VWGoA - Ex. 1036
`Case No. IPR2016-00156
`Volkswagen Group of America, Inc. - Petitioner
`West View Research, LLC - Patent Owner
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`U.S. Patent
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`Nov. 2, 1993
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`Sheet 1 of 2
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`5,258,837
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`FIG 1A
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`U.S. Patent
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`Nov. 2, 1993
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`Sheet 2 of 2
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`5,258,837
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`NOE
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`MULTIPLE SECURITY VIDEO DISPLAY
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`5,258,837
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`This is a continuation of copening application Ser.
`No. 07/730,111 filed on Jul. 15, 1991, now abandoned.
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`BACKGROUND OF THE INVENTION
`
`invention relates to multiple video
`The present
`monitoring—that is, to the simultaneous monitoring of
`pictures received from a plurality of video picture
`sources—and is particularly concerned with such moni-
`toring for security and similar surveillance purposes.
`The use of video cameras and their associated video
`monitoring units has become an indispensable compo-
`nent of modern security and protection services. The
`number of cameras that might be employed at an institu-
`tion has steadily increased with time as the expense of
`surveillance cameras has decreased. In some locations,
`such as gambling casinos, it is not uncommon for hun-
`dreds of cameras and their associated monitors to be in
`use.
`
`In any such system, a compromise has to be struck
`between cost and effectiveness. For maximum effective-
`ness, the picture from each separate camera would be
`watched by a separate security officer. However, that
`would normally involve grossly excessive wage costs,
`particularly in camera-rich and monitor-intensive set-
`tings. Each operator (security officer) is therefore as-
`signed a plurality of pictures to watch. Such surveil-
`lance imposes a considerable strain on the operator, in
`that he or she must continually scan a number of indi-
`vidual television monitors equivalent to the number of
`video sources.
`
`It should be noted that limitations may also be felt as
`a result of the physical size of the video monitors. Even
`if no expense were spared in the numbers of operators
`assigned to view monitors, it rapidly becomes prohibi-
`tive to install and maintain a large number of expensive
`and physically large monitor units in location where
`operating space is of a high value (such as a gambling
`casino).
`Staying with the example of a gambling casino, the
`design of the details of such a system involves a choice
`between a number of further and partially conflicting
`requirements. With the operator being assigned to ob-
`serve a set of monitors, the pictures should be large
`enough to allow the operator a good view of the details
`of each picture. This is normally achieved by placing
`the operator within easy view of several large monitors.
`This achieves the immediate object, but naturally re-
`sults in the operator being left with one or more of the
`monitors outside their immediate gaze if their attention
`should be drawn to an activity on a single monitor.
`One apparent solution is to concentrate a number of
`smaller video monitors closer to the operator. The re-
`sult is an increase of pictures in the operator’s immedi-
`ate eye scan range, but it is inherent in the nature of
`small video monitors that it becomes more difficult to
`carefully observe details, such as an individual’s face or
`subtle actions.
`The fundamental difficulty is simply the limitation on
`the area that might be within the comfortable gaze of a
`single operator. If there are multiple pictures to be mon-
`itored, the operator may fail in their assignment because
`of having to turn their head in the process of trying to
`observe several large monitors, or simply fail to notice
`an action if it occurs on one of several small monitors
`that are located within their immediate gaze.
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`A different approach to the problem is to utilize a
`single monitor on which a substantial number of images
`from different sources (cameras) are displayed. A typi-
`cal number of images is 16, in a 4x4 pattern or array.
`This can be achieved by performing an image reduction
`process on each source picture, to turn it into an image
`of reduced size. Each so reduced image is written into a
`corresponding area in a buffer memory which stores the
`total of 16 images, and the buffer memory is scanned as
`a whole to produce the resulting compound picture of
`16 images.
`However, although the hardware involved in this
`approach differs fundamentally from the plurality of
`monitors discussed above, there are considerable func-
`tional similarities. Both approaches generate an array of
`identical pictures or images of equal area.
`One major difference is that with a plurality of sepa-
`rate monitors, the pictures are separated by the physical
`borders of the various monitor screens, while with a
`single monitor, the images are generally continuous.
`The other major difference concerns the size of the
`system. With a single monitor, the images on it will
`generally be relatively small even though the monitor
`will generally be chosen to be relatively large, whereas
`with a plurality of separate monitors, the pictures will
`generally be relatively large and placed at a consider-
`able distance from the observer even though the indi-
`vidual monitors may be relatively small.
`Such systems therefore generally involve the striking
`of a compromise between having the system as a whole
`small enough for all the pictures or images to be readily
`observable by the observer without inconvenience, and
`having the individual pictures or images large enough
`for small details to be readily observable.
`SUMMARY OF THE INVENTION
`
`The crux of the present invention is the generation, in
`multiple video monitoring apparatus, of a plurality of
`complete images of different sizes as a single composite
`picture on a single monitor, together with selection
`means for selecting any desired one of the small images
`for display as a large image. In the preferred arrange-
`ment, the monitor screen is notionally divided into 1
`large zone for a large image, substantially a linear half of
`the screen size, in the centre of the screen, and 12 small
`zones for 12 small images, each substantially a linear
`quarter of the screen size, arranged around the border
`of the large zone.
`The monitor and the zones into which it is divided
`will normally all have the same aspect ratio, and this
`imposes considerable restraints on the sizes and arrange-
`ments of the zones on the monitor. As just noted, the
`preferred arrangement divides the monitor screen into
`12 small zones, each making up substantially 1/ 16th of
`the screen, and 1 large zone, taking up substantially I of
`the screen (i.e. 4 times the area of each small zone); and
`the large zone is preferably also centred in the screen, so
`that there are 2 small zones contiguous with each of its
`sides, and 4 more small zones in the comers of the
`screen. More generally, the screen can be regarded as
`notionally divided into a square of n><n congruent ar-
`eas, with one or more mxm squares of these notional
`areas being merged into each other to form larger
`squares. The merged blocks are used for large zones,
`and the remaining areas for the small zones.
`Thus the simplest case is the 3X3 one, giving L a
`division into 5 small zones, each substantially a linear
`third of the monitor screen, and a single large zone, a
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`linear two-thirds of the screen. This, however, has the
`disadvantages that the large zone is displayed from the
`centre of the screen, and the number of small zones is
`limited to 5.
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`The next simplest case is the 4X4 one, giving the
`preferred arrangement of a central large zone substan-
`tially a linear half of the screen and surrounded by 12
`small zones each substantially a linear quarter of the
`screen. However, this case permits other arrangements
`as well. It will usually be preferable to have the large
`zone located centrally, but it is possible to locate it at an
`edge or a comer of the screen. This would pennit a
`second large zone to be accommodated on the screen
`(with the number of small zones then being reduced to
`8).
`The next case up is the 5X5 one, which allows a
`considerable number of possible arrangements, such as a
`central large zone of substantially three-fifths linear size
`surrounded by 16 small zones, or 4 large zones each of
`substantially two-fifths linear size separated by 9 small
`zones arranged in a cross. The same principles obvi-
`ously apply further up the scale, though if the number
`of zones becomes too large, a single operator cannot be
`expected to scan them all effectively.
`Obviously, not all the small zones need be fed with
`live camera video. For example, the preferred screen
`arrangement might be fed from only 10 cameras, leav-
`ing 2 zones blank. Such blank zones are preferably
`shown in neutral form e.g. as dark grey If there are such
`blank zones, it may be possible to adjust the positions of
`the zones with real images. For example, with 2 out of
`13 zones blank, the large central zone may have 2 small
`real zones on each side, and 3 small real zones arranged
`centrally along its top and bottom. (In effect, this in-
`volves splitting the 2 blank zones into halves, and locat-
`ing the 4 halves one at each end of each of the rows of
`3 small real zones.)
`The terms “television” and “monitor” have been used
`indifferently so far. Although there is no fundamental
`distinction, in practice these two terms are generally
`taken as describing slightly different kinds of system.
`A television system is typified by the public broadcast
`systems, while a monitor system is often of the type
`used for data display in computer systems. The relevant
`distinction for present purposes is as follows. In a televi-
`sion system, the picture size is usually slightly larger
`than the screen, so that the visible picture extends right
`up to the frame or casing round the display tube and the
`edges of the picture are lost. In a monitor system, the
`picture size is somewhat smaller than the screen, so that
`the whole of the picture is visible and there is a blank
`border visible round it on the screen, and the definition
`of the picture is often better than for a television system.
`The present system is preferably implemented using a
`monitor system. This gives good picture quality, and
`ensures that the whole of every zone is fully visible.
`Straightforward implementation of the present system
`using a television system for the purposes of security
`and similar surveillance purposes will not generally be
`acceptable, because of the masking of picture area
`round the edges of the screen.
`This problem can be overcome if necessary by modi-
`fying the system so that the zones are slightly smaller
`than those discussed above. Thus with the “l +12”
`arrangement, for example, a (linear) reduction ratio of
`say 0.46 rather than 0.50 for the central zone and of 0.23
`rather than 0.25 for the 12 small zones may be sufficient
`to ensure that the whole of the composite picture is
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`visible on a conventional domestic consumer television
`screen.
`It has been assumed above that the zones are all con-
`tiguous. It may however be preferable to separate them
`slightly,
`introducing narrow borders between them.
`This again requires the reduction ratios to be changed
`slightly, so that the whole of the composite picture can
`be accommodated on the screen. The dividing border
`may conveniently be set to dark grey.
`It may be desirable for the images to be identified.
`One way of achieving this is for each camera to have
`associated with it an identification unit which inserts an
`identification signal (e. g. an alphanumeric message) into
`its picture. This results in the message forming an indi-
`visible part of the image, so that the message will be
`enlarged together with the rest of the image if that
`image is selected for the large zone.
`Another way of achieving this is for the identification
`signals to be generated in association with the genera-
`tion of the composite picture. This permits the message
`to remain the same size regardless of the size of the
`associated images. If the composite picture has neutral
`borders between the zones, then the messages can be
`displayed in those borders.
`In a security system, the system will comprise the
`video monitoring apparatus and will also include a num-
`ber of video cameras (directed, for example, at regions
`occupied by patrons and employees of a casino) and
`providing the pictures to be displayed on -the monitor.
`In general, something suspicious might occur on any of
`the images, and it will be necessary to allow the security
`officer to take a closer look at the suspicious picture
`area. The present system therefore includes selection
`means for selecting any desired one of the small images
`for display in the large image area.
`The selection means may include a so-called “touch
`screen" control device attached directly over the video
`display screen. Such a device allows the operator to
`select any one of the small images to be enlarged within
`the large image area at will. This allows the operator to
`literally point his or her finger or other object at a sus-
`pect individual and then see the small image duplicated
`for detailed examination as the central large image.
`The usual mode of operation of the system will gener-
`ally be a simple select mode, in which there are 12 (at
`most) video sources each displayed as a corresponding
`small image, with the selection means operating to per-
`mit the duplication of the selected image in the large
`zone. However, an alternative mode of operation is the
`swap or shuffle mode, in which the selection of any of
`the small images for enlargement results in that small
`image being swapped with the picture currently shown
`in the large zone The swap mode allows 13 picture
`sources to be monitored, but has the disadvantage that
`there is no permanent association between the picture
`sources and the zones (image positions) on the screen.
`In some forms of security system, such as a casino
`security and monitoring system, the system will also
`include a video image storage unit (which could for
`example include a “rogues’ gallery" of still images of
`individuals who are suspected by the casino to be un-
`trustworthy). The video stills storage unit might be
`accessed by the operator and various faces could be
`called up from storage and displayed in one of the video
`zones so that an individual under observation may be
`matched against a likeness within the stills storage file.
`It was noted above that in the 4X4 case and above,
`there is more than one possible arrangement for divid-
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`ing the screen between large and small zones. It is possi-
`ble for the apparatus to be switchable (under operator
`control) between two (or more) different he situation
`just mentioned, where there is a “rogues’ gallery” of
`still pictures. The normal screen arrangement will be 1
`large zone surrounded by 12 small zones, but when a
`still picture is to be compared with one of the other
`pictures, the two pictures (the still and the one which it
`is being compared with) could both be displayed as
`large images, side by side. (This would mean, of course,
`that if there are more than 8 small images, then some of
`them would be temporarily lost.)
`Textual information for display may also be included
`in the system, either in the video stills storage unit or in
`a separate text generator unit, which can preferably be
`accessed as an alternative to the video stills storage unit.
`In some gambling establishments, there may be vari-
`ous different rooms with different games ani/or of dif-
`ferent sizes, and different rooms may be in use at differ-
`ent times. Obviously the total number of surveillance
`cameras can be more than 12, as long as not more than
`12 are operative at any one time (or 13 if the system is
`operating in swap mode). The particular selection of
`cameras operating can of course be changed under
`operator control at any time. If it is attempted to moni-
`tor substantially more than 12 locations by fairly rapid
`switching of cameras, this will of course be liable to
`cause operator confusion, though this will be minimized
`if the pictures are identified, in any of the ways dis-
`cussed above.
`If the establishment consists of two separate buildings
`or groups of buildings, it may be convenient to provide
`two control rooms, one in each building, with a single
`surveillance system having two monitors, one in each
`control room, both showing the same composite image.
`For greater security, each control room can have a
`camera, so that the two control rooms form 2 of the 12
`images on the monitor. Each control room can thus
`monitor the other. Each control room would be pro-
`vided with a selector device for selecting one of the 12
`small images for display as the large central image. At
`off-peak times, when one or other of the two buildings
`was closed, the corresponding control room would also
`be closed down.
`It will be realized that the present system bears a
`, superficial resemblance to some known systems, for
`teleconferencing and the like, using PIP (picture in
`picture)
`techniques. Examples of such systems are
`found in US. Pat. Nos. 4,965,819 (Kannes) and
`4,650,929 (Boerger et al); the PIP process itself is de-
`scribed in Japanese Patent No. 62-108692. At first sight,
`these approximate in general appearance to the present
`system. The video conferencing system of Kannes in-
`cludes a video display that is illustrated with either five
`or six active video images seen on a single screen. Like-
`wise, Boerger et al teaches that one, or elements of at
`least twelve video images can be depicted on a single
`screen.
`
`However, the technology employed by these known
`systems leaves them with severe limitations that makes
`them fundamentally unsuitable for critical monitoring
`and security applications. In both of these systems, one
`of the incoming pictures is deemed to be more impor-
`tant than the others. This major picture is fed directly to
`the monitor screen, to be displayed as a full-sized pic-
`ture occupying the whole of the screen, and the remain-
`ing pictures are inserted inside the large picture by PIP
`techniques.
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`The effect of this is that those areas of the large image
`where the small images have been inserted are effec-
`tively lost from view. If several small images are so
`inserted, the total area of the large image lost from view
`in this manner is substantial.
`In the present context of security and surveillance,
`the large image will normally have been deliberately
`selected as the most important one. The loss or effective
`deletion of areas from the large image which would
`result from the adoption of PIP techniques, such as
`those of Kannes or Boerger et al, is unacceptable. In the
`context of teleconferencing and other uses envisaged by
`Kannes and Boerger et al, the small images are located
`in regions of the large image which are less likely to be
`important, and if something in those regions should be
`important, the viewer could ask for the view to be
`changed to bring the obscured Part of the image to a
`different part of the screen. In the context of security
`and surveillance, however, that is clearly not an accept-
`able option.
`Further, in the context of security and surveillance
`the number of images which need to be monitored is
`likely to be larger than the number of images contem-
`plated by, for example, Kannes. This would increase the
`fraction of the main image which is lost. This loss of
`picture content can be reduced by making the small
`images smaller, but that results in a loss of definition and
`quality of the small images.
`It might be possible to arrange for the locations of the
`small images to be made variable, so that the operator
`could move them away from areas of particular interest
`in the main image, but that would greatly increase the
`complexity of the system. Further,
`it would greatly
`increase the chances of the operator becoming con-
`fused, since it would impose additional unnecessary
`“housekeeping” tasks on the operator in addition to
`their primary duty of observing the selected image
`closely for actions which are intended by their commit-
`ters to be clandestine.
`In contrast to these PIP systems, the present system
`involves the display of the large image with no loss or
`any part of it (though with a certain reduction in its
`overall size which is easily compensated for by increas-
`ing the size of the viewing monitor).
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Further features of the invention will become appar-
`ent from the following description of systems embody-
`ing the invention, given by way of example and with
`reference to the drawings, in which:
`FIG. 1 shows the division of the monitor screen into
`zones;
`FIG. 1A shows a modification of the FIG. 1 division;
`and
`FIG. 2 is a block diagram of a security system.
`DESCRIPTION OF THE EMBODIMENTS
`
`FIG. 1 shows the monitor screen display, which has
`a conventional aspect ratio of 4:3. This is divided into 12
`small zones Z-1 to Z-12 and a large zone Z-13, which all
`have the same aspect ratio as the screen display and
`which together fill the display area. The small zones are
`each a quarter of the linear size of the display area, and
`surround the large zone, which is half the linear size of
`the display area.
`FIG. 1A shows a modified form of the FIG. 1 ar-
`rangement,
`in which zones Z-1 to Z-12 are slightly
`smaller than a quarter of the display area and zone Z-13
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`then all the zones will be written into broadly in paral-
`lel.
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`It will be realized that instead of the single read/write
`buffer memory 24, the effects unit 20 could contain a set
`of 12 separate memories, one for each camera. Each
`would have its locations written into in strict sequence
`line by line down the buffer and point by point along
`each line, independently of the other memories; but in
`this arrangement, the reading from the memories would
`be more complicated.
`The read-out would start by proceeding cyclically
`through memories 1 to 4, reading along every 4th row
`in those memories and reading every 4th location along
`the selected rows. When reading from those memories
`is finished, the read-out will proceed to memories 12, k,
`and 5, in cyclic order, reading along every 4th row in
`memories 12 and 5 and reading every 4th location along
`the selected rows in those memories and along every
`2nd row in memory k and reading every 2nd location
`along the selected rows in that memory. When reading
`from memories 12 and 5 is finished, memory k will have
`been only half read. The read-out will proceed to mem-
`ories 11, k, and 7, again in cyclic order. Reading will
`proceed along every 4th row in memories 11 and 6,
`reading every 4th location along the selected rows in
`those memories, and will continue along every 2nd row
`in memory k, reading every 2nd location along the
`selected rows in that memory. When reading from
`those memories is finished, the read-out will proceed to
`memories 10, 9, 8 and 7 in cyclic order, reading along
`every 4th row in those memories and reading every 4th
`location in those memories.
`In this arrangement, memory k would be one of the
`memories 1 to 12, selected by the selector 25. Thus
`whichever one of the memories had been selected
`would undergo double reading, in two different modes.
`Of course, a 13th memory could be used for memory
`k, so that each memory would only be read once. The
`output of the appropriate camera would have to be
`directed to the 13th memory as well as its own memory
`If the composite picture is of the form shown in FIG.
`1A, then identification signals can alternatively be gen-
`erated in the marginal areas ZMID as shown. If this is
`done, it is convenient for these signals to be generated in
`the effects module 20 rather than at the cameras.
`The system control unit 26 is preferably located adja-
`cent to the effects unit 20 and switching unit SW1,
`while the selector 25 and keyboard 30 are located adja-
`cent to the monitor 21.
`In addition to the selector device 25, there is a key-
`board 30 controlled by the operator and connected to
`the system control unit 26. A video stills image store 31
`has its output connected, via a stills monitor 32, to a
`further input to the switching unit SW1. By means of
`the keyboard, a desired still image from the stills unit 31
`may be selected and the output from this unit selected
`by means of the switching unit SW1.
`The stills unit 31 also feeds a hard copy device 34 via
`a hard copy monitor 33. By means of the keyboard 30,
`a hard copy of the selected still may be printed on the
`hard copy device, e. g. for later study or as a permanent
`record.
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`is slightly less than half the size of the display area This
`leaves narrow marginal areas ZM between the zones.
`FIG. 2 shows a simple form of the system. 12 cameras
`C1 to C12 are directed at locations of interest, and feed
`12 input channels of an effects module 20, which in turn 5
`feeds the monitor 21 (the screen of which is shown in
`FIG. 1). A set of 12 video source generators 22 is in-
`cluded in the 12 channels; each of these generators can
`be set to insert an identification signal (such as a textual
`message) in the video output from the associated cam-
`era This results in the identification signals appearing in
`the images to which they relate.
`The effects module 20 comprises a video compression
`unit 23 and a read/write buffer 24. Unit 23 comprises 13
`sections, corresponding to the 13 input channels to the
`effects unit. The first 12 sections of unit 23 are identical,
`and each compresses the incoming signal by a ratio of
`16:1 (corresponding to the 4:] linear size reduction of
`the small image zones). The final section compresses the
`incoming signal by a ratio of 4:] (corresponding to the
`2:] linear size reduction of the large image zone).
`(It should be noted that this compression involves
`condensing each individual picture down by the appro-
`priate amount. This is completely different from what is
`sometimes termed bandwidth compression, which in-
`volves such things as comparing successive pictures and
`transmitting information about the differences between
`those pictures.)
`The read/write buffer 24 is divided into 13 zones, 12
`small and 1 large, corresponding to the 12 small image
`zones and 1 large image zone of the monitor screen. The
`outputs of the sections of unit 23 are fed to correspond-
`ing ones of the read/write buffer as indicated.
`Each zone of the read/write buffer 24 is thus kept
`filled with the current image received on the corre-
`sponding input channel of the effects buffer, while the
`whole contents of the read/write buffer are fed as a
`composite signal to the monitor 21, which thus displays
`the 12 small images and 1 large image in the arrange-
`ment shown in FIG. 1.
`
`As so far described, the 12 small image zones display
`the pictures received from the 12 cameras C1 to C12.
`The outputs from the cameras C1 to C12 are also fed to
`a video bridging switcher SW1, shown as a multiplexer,
`which feeds the 13th input channel of the effects mod-
`ule. A selector device 25, controlled by the operator,
`has 12 switch areas arranged in a pattern corresponding
`to the 12 small image zones of the monitor 21. The
`selector 25 feeds a system control unit 26 which-in turn
`controls the switching unit SW1 to select the camera
`output corresponding to the selected small image zone.
`That camera output is therefore selected by the switch-
`ing unit, and so passed to the 13th channel to the effects
`module 20 and there processed and so displayed in the
`central, large image zone Z-13 of the monitor. (It also
`remains simultaneously displayed in its small
`image
`zone.)
`In the apparatus just described, the effects unit 20 has
`been described as including a single read/ write buffer
`24, with each location of this buffer corresponding to a
`pixel in the composite image on the monitor 21. These
`locations are read out in strict sequence line by line
`down the buffer and point by point along each line. The
`writing into these locations is more complicated. Essen-
`tially, each of the zones (the 12 small zones and the 1
`large zone) is written into (by the corresponding section
`of the compression unit 23) independently of the other
`zones. If the 12 cameras are operated in synchronism,
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`More elaborate switching means may be provided
`whereby the output from the stills unit 31 may instead
`be displayed in that one of the small image zones the
`contents of which are currently being shown in the
`large image zone. Such switching may comprise a set of
`12 relays, one for each of the camera channels, each
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`relay having one input fed from the corresponding cam-
`era and the other input fed from the stills unit, together
`with suitable control means for operating the relay
`corresponding to the channel selected for display in the
`large image zone.
`If there are fewer than 12 cameras, of course, then
`one of the small image zones can be permanently dedi-
`cated to such purposes as stills and text display.
`The effects module 20 is also coupled to a video re-
`corder 31 via a date and time stamp unit 30. Unit 30 may
`conveniently be of the type which inserts the date and
`time information into the vertical interval portion of the
`video signal (or some other portion of the video signal
`which is not associated with visible picture informa-
`tion), so that the date and time information does not
`obscure any part of the visible image (i.e. the 12 small
`image zones and 1 large image zone). This enables a
`permanent record to be made of the pictures being
`monitored.
`The video recorder may either be permanently run-
`ning or operated under control of the operator when an
`event of interest occurs.
`
`The output of the video recorder is passed, via a
`monitor 42, to the stills unit 31. This permits an image
`recorded by the system to be copied into the stills unit
`for future reference. Similarly, tapes carrying images
`recorded by other systems can be inserted into the video
`recorder and so copied into the stills unit.
`The hard copy device 34 may be fed from the video
`recorder 41, as well as or instead of from the stills unit
`31.
`
`t M
`
`10
`3. Apparatus according to claim 2 wherein n = 3, with
`a single block of 2 X 2 areas being merged to form a zone
`of larger size.
`4. Apparatus according to claim 2 wherein n=4, with
`a single block of 2 X 2 areas being merged to form a zone
`of larger size located centrally on the monitor screen.
`5. Apparatus according to claim 2 wherein n=4, with
`two adjacent blocks of 2 X 2 areas being merged to form
`two zones of larger size located centrally side by side on
`the monitor screen.
`-
`6. Apparatus according to claim 2 wherein n=4, and
`including image processing means operable in two
`modes in one of which a single block of 2X2 areas is
`merged to form a zone of larger size located centrally
`on the monitor screen and in the other of which two
`adjacent blocks of 2X2 areas are merged to form two
`zones of larger size located centrally side by side on the
`monitor screen.
`7. Apparatus according to claim 1, wherein the num-
`ber of cameras is less than the number of small zones,
`and at least one of the small zones not displaying a
`camera output is split into two half-zones located sym-
`metrically on opposite sides of the monitor screen.
`8. Apparatus according to claim 2 wherein the con-
`gruent areas are slightly smaller linearly than one n-th
`of the monitor screen.
`9. Apparatus according to claim 8 wherein the zones
`are slightly separated from each other.
`10. Apparatus according to claim 6, wherein the
`image processing means including means for generating
`a plurality of identification messages, one for each zone.
`11. Apparatus according to claim 10 wherein the
`image processing means generates the identification
`messages outside each zone.
`12. Apparatus according to claim 1 wherein the selec-
`tion switching means include a “touch screen” control
`device attached directly over the monitor screen.
`13. Apparatus according to claim 1 wherein k=l and
`wherein the image selected by the selection switching
`means as a large image remains displayed as a small
`image.
`14. Apparatus according to claim 1 wherein, on the
`selection of an image in one of the first n zones for
`display as a larger image in one of the last k zones, the ’
`larger image which it displaces is moved to that one of
`the first n zones.
`15. Apparatus according to claim 1 including a video
`image storage unit the output from which is treated as
`the output of a camera.
`16. Multiple video monitoring apparatus, comprising:
`a plurality n (n being an integer greater than 1) of
`video cameras producing respective camera sig-
`nals;
`selection switching means for selecting k (k being a
`positive integer less than n) of the camera signals;
`a picture memory;
`a plurality n+k of image compression circuits, n first
`image compression circuits of the image compres-
`sion circuits being directly co