GB2029665A - Electronic still picture storage system - Google Patents

Abstract

The system includes a storage medium such as a video tape recorder 12 on which picture information derived from and representing the same still picture is stored several times so that the tape eventually contains a number of still pictures each stored several times. On read out of a selected picture the information is received by a processor 13 which integrates the information from each of the repeatedly stored representations of this picture to provide noise reduced information. By integrating the information from the repeatedly stored pictures degradation due to shortcomings in the quality of the storage medium is removed. The still picture may have been obtained from a moving picture captured in a video store. The system may include arrangements for transmitting the picture information to a remote location. <IMAGE>

Description

SPECIFICATION Electronic still store There is a general requirement in the broadcasting industry for the storage of still pictures which are later to be used in the broadcast of a T.V. programme. The pictures are normally stored in the form of 2" transparencies on a photographic format and are transmitted by use of a flying spot scanner system.

This invention is generally concerned with a system of electronic still storage to replace the photographic method and capable of providing a compact, reliable electronic system for storing a large number of slides, such as a central library would require without degradation of the retrieved pictures.

Afurther aspect of the invention is concerned with a method of transmitting the contents of the stored pictures over telephone links to a remote point for assemblage in sequence into a smaller store, which may be accessed during the time the programme is transmitted.

Electronic still stores which are already known make use of the photographic input as the basic source of material. An electronic scanner converts the still photograph into a standard television format which is then subsequently digitized and stored in digital format on a disc. Access to the disc at some time in the future enables the picture information to be reconstructed and transmitted as part of the television programme.

The disadvantage of the known system is the high cost of storage and generally the very substantial physical size of the equipment required to store a large number of pictures.

According to the invention there is provided a still picture storage system including: storage means for sorting a plurality of picture information blocks, each block derived from and representing one and the same still picture; and picture integration processing means for integrating the information contained in the blocks to provide noise reduced picture information at an output thereof.

Further according to the invention there is provided a method of storing still pictures on a storage medium comprising storing a plurality of blocks of picture information, each block being derived from and representing one and the same still picture and integrating the information contained in these blocks when retrieved from the storage medium to provide noise reduced picture information.

In the present invention, the basic storage system may be a standard analogue or digital video tape recorder (VTR) of the type commonly found in any broadcast studio. The only requirement of such a VTR is that is shall be able to be controlled by digital signals which come from a computer, for example.

Many existing designs of VTR include this facility, which is a requirement of editing purposes. A further requirement is that it shall be possible to identify each frame position along the tape and that access to that frame may be achieved under digital control.

A preferred video tape recorder is a digital VTR of the type just becoming available on an experimental basis. In these designs, all the standard features of analogue VTRs are retained, but the track spacing on tape is modified to allow high packing density digital data to be accommodated sufficient to record television pictures without any significant loss in quality.

An experimental design using a BCN recorder has recently been described by the Independent Broadcasting Authority and other experimental designs are known to exist.

As just stated, either analogue or digital tape recorders may be used, and by using a standard VTR machine, which requires no adaption to record television signals, the system can be more simply and less expensively constructed. The known disadvantages of using tape particularly analog tape as a recording medium for long-term storage are associated with the damage that can occur to the tape and the the signal to noise ratio which degrades the analogue tape recorder performance. In the system to be described, a noise reduction system of integration is used to effectively eliminate these disadvantages.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows an embodiment incorporating the storage system of the present invention.

Figure 2 shows an alternative arrangement which allows a moving picture to be captured for subsequent storage as a still picture in the system; Figure 3 shows an arrangement for realising the system of Figure 1 with additional facilities; Figure 4 shows a part of the overall system of Figure 3 remote from the main store; Figure 5 shows in more detail the picture integration process, of a preferred embodiment, and Figure 6shows an alternative integration configuration.

In the system of Figure 1, each still picture 10 (e.g.

a photographic slide A) is recorded on the video tape recorder 12 several times (shown in the example as four times, though this number would typically be higher) via T.V. camera 11. The repeated picture information is available for read out from VTR 12 when required and the sequence for a particular picture is received by picture integration processor 13 which effectively integrates the information from each of the pictures in the sequence to provide an enhanced picture in which noise due to the less than perfect tape storage medium is substantially eliminated due to the essentially random nature of such noise. Thus a single picture A is once again available at the output of processor 13. The next picture B would be repeatedly recorded and available for processing in a similar way so that a complete picture library would be built up on the tape.A standard 1 hour tape would be used to store several thousand still pictures each repeated several times.

Each picture would be provided with an index number and accessible via an identification addressing mechanism. Tape machines are provided as standard with an interface for computer control so that editing can take place and frame numbering sequences are also provided as standard in these machines.

The picture processor 13 as described in more detail below, can be realised by providing a solid state store and a noise reduction mechanism allowing picture integration. The integrated picture information may be taken directly from the output of the processor 13, ore more usually would be temporarily stored on a disc 20 to provide an immediate access store for a few of the pictures on the tape to allow the producer to use the retrieved pictures during live broad-casting (or for intermediate storage prior to re-taping), the disc storage quality being sufficiently good not to require subsequent noise reduction. The tape on VTR 12 can also be used as a master to allow duplication on VTR 21. Any noise will be eliminated when the tape is piayed back through the VTR 12 and the sequentially stored picture information integrated in processor 13.

Although the above system has been described as reducing tape noise, any other sources, (e.g. camera noise) would be also attenuated.

In the modified system of Figure 2, a frame store 15 is provided between the camera 11 and VTR 12, to allow a frame from a moving picture to be captured, this still picture then being repeatedly recorded on the tape as before.

The system of Figure 1 is shown in more detail in the Figure 3 embodiment which also has the facility for transmitting the picture information over a telephone wire using modem 29 and slow rate data access from the solid state store within the processorl3.

As previously explained, each still picture 10 is recorded many times on the tape via the camera 11.

Typically a repetition of between 8 and 16 identical frames are selected to be recorded successively by the VTR 12 from the still picture and the position they are recorded at is identified for example by the frame number on the tape, which may be referred to as the tape address. Standard electronic editing systems have a provision for undertaking this function and it is only necessary to provide the electronic controls to command the operation to take place in the required location. A time code generated by the standard VTR may be used to identify the frame for later recall. This code accompanies the video data.

The tape machine 12 records the complete library of still pictures as necessary and identifies the position on the tape as each picture is allocated.

Each standard one hour tape will accommodate approximately ten thousand separate still photographs, repeated eight times. At the beginning of the tape roll, a library index is provided, which identifies the tape address of any required photograph. During operation reference is made to the index which is loaded into the computer memory 15 and access subsequently made by reference to the computer memory. Computer interfacing to VTRs is a standard function for such recorders.

The standard tape machine 12 becomes the main archive record. Access to any picture on the tape is as fast as the tape machine can reach the correct spot and move into a replay mode. This may typically be one or two minutes and is unlikely to be fast enough to act as the method for on-air retrieval.

Data Retrieval is provided by the processing system 13 which accepts the input from the tape machine and includes a frame store 18 into which the tape replay data may be transmitted (shown passing via time base corrector 14 and decoder 16 for decoding Y, I, Q signals). A suitable frame store may be constructed from MOS devices according to our British Patent Application 6585/76 (U.S. Patent Application 764, 148). The capacity of the frame store will be sufficient to store only one complete television frame the information having been converted into digital form as required. However, at each picture point location there will be sufficient data storage to add together the multiple inputs from the successive identical records stored on tape.Thus, if there are eight identical records and each picture is digitized to an accuracy of eight binary bits, the capacity at each picture point in the frame store will be eleven bits using this particular picture integration configuration, as discussed in more detail below with reference to Figure 5.

In order to regenerate the picture suitable for transmission or for inspection, the contents of the frame store is effectively divided by the number of pictures repeated i.e. in this case one-eighth of the total content of each location is utilised. The data so generated may then be recorded in standard digital format on a disc 20 which has sufficient capacity to store perhaps 10 - 100 slides in standard computer compatible form (typically a header code followed by the data and a parity code). Access to the digital disc is in the region of milliseconds and may be used to generate data which is transferred into a frame store, so that pictures may be reconstituted in the frame store as fast as the programme sequence for broadcast requires. It may, for example, be possible to generate between 1 and 5 new pictures per second using standard computer data disc equipment.

Although the frame store 18 provides the video to the system output at normal T.V. rates, reading into the disc 20 has to be at a slower rate because of the limited capabilities of the disc. This can be simply catered for by having the read and write clocks operating independently each locked to the appropriate frequency.

Although the frame store which contains the data for display is shown as comprising the same store used for integration, this may alternatively be a second frame store depending upon the choice of the designer. Data from the frame store is then reconverted into analogue format using a digital to analogue converter 22 using standard techniques so that the information is suitable for direct input to a television system via encoder 23.

Although the system of Figure 3 is shown as receiving a still picture via the camera 11, it is possible as shown in Figure 2 to receive a captured moving picture using the frame store so that the VTR 12 effectively receives information on a still picture.

Use of frame store 18 can be made for this step rather than necessarily providing a separate frame store. Thus the system is flexible to operate in several modes which include: 1. Recording ofstillsvia camera 11 to VTR for recording several times to provide the still archive.

Retrieval is by read out from the VTR 12 via the TBC 14 and decoder 16 to the field or frame store 18 where the integration process occurs over several frames that are the same. Disc storage can be used to allow random and rapid access for use on air when broadcasting.

2. Pictures held on disc 20 can be passed via the processor DAC 22 and encoder 23 to provide video information for storage again on a VTR to permit archive storage on this information by again storing several times to allow integration on retrieval, as above.

3. Moving pictures pass via decoder 16 to frame store 18 which effectively freezes picture motion to allow a still picture (without integration) to be provided for storage on disc 20 for example. The picture held on disc 20 can be repeatedly stored on the VTR as described in mode 2 above.

The system described above will operate under the control of a computer 15 (for example a standard DEC LSI11 mini computer with associated disc). The computer provides sequential access to the desired frames retrieved from the archives store as well as standard formatting of the slowed down data for recording on the conventional computer data disc in the sequence which provides access required in the order for broadcast purposes. A control VDU and keyboard 25 may be used to provide input means for the computer to specify frame numbers etc. The noise reduction arrangement 28 improves image quality, by using integrated picture information.

Interfacing and accessing the various elements in the system is by using standard techniques as described for example in U.S. patent number 4,148,070.

It is also possible to transmit the contents of either the archival store or the digital data disc via a standard computer tele-communications link (e.g.

Modem 29) to a second remote system, which includes a similar computer, data disc and frame store. An example of such a system is shown in Figure 4. Data is received from the master station over a data link which may operate at any of the standard communications rates and in practice may be 9,600 bands. The data is reassembled by the remote station by means of a computer 41 receiving data via modem 40 into a form for storage on the remote data disc 42 and subsequently for use in a broadcast programme by access from the remote data disc to the remote frame store 43 and thence via DAC 45 and encoder 46. A remote control VDU and keyboard 44 is shown provided for processor 41.

A number of such slave units systems shown in Figure 4 may be positioned remotely from the master equipment and provided with access to the master archive.

Thus the invention is concerned with a system using a multiplicity of identical recordings on tape, which are then entered into a noise reduction system using picture information integration. The use of the relatively inexpensive tape medium is now possible with such a system to provide a quality not obtainable by standard tape recording methods.

As already referred to concerning Figure 3, the 8 bit picture data from identical frames used for the picture integration, requires a frame store with a capacity of 11 bits as now described with reference to Figure 5. In this type of picture integration arrangement the incoming video (from decoder 16 of Figure 3) is in 8 bit form and passes via adder 50 to the frame store 51. Assuming the same picture has been recorded eight times then any picture point will effectively be stored frame by frame till the eight frames are stored. As each frame is stored, the contents at present in the store 51 is added to the incoming data in adder 50. Thus assuming a particular incoming picture point is at a peak white level of 100 then after 8 frames the level stored in the frame store 51 will have increased to 800 (i.e. a gain of 8).

This is why 11 bits of storage is used to provide this capability of the increase in gain. To provide unity gain from the system, the store output passes to multiplier 52 which is selected to multiply the data by a coefficient of 1/8 in the case where 8 frames of each picture are processed.

Although this type of noise reduction system is preferable it would be possible to use other noise reduction schemes, however, as shown in Figure 6, the quality of the final image would not be as high because the noise reduction multiply process is effected frame by frame rather than on all frames together at read out. In this system only 8 bits of frame storage are required in store 51. This can be seen since the multiplier 52 is provided between adder 50 and store 51. With the coefficient for the multiplier selected to 1/2 then the store will receive only half of the sum of the incoming and stored data.

Thus in the case of a picture point at a peak white level of 100 then at the end of one stored frame the stored value will be 50, the next frame 75 and the next 87.5 etc until after 8 frames it will be approaching 100. Whilst this arrangement requires a store with less storage capability the noise reduction capability is also less.

The digital adder 50 and multiplier 52 can be constructed in known manner as described for example in U.S. patent application 841,519.

The noise reduction arrangements of Figures 5 and 6 could expediently be duplicated to provide handling of both the luminance and chrominance components of the video data if the data is decoded prior to processing.

In a system using the Figure 5 arrangement in which it was desired to vary the number of frames from each picture to be stored to change packing density of the tape or the degree of noise reduction for example then the coefficient selectable could be stored conveniently in a read only memory (ROM) for use with the multiplier (as described in the aforementioned patent application for example).

The use of a digital video tape recorder in the place of the analogue recorder does not eliminate the need for noise reduction as we believe that errors on the digital VTR will give rise to picture disturbance from a number of sources, including tape error.

Another aspect of the invention is concerned with a system and method used to generate a master archive station and a simpler remote station, which can communicate with the archive over data links.

In the description of this system, it has been assumed that the video tape recorder is provided with its own time base corrector 14. The archival retrieval system may, however, incorporate an integral time base corrector working on one of the principles described for example in patent 1,465,314 or patent application 3207/76.

The television picture may be maintained in composite form throughout the process. However, the preferred embodiment described utilizes composite recording on the video tape, followed by decoding by standard methods into chrominance and luminance components (Y, I, Q) before undertaking noise reduction in the frame store. Decoding may be either analogue or digital according to the preference of the designer.

Claims (25)

1. Astill picture storage system including: storage means for storing a plurality of picture information blocks, each block derived from and representing one and the same still picture; and picture integration processing means for integrating the information contained in the blocks to provide noise reduced picture information at an output thereof.

2. A system as claimed in claim 1 wherein the processing means comprises an integrating frame store for storing information on each of the blocks and noise reduction means for integrating the information held in the frame store to produce an enhanced picture.

3. A system as claimed in claim 2, wherein the noise reduction means comprises an adder for adding incoming picture information to stored picture information and a multiplier for multiplying the stored information by a selected coefficient.

4. A system as claimed in claim 2 or 3, wherein a temporary store is provided for storing the integrated picture information from at least one still picture to allow rapid picture display.

5. A system as claimed in claim 4, wherein the temporary store comprises a video storage disc.

6. A system as claimed in any one of claims 1 to 5 wherein the storage means comprises a video tape recorder and a time base corrector is provided to correct errors on the outgoing information therefrom.

7. A system as claimed in any one of claims 1 to 6 including retaining means for capturing information on a moving picture to allow repeated storage of still picture information held in the retaining means.

8. A system as claimed in claim 7 wherein the retaining means comprises a solid state frame store.

9. A system as claimed in claims 7 or 8 wherein a decoder is provided to separate incoming picture information into luminance and chrominance components prior storage in the retaining means and an encoder is provided to recombine the luminance and chrominance information into a composite video signal prior to the system output.

10. A system as claimed in claim 9 wherein the output of said retaining means is in digital form and a digital to analogue converter is provided to convert the picture information into analogue form priorto receipt by the encoder.

11. A system as claimed in any one of claims 1 to 10 wherein transmission means are provided to allow communication of the processed infor,mation to a remote location.

12. A system as claimed in claim 11 wherein the transmission means comprises a modem.

13. A system as claimed in any one of claims 1 to 12 wherein control means are provided to control the storage and processing of the picture information.

14. A system as claimed in claim 13 wherein the control means includes a computer and means for accessing the computer to select a desired system function.

15. A system as claimed in claims 11 to 14 wherein remote receiving means are provided for receiving the information, and remote storage means are provided to hold the received information.

16. A system as claimed in claim 15 wherein the remote storage means includes a solid state store and a video storage disc.

17. A system as claimed in claim 15 or 16 wherein the remote receiving means comprises a modem.

18. A method of storing still pictures on a storage medium comprising storing a plurality of blocks of picture information, each block being derived from and representing one and the same still picture and integrating the information contained in these blocks when retrieved from the storage medium to provide noise reduced picture information.

19. A method as claimed in claim 18, wherein the integration step comprises adding the incoming and stored picture information from each of the blocks and multiplying the added information by a selected coefficient after storage.

20. A method as claimed in claim 18 or 19 including correcting any timing errors on the information retrieved from the storage medium.

21. A method as claimed in claims 18, 19 or 20 including temporarily storing the noise reduced picture information from selected still pictures on a separate storage medium to allow rapid access thereto.

22. A method as claimed in any one of claims 18 to 21 including capturing information on a moving picture to allow storage of the sequence of the same still picture to be effected.

23. A method as claimed in any one of claims 18 to 22 including transmitting the integrated picture information to a remote location, receiving said transmitted information and storing the received information for subsequent read out.

24. A still picture storage system substantially as described herein and with reference to the examples shown in the accompanying drawings.

25. A method of storing still pictures substantially as described herein.