GB2255252A - System for the storage and distribution of compressed images - Google Patents

Abstract

The system includes a video camera 11 to take an image of a person, the visual image being converted into digital data. The image data is compressed in a CPU 26 so as to occupy at least a quarter of the memory space of uncompressed data and is written to a remote memory storage 16 via a communication link (17). The image can be retrieved and uncompressed by retrieval circuitry 13 and can be subsequently viewed on a VDU 14. A system is also disclosed where multiple retrieval devices can access selected data stored in the remote memory storage 16, the data being read by a selected such device via a selection device (34, fig 3). The system may be used to store images of individuals for use in monitoring/authorising financial transactions. <IMAGE>

Description

IMAGE PROCESSING AND DISTRIBUTION SYSTEM This invention relates to an image processing and distribution system.

The need for a system which enables recordal of an image of a person and which allows subsequent retrieval of that image has long been realised by the retail trade, financial institutions and the police force in particular. For example, such a system could be utilised for the verification of the identity of credit card users.

Hitherto such a system has not been practically possible insofar as it has not been possible to store visual images of persons' faces without a relatively large amount of memory space being necessary and thus to date it has not been possible to store large numbers of images in the available memory space.

It is an object of the present invention to provide a system which is capable of storing a large number of images of persons in a relatively small amount of memory space and which allows this data to be accessed in a simple and convenient manner. Furthermore it is a further object of the invention to provide a system which allows the distribution of this type of data between multiple remote and/or local locations.

According to a first aspect of the present invention therefore there is provided an image processing and distribution system comprising capture means to receive a visual image and to produce data pertaining to said visual image, compression means to compress said image data, storage means to store said data, and retrieval means to retrieve said compressed stored data from said storage means.

With this arrangement it is possible to allow storage of a large quantity of data relating to visual images.

In accordance with a second aspect of the present invention there is provided an image processing and distribution system comprising capture means to receive a visual image and to produce data pertaining to said visual image, compression means to compress said image data, storage means to store said data, at least two retrieval means to retrieve said compressed stored data from said storage means and selector means operable to allow the selection of one said retrieval means to receive said stored data.

With this arrangement it is possible to allow the easy access and distribution of data for display at one or more different locations.

The invention will now be described further by way of example only and with reference to the accompanying drawings of which: Fig. 1 shows a diagrammatic representation of one form of system according to the invention; Fig. 2 shows a block diagram of one form of capture/ retrieval unit for incorporation in the system of Fig. 1; Fig. 3 shows a block diagram of the system of Fig. 2 showing the selection unit; and Fig. 4 shows a more detailed block diagram of a part of the system of Fig. 3.

Referring to the figures, Fig. 1 shows a diagrammatic representation of the layout of an image processing and distribution system 10. The system comprises a video camera 11, image capture circuitry 12, image retrieval circuitry 13, a visual display unit (VDU) 14 and a remote image storage memory 16 linked to the image capture and retrieval circuitry 12, 13 by way of communication network 17. The capture and retrieval circuitry also comprise memory 36, however this memory is of a much reduced storage capability compared to the storage capability of the remote storage memory 16.In practice it is envisaged that the camera 11, image capture and retrieval circuitry 12, 13 and VDU 14 are incorporated in a single capture/retrieval unit 18, and as many of these units as are required in the system are provided locally on site and can be linked to the central remote image storage memory 16 via the communication network to allow reading and writing of data to take place therebetween.

In more detail a capture/retrieval unit 18 for incorporation in a system of the above type is shown in block form in the circuit diagram of Fig. 2 (with the exception of the VDU 14). A video camera 11 is connected to a video digitiser 19 which converts the video signal from the camera 11 into digital form. The digitiser 19 also contains synchronisation separating circuitry (not shown) which can extract the horizontal and vertical synchronisation pulses from the input video signal in order to provide a signal indicative of the line rate of the incoming video signal. The digitiser 19 is connected to a generator and locking circuit (GENLOCK) 21 via a synchronisation switch 22 which in turn is connected to a local synchronisation generator 23.The local synchronisation generator is operable to generate synchronisation pulses either additionally or alternatively to synchronisation pulses extracted from an incoming video signal by the separating circuitry.

The synchronisation switch 22 operates to selectively feed synchronisation signals to the GENLOCK circuit 21 from either the separator or the generator 23 as appropriate and as is described hereinafter.

The GENLOCK circuit 21 includes one or more counter circuits, along with circuits to control the operation thereof, and a phase-locked loop circuit. The GENLOCK circuit 21 generates a clock signal at a multiple of the line frequency of the input video signal. The clock signal thus produced is used to time the conversion of the analogue video image signal to a digital signal suitable for storage in a memory device. The phaselocked loop of the GENLOCK circuit 21 also acts, in conventional manner to synchronise the capture system to the synchronisation pulse frequency of the input video signal. The clock signal increments the counters and count outputs are fed from the GENLOCK circuit 21 to the image memory 24 and represent screen addresses which control where the image data is stored in the memory 24.

The memory device 24 comprises static or dynamic RAM and is linked to the central processing unit (CPU) 26 of the system which reads the image data stored in the memory device 24 and processes such data in a manner to be described hereinafter. The CPU 26 takes data relating to the image and compresses the data. This allows image data as would normally use 16K of memory space to be stored in 4K of memory space. However it will be appreciated that compression of image data in this way will necessarily change the resolution of the image when reconstructed from the compressed data and thus the amount of compression is chosen in accordance with a user's requirements for image display resolution. After having read the image data, and compressed the image size, the CPU 26 writes the data to a remote image storage memory (not shown) via a communication interface 27.The CPU itself also has a limited memory capacity and can store a number of images locally.

A keyboard is linked to the CPU and allows local control over the operation of the CPU.

Retrieval of an image stored in the remote memory is by interrogation of the memory by the CPU 26 via the communication interface 27. The compressed data relating to the image is read by the CPU 26 and is converted back into expanded form. This data is written into the image memory by the CPU. The GENLOCK circuit generates screen addresses to the image memory and this image screen data is fed to the video mixer circuit and synchronisation pulses are extracted from the input video signal by the digitiser 19 and are fed to the video mixer circuit.

These two signals are combined in the video mixer circuit 28 to form a composite video signal which can be displayed on a VDU.

If the input video signal is no longer present then a synchronisation signal is generated locally by a generator 23. This signal is then fed to the video mixer circuit 28 by way of a switch 22. The switch 22 operates to selectively cause the extraction of synchronisation pulses from an incoming video signal, if available, and if not the generation of such pulses in the generator 23.

It may be desired to superimpose on the video signal textual data for example pertaining to the video picture displayed and in this case address signals are generated by the GENLOCK circuit 21 in a form suitable to form address information for a character data memory 29 which stores data in the form of character codes. A character generator 31 is connected between the character data memory 29 and the video mixer circuit 28 in order to convert the stored character codes into pixel patterns which the video mixer circuit 28 can utilise along with the memory address signals and suitable clock signals provided by the clock to form the text signal output.

The text signal is combined with the video signal in the video mixer 28 and a composite image is thus displayed on the local VDU.

Retrieval of image data stored locally in the CPU 26 occurs by writing such image data to the image memory 24 for which address information is provided by the GENLOCK circuit 21. The image data is fed to the video mixer circuit 28 along with synchronisation signals derived from a local synchronisation generator 23, or synchronisation data derived from the local input video signal. In this respect, the GENLOCK circuit 21 also acts to supply the data from the memory 24 to the video mixer circuit 28 in the correct sequence for conversion to an analogue signal capable of producing the desired retrieved video signal. As mentioned above, it will be appreciated that text can be added to the video signal to form a composite video signal via the character data memory 29 and the character generator 31.

A further embodiment of capture/retrieval unit for incorporation in a system of the abovementioned type is shown in Fig. 3. This embodiment is essentially the same as that shown in Fig. 2 with the exception that more than one retrieval device is provided locally which can access the stored image data. Thus a selector unit 22 is included within the capture/retrieval unit, the selector unit 32 consisting of a system selection device 34 which is able to select one of the selector devices 33 associated with each retrieval device thereby to allow writing of data to a particular retrieval device. Thus it will be appreciated that with an arrangement of this type different data can be retrieved by different retrieval devices at the same time.

The layout of each retrieval device is shown in more detail in Fig. 4. Thus the system selection device 34 of Fig. 3 comprises a number of latch circuits 37 and the selector devices comprises respective image and character address multiplexer 38, 39, an interface control circuit 41 and bus transceivers 42, 43.

In operation, the latch circuits 37 are used to access either or both of the image and text memories 24, 25 of a particular output device. The latch circuits are under the control of the CPU subsystem 36 of the capture/retrieval unit shown more clearly in Fig. 3, and thus when it is desired to access data by a particular retrieval device then the CPU subsystem 36 sets the appropriate output in the latch circuits. In this respect each latch circuit has an output for each retrieval device. When the latch circuits output has been set by the CPU subsystem 36 then image and/or character data can be written into the image and/or text memory 24, 25 of that particular retrieval device via the interface control circuit 41 and the bus transceivers 42, 43.To achieve this the CPU 26 generates interface control signals which control the interface control circuit 41 to allow the data to be written into the appropriate memory via the multiplexers 38, 39 and bus transceivers 42, 43. The interface control circuit 41 operates to encode sinals received from the appropriate latch circuit output and also the control signals received from the GENLOCK circuit 21 and CPU 26 of the unit into signals which control the multiplexers 38, 39 and bus transceivers 42, 43 to allow data to be written into the memories of the device.

Various of the latch circuits 37 are also operable to blank image or text from the output of the video mixer circuit by clearing the appropriate output in the latch circuits corresponding to the retrieval device with which the image is to be displayed.

With this arrangement it is possible to allow the mounting of data selectively to a particular output device of a capture/retrieval unit having more than one output.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiments which are described by way of example only.

For example, it will be appreciated that the image data can be displayed on a VDU of an output device in monochrome or colour as desired or as appropriate. In this respect whilst it is possible to compress monochrome image data to an extent whereby it can be stored in 4K of memory space, if a colour image is desired then the comparable memory space occupied by the data corresponding thereto would be 6K.

Claims (19)

1. An image processing and distribution system comprising capture means to receive a visual image and to produce data pertaining to said visual image, compression means to compress said image data, storage means to store said data and retrieval means to retrieve said compressed stored data from said storage means.

2. A system according to claim 1 wherein said capture means comprises a video camera,

3. A system according to claim 1 or claim 2 wherein said capture means includes digitising means which acts to produce data in digital form indicative of the visual image received by the capture means.

4. A system according to any one of claims 1 to 3 wherein the system further includes synchronisation means which acts to produce a timing signal of the same frequency as the line rate of the visual image received by the capture means.

5. A system according to claim 4 wherein said synchronisation means extracts timing pulses from the visual image received by the capture means.

6. A system according to claim 4 or claim S wherein said synchronisation means includes a synchronisation device which acts to produce timing pulses of the same frequency as the line rate of the visual image received by the capture means but independently thereof.

7. A system according to any one of claims 1 to 6 wherein said compression means comprises a central processing unit (CPU) of microprocessor.

8. A system according to any one of claims 1 to 7 wherein said storage means comprises a remote memory.

9. A system according to any one of claims 1 to 8 wherein the ratio of the amount of memory space taken up by the uncompressed image data and the compressed image data is at least 4:1.

10. A system according to any one of claims I to 9 wherein said capture means also includes memory of relatively smaller size than the storage means in which the visual data can be temporarily stored prior to being passed to the compression means.

11. A system according to claim 8 wherein said capture means and said retrieval means are linked to the remote memory by way of a telecommunication link.

12. A system according to any one of claims 1 to 11 wherein said retrieval means comprises a CPU which reads data stored in said storage means and causes expansion of the compressed image data to form retrieval image data.

13. A system according to claim 12 wherein said retrieval means further includes timing means to provide a timing signal for formation of a retrieval image from the retrieval image data.

14. A system according to any one of claims 1 to 13 wherein said means also includes a mixer means whereby auxiliary data e.g. relating to a text image can be added to the retrieval image data thereby allowing a composite image to be formed.

15. An image processing and distribution system comprising capture means to receive a visual image and to produce data pertaining to the visual image, compression means to compress said image data, storage means to store said data, at least two retrieval means to retrieve said compressed stored data from said storage means and selection means operable to allow the selection of one said retrieval means to receive said stored data.

16. A system according to claim 15 wherein said selection means includes multiple latch circuits which allow access by the retrieval means to desired data in said storage means.

17. A system according to claim 15 wherein said latch circuits also act to blank data accessed by the retrieval means from the storage means.

18. A system according to any one of claims 1 to 17 wherein the system further includes a display on which the data received by the capture means, or returned by the retrieval means, can be displayed.

19. A system substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2 or 3 and 4.