EP0178219A1 - Synthetic video images processing method for real time visualization, and with high density information, and device using such a method - Google Patents

Abstract

Method based on the evolutionary nature over time of each of the elements to determine beforehand a cutting of the stored image (5) into distinct zones, in correspondence with the distribution of the elements in the image, and to assign to each zone a rate determined periodic refresh (between one and N image display cycles) adapted to the evolution characteristics of the elements included in the zone considered, so that the integral refresh of the image is obtained every N cycles. The invention applies to high definition synthetic visualization on board aircraft.

Description

The present invention relates to a method for producing synthetic video images for real-time viewing with high information density. The invention also relates to any device using this method.

The invention is more particularly envisaged for use on board airplanes in navigation aid systems by viewing symbols on cathode screens.

There are different types of synthetic image generators of different nature and performance. Among the most efficient jumper symbol generators are intended to present the symbols according to a so-called jumper random scan. These symbol generators are fast, work in real time, have good integration and advanced software; on the other hand, the figuration is linear. The other types of generators such as commercial LSI, CAD systems, simulation systems have drawbacks for certain applications such as poor representation or a large size. Synthetic image generators on board aircraft today use the jumper scanning mode, television scanning is generally reserved for video image sensors such as cameras, FLIR, etc.

The object of the invention is to provide an ordinary image generator which, thanks to an image memory, can control displays using scans which may be different, namely the jumper scan for which the image generator is provided in direct connection, that is to say other types of scanning by means of an image memory such as the raster scanning called television or the matrix scanning.

In the case of a real-time jumper scan, the Symbol generator must redraw even if some figures are fixed or evolve slowly. The tracing is repeated at a frequency compatible with the persistence of retinal images. For a given scanning period corresponding to the duration of an image trace, the capacity of the trace is limited since for each figure or element which is variable, the computer must carry out calculations and indicate in each period the new data. from drawing to the symbol generator. Thus, as the number of figures to be traced increases, saturation is reached or else the duration of drawing of the image must be increased, this duration however not being able to be greater than that limit compatible with the concept of persistence. retinal images, approximately 25 images per second.

To obtain a graphic image according to a television scan. It is known to use an image memory and to work according to the so-called "double page" process, that is to say that a first image memory is used for writing while a second memory is scanned during reading and erased as the reading is carried out, and so on by switching the image memories at the end of each reading. This solution has a drawback in that the memory which is read for viewing is erased as and when all the elements of this memory must then be refreshed by the symbol generator.

According to the invention, a distinction is made between symbols with slow or fixed evolution which in a way constitute the "decor", symbols with faster evolution which constitute, on the contrary, what will be called "actors". We propose to place the decor in one (or more) image plan. By image plane is meant a memory assembly containing all the information for producing an image. The actors are located in one (or more) other image plane. It is necessary to modify the position of the symbols. fast-evolving ie actors, as often as possible; this modification is therefore carried out at the rate of the video, that is to say at the frame rate. On the other hand, it is not necessary to modify as often the image plane (or plans) containing the fixed or slowly evolving elements constituting the decor, the corresponding refreshment being able to be carried out over a longer time. At each video cycle of reading an image, we are thus led to modify the image plane containing the actors, while the one containing the scenery is only modified during certain cycles, or over a certain number of cycles.

• - d'un moyen générateur de symboles cavaliers ;
• - d'adapteurs spécifiques, circuits interface, etc,
• - et de mémoires d'images.

The image generator proposed is thus constituted:

• - a means for generating jumper symbols;
• - specific adapters, interface circuits, etc.,
• - and image memories.

The advantages of this synthetic image generator set are numerous. It uses an image generator, for example of the VLSI type which has high performance, allowing a high capacity for graphic descriptions at low volume and low consumption. It also uses all the basic software (assemblers, simulators, tuning for both rider and raster applications). It allows you to view raster images with all the flexibility of jumper symbol generators (rotation, circle, etc.). The same symbol generator can directly control viewing in parallel directly on screens where the tracing is done by jumper scanning and indirectly, via image memories, viewing on cathode screens or scanning is done by screened. It allows for inlay on a TV image from a sensor, with the flexibility of the current jumper symbol generators. It uses the same operational software to present in certain cases the same images on screens of different nature; the figuration normally presented on a display in jumper mode can be presented on another display in raster mode without requiring the programming of two different symbol generators. It facilitates reconfiguration in the event of a breakdown.

According to the invention, a method of preparation is proposed. synthetic video images for viewing in real time and with a high density of information, according to which the image is memorized, the method being characterized in that account is taken of the evolutionary nature over time of each of the elements to be displayed and their respective speed of evolution to determine, a cutting up of the image stored in distinct zones, in correspondence with the distribution of said elements in the image, and to assign to each zone a periodic refresh rate determined between an image viewing cycle and a maximum number N of cycles, said rate being adapted to the characteristics of evolution of the elements included in the area considered so that the complete refresh of the image is obtained every N cycles , allowing to lighten the entry in memory during each cycle by a selective refresh while preserving the visualization in real time.

• - la figure 1, un diagramme général d'un dispositif de visualisation d'images sythétiques conforme à l'invention ;
• - la figure 2, une image synthétique mémorisée sur deux plans, conformément au procédé utilisé ;
• - la figure 3, un exemple de distribution en zones de l'image avec les fréquences respectives de rafraîchissement ;
• - la figure 4, un diagramme d'un dispositif de visualisation conforme à l'invention permettant les visulisations cavalier et télévision ;
• - la figure 5, un schéma simplifié des circuits utilisés pour le rafraîchissement.
• - la figure 6, un diagramme d'un exemple de réalisation des circuits de rafraîchissement.

The features of the invention will appear in the description which follows, given by way of nonlimiting example, with the aid of the appended figures which represent:

• - Figure 1, a general diagram of a display device of synthetic images according to the invention;
• - Figure 2, a synthetic image stored on two planes, according to the method used;
• - Figure 3, an example of distribution in areas of the image with the respective refresh rates;
• - Figure 4, a diagram of a display device according to the invention allowing jumper and television visulizations;
• - Figure 5, a simplified diagram of the circuits used for cooling.
• - Figure 6, a diagram of an exemplary embodiment of the refresh circuits.

Referring to FIG. 1, the device comprises a symbol generator circuit 1 of conventional type which delivers synthetic video signals VS for drawing in real time according to a jumper scan also called random scanning. The synthetic video image is thus formed on the screen of a cathode ray tube of an associated viewing device 2, according to a known procedure. Dialog and calculation means 3 are normally provided in such a configuration for controlling the symbol generator 2 in order to produce the desired image display for operation and to make this image evolve correspondingly over time. The necessary data are transmitted to generator 1 by the link SI.

To produce, from the same VS signals, a synthetic image according to this time a television scan or a matrix scan and to display an image with high information density, there is provided a corresponding display device 4, with cathode ray tube or panel. matrix, and image storage means 5 which are interposed between this device 4 and the generator 1. This does not exclude the possible joint use of the display in jumper scanning 2.

According to the invention, the storage means 5 are arranged in a particular way to present a large drawing capacity and to meet the fixed criteria which are: an image display with a large number of symbols. This organization is based as it was said previously on the distinction which is made between the moving parts called actors which represent the evolving and therefore changing parts of the image, and the remaining parts which are fixed parts called decor and in which also includes parts that are not very mobile, called semi-fixed, which show little change over time. By noting that the data of these different parts of the image will vary correspondingly, quickly for the moving parts and slowly or not for the other parts, it follows that we can determine a cut of the image in zones and assign them respectively a refresh rate appropriate to the evolution of the elements they hold.

It should be noted that this cutting is not compulsory. rement frozen and can itself vary over time, as well as obviously the refresh rates assigned to the zones. To facilitate understanding, reference is made to FIG. 2 where we have considered the image distributed over two planes, a plane Pl which represents the decoration and a plane P2 which represents the actors. In the simple example shown, the decor is considered in the form of a landscape which is assumed to be fixed and the actors constituted by a mobile element such as a vehicle VM which moves on the road R of the decor. As the vehicle moves on this road R, the zone Zl which delimits the element VM will decrease and change more and more slowly. Consequently, this zone Z1 containing the mobile VM is to be considered of variable dimensions, as well as its refresh rate. The corresponding variation data are pre-programmed and / or calculated according to the forecast or measured evolution to allow a display adapted to reality.

It should also be considered that one can have different modes of exploitation according to which the synthetic image to be represented is different from one mode to another. This mode parameter also corresponds to other programming. A management and control circuit 6 is provided for producing the sequencing of the reading, and the addressing of the image memory, as well as the selective refresh, that is to say the writing located in this memory. The management and control circuit 6 produces these different functions; it receives from the calculation circuit 3 the operating mode information S2, it exchanges with the symbol generator 1 all the data S4 corresponding to the cycles or to the refresh zones, the link S3 to the circuit 5 represents the addressing commands and the signals S5 the display command at 4.

The image memory 5 comprises at least one memory plane for storing the elements making up the image in different zones depending on whether they are elements belonging to the decor or to the actors and according to their speed of evolution. Each zone is assigned to a refresh rate determined according to this last parameter. The refresh rates can thus vary between 1 and N image cycles, the areas forming the actor part being refreshed at the fastest rate, that of the image, and the areas of the decor part at slower rates ranging from 2 to N cycles as appropriate.

However, to meet the criteria of large drawing capacity and to visualize a high number of symbols, the memory 5 is preferably organized with several memory planes, at least one memory plane to contain an image plane limited to the decor and at least one memory plane to store an image map corresponding to the actors. Each image plane is coded on one bit, or on several bits if there are several memory planes per image plane. The image plane is divided into zones whose dimensions can change over time and which are each assigned a refresh rate which can also change over time.

In FIG. 3, a cut into zones of the image is shown, where for example fourteen different zones have been considered for the operating period considered and eight distinct refresh rates. The IF frequency corresponds to a refresh at the frame rate, the F5 frequency to a refresh every five frames, etc. The different frequencies are indicated FI to F8. The IF frequency zones have, for example, been highlighted by dotted lines to show the parts of the image, refreshed at this rate. It is understood that the deletion of a zone is followed by its rewriting on pain of having a hole in the configuration. In the example of FIG. 3, the zones coded on three bits have been considered, which allows eight refresh codes. For a coding on four bits we would have sixteen refresh codes. The areas are delimited by rectangular polygons.

This produces a selective refresh, the circuits used allow an image plane of the decor not to completely refresh the image each time it is read. Zones can be defined by a programmable memory 61 called PROM, or by a random access memory, managed by a microprocessor 62 and having a resolution of a certain number of pixels, for example thirty two pixels maximum. We can select, via a bus, a certain number of refresh modes, for example sixteen modes corresponding to sixteen formats for splitting into refresh zones.

Figure 4 shows in more detail the structure of Figure 1, the device further comprising: an interface circuit 10 which receives from the symbol generator the address data in X and in Y and the color video data of the synthetic video; an image bus; a digital-analog converter 11 and a transcoding memory 12 which reproduces from the image memory 5 the RGB video intended for color display. Depending on this configuration, two types of image can be produced simultaneously or not, one in jumper scanning on indicator 2, and the other in raster scanning or television on indicator 4. For each presentation mode, endeavors to use the specific possibilities of this mode and the whole allows using the same software and the same symbol generator 1 to take advantage of the specific advantages of each mode of representation.

As an example, we can consider that the full refresh of the displayed image, that is to say of the set of actors and set, will be carried out after eight image cycles, that is to say - say eight frame periods. During each of these eight video cycles, the entire image is read, that is to say simultaneously from the different "decor" and "actor" image planes to produce the corresponding visualization. The areas of the actor image plane are all erased at the frame rate so as to completely refresh this plane at each image cycle. On the other hand, the areas of the decor image plane are erased and refreshed selectively at rates varying between 2 and 8 image cycles. We thus modify at each cycle all the elements of the actors' image plane while in the image plane of the set, we modify a limited number of elements corresponding to one or more zones. It is understood that during each of these cycles, after reading, only the memory elements which will be modified in the following cycle are erased, namely, the entire image plane of the actors and part of the image plane of the decor. The division of each image plane of the memory into refresh zones makes it possible to isolate the elements of this plane from one another. Each of these planes is divided into elementary surfaces defining the cutting resolution. Each cooling zone comprises one or more elementary non-contiguous surfaces. The same refresh zone cannot have several elements having different refresh cycles.

FIG. 5 diagrammatically represents means included in the management and control assembly 6 and used to refresh the image memory 5. These refresh means comprise a refresh memory 20 and a video cycle counter 21. The counter delivers output the cycle number information. The refresh memory receives, moreover, the indication S2 of the refresh program type and the addresses AX for reading in X and those AY for reading in Y, to which an elementary surface corresponds each time. The refresh memory 20 provides a corresponding erase order S3 to the image memory. The refresh memory 20 contains for each elementary surface the refresh cycle number (s) of the zone concerned. This memory is read in synchronism with the image memory and gives the order to erase the image memory. The refresh memory can be chosen so as to be able to reproduce the zone configurations by program, for example at mode change. The symbol generator program works on multiple cycles of the video and is able to manage the different symbols over time.

FIG. 6 shows in more detail an exemplary embodiment of the above-mentioned refresh circuits. The memory of refresh 20 consists of elements 20A and 20B. In the first memory 20A are stored the data defining the configuration of the zones. This first memory 20A receives by a bus B1 the coded information defining the zone configuration for the selected operating mode, or for the current operating phase (case of operating mode with configuration of zones evolving over time. ). The read addresses AX and AY for reading are received by the link B1. The output B3 of the first memory 20A gives the coded information of the zones to be read at the instant considered. This information is transmitted to the second memory 20B which receives: from the counter 21 the cycle number information; from a bidirectional bus B4, the zone read, erase and refresh control information; and from a bus B5 the coded information of the image plane to be refreshed. The second memory 20B delivers the signals S3 to the image memory 5. The signals BI, B2, B4, B5 can be produced by the microprocessor 62 on the basis of the information S2 received from the annex dialogue and calculation unit 3 and from the symbol generator I. In addition, this microprocessor can deliver frame synchronization information ST to the image cycle counter 21. The counter 21 can be put out of service by an inhibition command SCT, called the tristate command, and in this case the symbol generator 1 can provide the refresh commands.

It is understood that the programming provided in the command and management assembly 6 can be done to define the cutting of the zones, both from the point of view of the position of the zones and of an evolving form thereof. , and that the duration N of image cycles necessary for full refreshment is determined so as to preserve an image display reproducing viewing conditions in real time, or very substantially.

Claims (10)

1. Method for developing synthetic video images with a view to real-time viewing and with a high density of information, according to which the image is memorized, the method being characterized in that the evolutionary nature over time of each of the elements to be displayed and their respective speed of evolution to determine a division of the image stored in distinct zones, in correspondence with the distribution of said elements in the image, and to assign to each zone a determined periodic refresh rate between an image viewing cycle and a maximum number N of cycles, said rate being adapted to the characteristics of evolution of the elements included in the area considered so that the full refresh of the image is obtained every N cycles, allowing to lighten the memory entry during each cycle by a selective refresh while preserving the visualization in real time. 2. Method according to claim 1, characterized in that the image cutting into zones is carried out on a single memory plane comprising all the elements of the image. 3. Method according to claim 1, characterized in that the image cutting into zones is carried out on at least two stored image planes (Pl, P2), a first image plane (Pl) comprising the fixed elements and slowly evolving and a second image plane (P2) comprising the remaining elements (R) of the image, with faster evolution. 4. Method according to any one of claims 1 to 3, characterized in that the dimensions of the zones (Zl, Z2) and their respective refresh frequency (Fl, F2, ...) also vary over time as a function of the evolution of the elements. 5. Method according to claim 3 or 4, characterized in that said second image plane is read and refreshed at the frame rate (F1) and that each region of the first image plane is also read at the frame rate but is only refreshed at a higher frame rate, multiple of that of the frame (F2 to FN), the refresh rates ( F2 to FN) of said first plane varying from two cycles to N cycles and being allocated respectively to the zones according to their respective evolution criterion, the whole of said first plane being refreshed after N cycles. 6. Method according to any one of claims 1 to 5, characterized in that said cutting is predetermined by the selected operating mode and that it is modified when switching to another operating mode, to respond to a new distribution of elements to be displayed and consecutively corresponding image areas. 7. Method according to any one of claims 1 to 6, characterized in that the cutting into zones is programmed to define both the position and the shape of the zones and that the duration N of cycles of the integral refresh of the image is determined to preserve a visualization thereof in conditions corresponding to a visualization in real time. 8. Device comprising a symbol generator (1) delivering synthetic video signals (VS) of the image to be displayed, dialogue and calculation means (3) for controlling the generator, a screened display device (4) and image storage means (5) intermediate between the generator and the display device, said device using the method according to any one of claims 1 to 7 and being characterized in that the intermediate storage means (5) are organized according to two image planes each bringing together one or more cards, a first image plane for storing the fixed elements and those with slow evolution, and a second plane for the fast elements. 9. Device according to claim 8, characterized in that it comprises a command and management circuit (6) which receives information (S2) of the selected operating mode from the dialogue and calculation means (3), and which develops the addressing signals, reading and refresh (S3) of the intermediate memory means. 10. Device according to claim 8 or 9, characterized in that it further comprises a jumper display device (2) supplied directly by the symbol generator (1).

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