FR2620543A1 - Image display peripheral for a data communications network for digital information transmission and terminal incorporating the structure of such a peripheral - Google Patents

Abstract

The peripheral comprises: an interconnection bus 1; a management and calculating unit 2 connected to this bus; a read-only memory 3, connected to the bus, containing the reception software, software for memory storage and/or visual display of the images received from the data communications network; a random-access memory 8 connected to this bus; a video (random-access) memory 7 connected to this bus for processing and storing the image digital information received from the bus; a network interface 9, for the peripheral interface with the data communications network, this interface also connected to the bus so as to allow exchange of information between the network and the management and calculating unit and ocassionally the input of additional specific software into the read-only memory; a video interface 10 receiving, at its input 10a, image digital information from the video memory and feeding out, on at least one output 5a, 6a, video signals to at least one visual display module; and a logic unit 14 for monitoring the operations of the peripheral, connected to the bus and to the video memory.

Description

"Image viewing device for network tee
transmission of digital information and
terminal incorporating the structure of such a periphery
than"
The present invention relates to the transmission and visualization of images using a telematic network for the transmission of digital information, in particular at relatively slow speed, for example of the order of 1200 baud, in particular the integrated "MINITEL" network. to the telephone network.

 It relates to an image viewing device, or imaging device, connected to a terminal connected to such a telematic network, in particular a MINITEL network, and also to a terminal in which the structure of such a device is incorporated.

 Complex systems are known, for viewing images or for imagery, in particular for digital imagery, using networks, in particular local networks, very efficient, at very high transmission speed of several megabauds or even several tens of megabauds. .

 On the other hand, the invention aims to produce a relatively simple peripheral, as well as a terminal incorporating such a peripheral, capable of being connected to a telematic network, in particular the Minitel network, even at low transmission speed, for example from the order of 1200 bauds (maximum).

 Now considering more particularly the Minitel and its network, the invention proposes to extend their graphic possibilities.

Indeed, at present, the Minitel does not have a sufficient level of resolution and definition to allow imaging, because it is limited to a display mode on its screen module which is only semi-graphic, the fact that it only has 128 mosaic shapes (of which 64 are joined and 64 are not joined), each shape resulting from the division of a matrix of 8 by 10 pixels or image elements into six boxes of different dimensions (see the standard entitled "Technical Specification for the Use of Minitel 1 B", abbreviated
STUM, for example pages 101 and 102 of the edition of
November 1986 Teletel from the French Ministry of Posts and Telecommunications).

 On the other hand, the definition of the Minitel is limited to eight levels of gray (or eight colors in the case of color screen modules), as specified on page 32 of the said edition of the STUM.

We also know that Minitel devices have, in their sophisticated version, a five-pin DIN type computer socket, to which it is possible to connect a peripheral, or a chain of peripherals connected in series, allowing specific applications , the Minitel set (with its screen module, which decodes and displays the information it receives, its keyboard module, which allows the user to enter information, its peri-computer socket module, which provides the transmission of information between the Minitel and a peripheral, and the modem module, which carries out the transmission of information between the Minitel and a database) and of the telematic network being governed by Technical Specifications for the Use of the Minitel Network, for short STURM (see the August 1986 DAII edition of
French Ministry of Posts and Telecommunications).

 The problem which the invention aims to solve is to produce a peripheral (as well as a terminal incorporating the structure of such a peripheral) capable of connecting to the Minitel network or to another digital telematic network, in particular at low speed. transmission, in order to manage files comprising files which contain digitized images (that is to say whose pixels are digitally coded), to receive and store such files and to provide at least one video output for viewing the digital images it is receiving, or which it has previously received and which it has memorized, on at least one screen (Minitel screen, television set screen, video monitor screen for example), and this by means of independent pixels which can take a relatively high number of different values of gray or different colors, for example 16, 32, 64 or 128.

 To this end, the present invention essentially relates to an image display device for a telematic network for the transmission of digital information, characterized in that it comprises, in its structure, in combination: an interconnection bus; a management and calculation unit connected to this bus; a read-only memory, connected to the bus, containing the software for receiving, storing and / or viewing the images received from the telematic network; a random access memory connected to this bus; a video memory connected to this bus for processing and storing the digital image information received from the bus; a network interface, of the peripheral with the telematic network, interface also connected to the bus in order to allow the exchange of information between the network and the management and calculation unit and occasionally the entry in the RAM of specific additional software ; a video interface receiving on its input digital image information from the video memory and outputting r at least one output, video signals to at least one display module; and a logical device for controlling the operations of the peripheral, connected to the bus and to the video memory.

Advantageously:
- The peripheral also includes an autonomous power supply, able to save the information it contains in the event of interruption of the power supply by the external electrical network;
the management and calculation unit is a processor, in particular a microprocessor.

In a particular embodiment, the single display module or one of the display modules, connected to an output of the video interface, consists of the screen module of a device
Minitel, equipped with a video input socket, the peri-computer socket module of this Minitel device is connected to the network interface of the peripheral, and the keyboard module of the Minitel makes it possible to control reception, storage and viewing of 'images on the screen module of it.

 The subject of the invention is also a terminal constituted by the structure of a peripheral of the aforementioned type (but not according to the above-mentioned particular embodiment in which the peripheral is connected to a Minitel device), a screen module connected to said video interface and a control keyboard module connected to said bus.

 In a particularly advantageous embodiment, the aforementioned peripheral or terminal implements software which allows it to view the images contained in an image file whose pixels are digitized in ASCII code and in which each image is coded on several sub-files, the whole of which constitutes the H file of the complete image, each sub-file storing a matrix of pixels by rows and columns and the successive sub-files each containing digital information on the totality of the pixels of the image, but with increasingly fine grayscale or hue details.

 Advantageously, the gray level or the hue of the successive pixels is coded in the form of bytes, the first two bits of which contain information on the invariance or not of gray or hue of the subsequent pixels.

 The invention may, in any case, be well understood with the aid of the additional description which follows, as well as of the appended drawings, which supplement and drawings are, of course, given mainly by way of indication.

 Figures 1 and 2 illustrate, in the form of functional blocks, the units of a device according to the invention, respectively in the general case and in the case of its association with a Minitel device.

 FIG. 3 schematically represents the phases of the processing of the content of the successive sub-files arriving at the device of FIGS. 1 or 2, in the case where each image to be viewed or stored is contained in several sub-files comprising gray level details or of increasingly fine tint of the total image.

 According to the invention and more particularly according to that of its modes of application, as well as those of the embodiments of its various parts, to which it seems that there is reason to be given preference, proposing, for example, to produce an image viewing device for a telematic network for transmitting digital information or a terminal incorporating the structure of such a device, this is done as follows or in a similar manner.

Referring first to general Figure 1 and Figure 2 regarding application to the network
Minitel, we see that a device according to the invention comprises in combination:
- an interconnection bus 1 capable of interconnecting a certain number of units of the peripheral;
a management and calculation unit advantageously constituted by a microprocessor 2, for example from the 8051 family, from the companies INTEL or MATRA-HARRIS, which is connected to bus 1 and which performs the various operations on the digital information to be processed;
a video random access memory 7 intended for storing the digital image information received from the bus 1 and which is a fast memory (with short access time), for example of the TEXAS INSTRUMENTS TMS 4256-12 type;
- a read only memory or ROM memory 3 also connected to the bus 1 and which contains the resident program or software for viewing the images; this program manages the protocol, for example the "protocol" of the Minitel, the exchange system with the telematic network, such as the Minitel network, connected in 4 (fig.1) or 4b (fig.2), the presentation of the images on the viewing devices or screens connected in 5 and 6 (fig. 1) or in 5c and 6c (fig. 2), for example on the screen of a Minitel device connected in 5 or 5c and on the screen of a video monitor and / or a television set connected in 6 or 6c, and the resident application in particular for processing the images being stored in digital form in the video random access memory 7;
- a random access memory 8, also connected to the bus 1, and which can store, on the one hand, instructions and digital information coming from the microprocessor 2 and, on the other hand, a specific downloaded program (which depends on the application ) arriving from the telematic network connected in 4 or 4b;
a network interface 9 connecting the peripheral to the telematic network, for example the Minitel network, connected in 4 or 4b, this inferface 9 also being connected to bus 1 in order to allow the exchange of information between, on the one hand, the network and, on the other hand, the microprocessor 2 and possibly the RAM 8 for the entry into it of additional software downloaded for a downloaded application resulting in the viewing of images received from the network;
a video interface 10 receiving digital image information from its input 10a from the video memory 7 and outputting video signals to its outputs Sa and 6a to display devices, in particular to a Minitel device connected in 5 or 5c and to at least one video monitor or television set, connected to 6 or 6c, as indicated above.

 The peripheral also comprises a general electrical supply device 11 supplied, on the one hand, by a mains socket 12 and, on the other hand, by a backup socket 13 connected to a battery to maintain the electrical supply of the peripheral in network power failure in order to save the information contained in RAM 7 and 8.

 The device of FIGS. 1 and 2 also comprises a logic control unit 14 connected, on the one hand, to the bus 1 and, on the other hand, to the video random access memory 7 to control the latter as a function of information received from the microprocessor 2.

FIG. 2, which particularly relates to the case of a peripheral according to the invention connected to a Minitel device, is similar to FIG. 1, with the following modifications:
We first explained the connections.

 In particular, the interface 9 between the network and the Minitel comprises a male socket 4a, for the peri-computer female socket 4b of the Minitel, which is, as is known, a DIN socket with five female pins, and a male socket 4'a , for the female socket 4'b of any other peripheral device connected in series with the peripheral device according to the invention.

 Likewise, the sockets 5b and 6b of the device have been shown according to this FIG. 2 connected to a video socket 5c installed in the Minitel device and two video sockets 6c of video monitor or television set.

 The device of this FIG. 2 finally comprises two display panels 15 and 16 respectively intended for viewing the connected or unconnected state of the Minitel, depending on whether it is the indicator 15a or 15b which is lit, and for indication of the available images displayed depending on whether the indicator 16a or 16b or 16c ... is lit.

 We will now describe the operation of the device according to Figure 1 or 2 for storing and viewing images received through the network connected in 4 (Figure 1) or 4a, 4b (Figure 2) from a database with a specific image file to the application envisaged with a series of files, each advantageously consisting of several sub-files, in which the images are digitally coded.

 Assuming first of all that the pixels of each image are digitally coded on a single card, the digital information relating to an image called by the device arrives in it on the network interface 9, and is therefore available on the bus 1, at the same time as possibly a special application program for the intended application.

 The optional additional application program is introduced into the random access memory 8 and is added to the resident program which is stored in the read-only memory 3 to control the operation of the microprocessor 2.

 The microprocessor 2 processes (according to the program of the read only memory 3 and possibly of the random access memory 8) the digital information of images available on the bus 1 and controls, in particular under the effect of the logic control unit 14 of FIG. 2, the storage of digital image information in the video random access memory 7.

 Still under the control of the logic unit 14, the digital video information from the video memory 7 can be transmitted to the video interface 10 which supplies video signals usable on the screens connected to the sockets connected to the outputs 5a and 6a of the interface, in particular on a screen of a Minitel device connected to socket 5b.

 It will be noted that in the case of images arriving directly from the network, the interface 10 provides video signals which can be used in real time, that is to say as data is received.

 In addition, in certain cases, one or more images received previously can be kept in the video memory 7, the storage of these images being carried out in digital code, then the restitution of one or more stored images at the desired time. in the video memory 7, under the effect of the control of the unit 14 and via the video interface 10, to one or more screens.

In the particular case of FIG. 2, that is to say of a connection to the Minitel network, the peripheral can be implemented:
- either when the Minitel device is connected to the Minitel network (connected state), and this by a command from the network or the application; in this case, the application is managed entirely by the device or in part by it when a portion of the application software is downloaded to the RAM 8, that is to say transmitted to this memory by the network through the interface 9 and the bus 1;
- either when the Minitel is not connected to the Minitel network (local state), and this by typing, on the keyboard of the Minitel, a specific command identified by the device, and we can then transmit to the video interface 10 and therefore on the external display screens, the image or images stored in the video memory 7.

 In both states the user implements the device according to the invention by means of the keyboard of the Minitel device.

 Of course the read only memory 3 comprises, in the case of the embodiment of FIG. 2, software for managing the Minitel protocol, in accordance with the specifications described in the STUM, and it also has, on the one hand, a from a hardware point of view, a physical layer and, on the other hand, from a software point of view, an exchange systems layer, these two layers conforming to the specifications of the STURM (pages 43 and following for the physical layer and pages 17 and following for the exchange systems layer, in the above-mentioned edition of the STURM).

 We will now explain in more detail the operation of the device of FIG. 1 or of FIG. 2 in the case where the image file comprises, for each image, not a single file, but a series of sub-files each with information about the entire image, but with varying degrees of detail in terms of grayscale or hue.

 Such an embodiment is particularly advantageous, because it makes it possible to transmit and display very quickly a first item of information recorded on the first sub-sheet, or main sub-sheet, information limited as regards the details of gray or hue, additional information being requested successively only if the viewing of the first sub-file leads the user to desire additional details. On the other hand, if the user finds that he has already obtained from the first sub-file , or from the first sub-files, sufficient information, it does not call the subsequent sub-file or the subsequent sub-files, which reduces the total transmission time of an image; Similarly, if the information provided by the first sub-file shows the user that the image called is of no interest to him, he can stop the interrogation, and this after a reduced duration. This therefore results, in the latter two cases, in saving time and reducing billing for the transmission.

 In the case of such a particular embodiment with several sub-files, each sub-file comprises (as is the case for a single file per image) a matrix of image elements or pixels arranged in rows and in columns, for example 256 rows and 256 columns (each row therefore comprising 256 pixels).

 In addition, each pixel can have a number of gray levels or different colors, generally 2n values (n being a small positive integer).

 We will consider below the case of 16 values (n = 4), but of course the invention applies to a higher number (32,64,128) or possibly more reduced (8,4) of levels.

 The pixel coding implements in particular the ASCII code (American Standard Code for Information Interchange, that is to say American Standardized Coding for the Transmission of Information) and the digital transmission relates to a succession of bytes (group 8 bits). In particular in each byte, the first two bits may contain information concerning the invariance or variance of the gray level or of the hue of the subsequent pixels, and this in order to reduce the reading time of the bytes in the peripheral. We can thus foresee that, when the first two level bits are "10" or "11" r the five subsequent bits represent in binary code the number of subsequent pixels which have the same gray level or the same hue (this number can go up to 31) and which therefore constitute a packet. If the first two bits are "10" the packet only has "0", while, if the first two level bits are "11", the packet does not has only "1", which reduces the reading time for these two cases.

 On the other hand, if the first two bits of the byte are "01", it will be necessary to read the five subsequent bits representative then of gray level or hue and which are not all constituted by "0" or by "1" only, the gray level or hue varying from one pixel to another, these next five bits representing the gray level or hue of the pixel.

 Finally the last bit of the byte constitutes a parity bit (even).

 The first sub-file of the p sub-files simply indicates whether the level is greater than or equal to 8, that is to say between 8 and 15, on the one hand, or less than 8, that is to say between O and 8, on the other hand.

 The second sub-file specifies, in the first case, if the level is greater than or equal to 12, that is to say between 12 and 15, or even less than 12 (while being at least equal to 8), c 'is to say between 8 and 11; in the second case, this second subfiche specifies whether the level is greater than or equal to 4 (while being less than 8), that is to say between 4 and 7, or even less than 4, that is to say - say between O and 3.

 The third sub-file divides the uncertainty again by two by solving the levels 2,4,6,8,10,12 and 14, and finally the last file resolves the elementary levels 0,1,2,3, ... 14.15.

 We therefore see that, in this case, p is equal to n, the number of sub-records p being equal to the exponent n of the number 2n of possible levels of gray or hues.

 It will be noted that each sub-file includes a start code constituting a pagination and an end code of the sub-card.

 The read-only memory 3 of the device stores an algorithm for decoding and decompressing the bytes received on the interface 9 from the network on which the device and the database containing the image file are connected, so as to be able to allow storage in digital and in real time in the video memory 7 of the corresponding pixels, which are retransmitted either in real time, or possibly later, by the video interface 10 to the display screens.

Thanks to the invention, it is possible to receive and store in video memory 7 a number of pixels per image (for example 256 × 256 pixels) much greater than the 128 mosaic forms implemented by a device.
Classic Minitel; in the same way we can receive and store 16,32,64 and even 128 different gray values or colors, while the Minitel only allows to process 8 levels of gray or 8 colors, as indicated on page 32 of the aforementioned edition of the STUM standard.

 In FIG. 3, the functional diagram of the processing of the p successive sub-files has been explained in a peripheral according to FIG. 1 or 2.

 The peripheral begins, depending on the program stored in the read-only memory 3 and possibly introduced in the random access memory 8, to read, from the file, the number of sub-files that the sought-after image contains, that is to say the maximum number of sub-files it must analyze and display. It writes in memory 8 this number of sub-files, which is for example p.

 Then the device decodes the code of the "first" sub-file, that which distinguishes if the level is 8 or <8 when p = 4, sub-file indexed p (the following sub-files being indexed p-1, p -2 ,. .1), and it reads the first byte, namely the byte s (the following successive bytes being indexed s-1, s-2 ... 1) starting with the most significant bit, namely the bit of rank r which precedes the following bits of rank r-1, r-2, ... 1, that is to say at the head.

 Thus the peripheral will read and store in the video memory 7 successively all the bits of the first byte (indexed s) and, when the last bit of this byte has been read and written in video memory 7, it will pass to the next byte (s When the last byte (indexed 1) of the sub-record p has been read and written to video memory 7, the program of the peripheral commands the latter to call the sub-record pl to read and store it the successive bytes and so then for the successive sub-files up to the last file (indexed 1), the reading and the writing in memory of the last file ending the operation (unless, as indicated previously, the operator does not decides to stop viewing immediately after inspecting the first sub-file, indexed p, or the first sub-files p, p-1, p-2 for example).

 It will be noted that, for the sake of simplicity, on the flowchart of FIG. 3, as regards the reading of the bits of each byte, there is included the case where the coding of each sub-file does not include the characteristic that the first two bits of the byte (of ranks r and r-1) carry information on the invariance or variance of the gray level or the hue of the subsequent pixels.

In the case of the implementation of such a characteristic, it is necessary to modify the part of the flowchart between points A and B which relates to the reading of the bits, starting this one by reading the bits of rows r and r-1 (and not of the only bit of row r) and then providing for a three-way connection:
- the succession of the bits of rows r and rl is "10", then when the peripheral reads the following five bits and writes a number of "O" equal to the number (<31) that represents all of these five bits and we pass when reading the parity bit (rank 0),
the succession of the bits of rows r and r-1 is "1t", then the peripheral reads the following five bits and writes a number of "1" equal to the number (<31) that represents all of these five bits and we pass to the reading of the parity bit (of rank 0),
- the succession of the bits of ranks r and rl is neither "10" nor "~ 1", then the peripheral reads the bit of rank r-2 and writes it, then the bit of rank r-3 and the registered and so on until the parity bit (rank O).

 At the end of each of these three paths, we find ourselves at the point marked B on the flowchart in Figure 3.

 As indicated previously, instead of recording in video memory 7 (or in addition - recording in video memory), the successive bytes of each sub-plug are sent to the interface 10 and from there to the display screens connected to the Sa outputs (Minitel screen) or 6a (monitor screen and / or screen of a television set).

 As goes without saying and as it follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have been more especially envisaged; on the contrary, it embraces all variants

Claims (7)

 1. Image display device for a telematic network for transmitting digital information, characterized in that it comprises, in its structure, in combination: an interconnection bus (1); a management and calculation unit (2) connected to this bus; a read-only memory (3), connected to the bus, containing the software for receiving, storing and / or viewing images received from the telematic network; a random access memory (8) connected to this bus; a video (7) memory connected to this bus for processing and storing the digital image information received from the bus; a network interface (9), of the peripheral with the telematic network, interface also connected to the bus in order to allow the exchange of information between the network and the management and calculation unit and occasionally the entry into the RAM of additional specific software; a video interface (10) receiving on its input (10a) digital image information from the video memory and outputting, on at least one output (5a, 6a), video signals to at least one display module; and a logic unit (14) for controlling the operations of the peripheral, connected to the bus and to the video memory.  2. Device according to claim 1, characterized in that the peripheral further comprises an autonomous electrical supply (11,13), capable of saving the information which it contains in the event of interruption of the electrical supply by the external electrical network .  3. Device according to claim 1 or 2, characterized in that the management and calculation unit (2) is a microprocessor.  4. Device according to any one of the preceding claims, characterized in that the single display module or one of the display modules, connected to an output (5a) of the video interface (10), is constituted by the screen module of a Minitel device, equipped with a video input socket (5c), the peri-computer socket module of this Minitel device is connected (4b, 4a) to the network interface (9) of the peripheral, and the Minitel keyboard module allows you to control the reception, storage and / or viewing of images on the screen module of the latter.  5. Device according to any one of the preceding claims, characterized in that it implements software which allows it to view the images contained in an image file whose pixels are digitized in ASCII code and in which each image is coded on several sub-files, all of which constitute the "file" of the complete image, each sub-file storing a matrix of pixels by rows and columns and the successive sub-files each containing digital information on all the pixels of the image, but with increasingly fine grayscale or hue details.  6. Device according to claim 5, characterized in that the gray level or the tint of the successive pixels is coded in the form of bytes whose first two bits contain information on the invariance or not of gray or tint of the pixels later.  7. Terminal constituted by the structure of a peripheral according to claim 1, 2, 3, 5 or 6, a screen module connected to said video interface (10) and a control keyboard module connected to said bus (1).