must be
1/4 block (4x4 block) obtained by dividing (
After introducing the concept of 1/16 block (2 x 2 block) (Fig. 5 C) obtained by dividing the basic block into 16 parts (Fig. 5 B) and the basic block, the encoding modes shown in Table 1 are combined. used.

Table 1 Encoding mode Also, the processing block unit in the basic block is expressed as rmnj, where m indicates mXm block,
n indicates a position within the basic block shown in FIG. 6B. When encoding the processing block rmnJ using each encoding mode shown in Table 1, a "mode flag" shown in FIG. 6A is added before the data information of the basic block. this"
The receiving side can decode the image data using the "mode flag" information.

FIG. 7 shows an encoding algorithm of the bronc encoding method for compression encoding an 8×8 basic block by combining the above-mentioned encoding modes. In FIG. 7, ε and ε2 each indicate the standard deviation of the data values of all pixels of the processing block, and threshold values E and Ez each indicate the allowable value of the standard deviation. In addition, a0 and a1 are pixel data values at the upper left corner and upper right corner, respectively, of dividing the processing block into four equal parts, and d
l+d2 and d, respectively at a(++, that is, a type of variation in data values, and threshold values D + , D 2 and D3 respectively indicate allowable values for variation in data values. Therefore, the standard deviation ε1 and the variation d, If it is smaller than the tolerance value, the process proceeds from step (100) to step (104) and is processed in 88 mode, in which all 64 pixel values of the basic block are transmitted as the same value (for example, average value). , standard deviation ε, or variation d1 are each larger than the allowable value, the process moves to step (105), and step (108) is performed depending on whether the standard deviation ε2 of the 4×4 block is smaller or larger than the threshold value E2. )
Proceed to the following steps or step (112). Step (1
12) The following shows the code of a 2×2 block. First, in step (113), the dispersion d, is determined. If the dispersion d3 is smaller than the threshold value D, then step (
Step (114) proceeds to step (115), and if the variation d, is greater than the threshold value D, step (11
4), proceed to step (116).

By sequentially compressing and encoding each basic block Bij in this way, all the image data stored in VRAMI (16) can be compressed and encoded.

In addition, the software that executes the compression encoding algorithm as shown in the example in Figure 7 is already available in NTSC and PA formats.
Software developed for compressing and encoding image data in standard formats such as the L format can be used as is. Therefore, there is an advantage that there is no need to develop new complicated compression encoding software.

Next, in step (95) of FIG. 2, the microcomputer (9) uses the compressed and encoded image data and V
A code indicating the first block B1 of RAM 2 (23a) is supplied to the communication control device (20). As a result, the compression-encoded image data and the code indicating the block are transmitted to the other party's terminal device (4b) via the communication line (2), digital exchange (1), and communication line (2) in a short time. Ru. In the terminal device (4b), standard transmission 1
(8b) decodes the received image data and converts the decoded image data to V R A M 2 (23b)
is written into the first block formed by dividing the storage area into four parts.

Then, in step (96), the microcomputer (9) checks whether the value of the variable n stored in its RAM (12) exceeds 4 or not. When the value of the variable n is 4 or less, the transmission of the image data from the n-th block 87 to the fourth block B4 of V R A M 2 (23a) has not been completed, so the microcomputer (
The operation 9) repeats steps (92) to (95) again. The image data thus stored in V R A M 2 (23a) is stored in the first block B. →・・・→
V RAM 1 (16
) are compressed and encoded, respectively, and sent to the terminal device (4b
) side. In this case, in the terminal device (4b), the received image data is decoded and sequentially transferred to the VRA.
The data is written to the first block B of M2 (23b) →...→the fourth block B4. And V.R.A.M.
2 When the transmission of all image data in (23a) is completed, the variable n
Since the value of is 5, the microcomputer (9
) stops at step (96).

As described above, according to this example, by using the standard transmitter (8a) for the NTSC system, etc., it is possible to transmit image data having a pixel density four times that of the normal one. Therefore, there is no need to develop a new transmission section and the terminal device (4a
) can be developed in an extremely short time, and the standard transmission m (8a), which is mass-produced at low cost, can be used as is, so there is an advantage that the manufacturing cost of the terminal device (4a) is low. Furthermore,
This example has the advantage of being able to handle image data having various pixel densities by simply changing the capacity of the VRAM 2 (23a) and being highly expandable.

Although the above-mentioned embodiment shows the case where the storage capacity of VRAM 2 (23a) is an integral multiple of the storage capacity of VRAMI (16) of the standard transmitter (8a), the present invention
The storage capacity of AM 2 (23a) is its V RAM
This can be applied even when the storage capacity is not an integral multiple of the storage capacity of 1 (16). To explain an example of this case, V R A
As shown in FIG. 8A, instead of M 2 (23a), (
A third video signal RAM (VRA
M3) (30a) is used.

Then, the storage area of the V RAM 3 (30a) is divided into first to fourth blocks B4, each having a storage capacity of PXQ dots, and a fifth block B, having a fractional storage capacity. By dividing in this way, the first block 81 to the fourth block B4 of VRAM 3 (30a) are divided into VRAM 1 of FIG. 8B.
(16), it can be compressed and encoded and transmitted. In this case, the image data of the fifth block B of VRAM 3 (30a) is transferred to VRAMI (16) in a predetermined order.
), this VRAMI (16
A surplus portion (31a) remains in the storage area of ), and data with all values of 0, for example, is written into this surplus portion (31a). Then, by compressing and encoding the image data of this VRAMI (16) and transmitting it, the V RAM
The fractional image data accumulated in the fifth block B of 3 (30a) is also transmitted.

In addition, in FIG. 1, by providing a so-called down converter that converts the SHR signal into a standard signal such as an NTSC signal between the V R A M 2 (23a) and the input/output circuit (21), the V R A M 2 (23a) is converted to standard signal image data and VRAMI (1
6) may be written. In this case, the standard transmitter (8b) and VRAM2 (
23b) is provided with an up-converter for converting the standard signal into an SF{R signal.

In addition, in the above embodiment, the terminal device (4b) of the other party
is equipped with a standard transmitter (8b) like the terminal device (4a), but the terminal device (4b) on the other side is SHR (SHR).
The present invention is applicable even when the transmitter is equipped with a transmitter compatible with higher resolution. In this case, first, V RAM 1 (16
), in order to transmit standard-formed image data that has been properly stored in ) to the terminal device (4b), the terminal device (4a) must, in the communication protocol exchanged before sending the compression-encoded image data, A code indicating that the image data has standard density is transmitted to the terminal device (4b). Accordingly, SHR-compatible terminal equipment (
In step 4b), the received and decoded image data is enlarged four times by zero-order interpolation and written into the built-in frame memory.

On the other hand, SHR-compatible VRAM2 (2) of the terminal device (4a)
3a) to the terminal device (4b) via the V RAM 1 (16).
) is a code that indicates that the image data has four times the standard pixel density in the communication protocol.
). In response to this, the SHR compatible terminal device (4b) writes the received and decoded image data as is into its built-in frame memory.

In this way, before sending compression-encoded image data, a code indicating the pixel density of the sending terminal is transmitted, and the receiving terminal reduces (thinning, etc.) or enlarges (0-order interpolation) the decoded image data. etc.) and writing it into memory, image data can be sent and received even between terminal devices that support different pixel densities.

As described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various configurations may be adopted without departing from the gist of the present invention.

(Effects of the Invention) According to the present invention, the storage area of the second video memory is divided into a predetermined number of areas, and image data for each divided area is sequentially supplied to the first video memory of the still image transmission terminal. However, since the image data in this first video memory is compressed and transmitted, and the memory section and the transmission section are separated, a standard image transmitter is commonly used to transmit various higher pixel data. There is an advantage in being able to transmit image data with density.

Therefore, it is possible to flexibly handle image data having various pixel densities, and to reduce the manufacturing cost of a still image transmission terminal device that can handle various pixel densities.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the still image transmission terminal device of the present invention, FIG. 2 is a flowchart showing the operation of the example in FIG. 1, and FIG. 3 is a line diagram for explaining the operation of the example in FIG. 1. 4 to 7 are diagrams for explaining the compression encoding of the embodiment, FIG. 8 is a diagram for explaining another embodiment of the present invention, and FIG. 9 is a diagram for explaining the compression encoding of the embodiment. It is a block diagram which shows an example. (8a) is a standard transmitter, (9) is a microcomputer, (16) is the first video signal RAM (VRAM1
), (20) is the communication control device, (23a) is the second video signal RAM (VRAM2), (24) is the SHR
It's a camera.

Claims (1)

[Scope of Claims] A still image transmission terminal having a first video memory that can store image data with a predetermined pixel density, and a second video memory that can store image data with a pixel density greater than the predetermined pixel density. The video memory of the second video memory is freely connectable, and the still image transmission terminal sequentially reads out image data in a designated storage area obtained by dividing the storage area of the second video memory into a predetermined number of parts, and reads out the image data of the designated storage area that has been read out. supplying image data for each storage area to the first video memory;
By compressing and transmitting the image data stored in the first video memory, all the image data stored in the second video memory is sequentially transmitted in units of predetermined pixel density for the first video memory. A still image transmission terminal device characterized in that the still image transmission terminal device compresses and transmits in a time-division manner.