GB2050748A - Generating partial TV image of overall picture - Google Patents

Abstract

An overall large field of view image is viewed by a smaller field of view TV camera and thereby divided into a plurality of individual images EBI to EBVIII. The individual image signals after being digitized, and possibly via a mass store M.S.P., are stored in respective stores B1 to Bm. B1 to Bm can be strobed in synchronism by a clock generator TG, and information from B1 to Bm is passed through selective delay means VZ1 to VZm, which introduce no delay or a line return time delay, to lines 1 to 4. A set of switches ES1 connect first the delayed output from Bx and then the undelayed output from B(x + 1) to a monitor M1 via a digital-to-analog converter DA1. The scanning of M1 is suitably delayed relative to the strobing of B1 to Bm, to give a partial image, of size equal to the individual images, which can be selected from anywhere inside the overall image. The individual images in B1 to Bm can be processed by a computer to correct for geometric and grey scale distortion in the TV camera, using iterative comparisons with a reference partial image EB REF. <IMAGE>

Description

SPECIFICATION Generating partial tv image of overall picture The present invention relates to the generation of an image on a display monitor of any desired portion of an overall image which is formed by juxtaposing several individual images.

In our prior application No. 2 014 01 5 A filed 17th January 1979, a system of this kind is described. In broad terms, in that system the overall image (which is in a sense only notional, since the whole of the overall image is not displayed as such) has a randomly selected portion thereof (of size equal to the size of the partial or individual images) displayed on a display monitor. This involves providing delay circuits which can be selectively inserted in the outputs from the several TV cameras which generate the individual images forming the overall image.The delays are equal to the line return times, and by delaying the output from a camera showing the left-hand part of the portion of the overall image to be selected and not delaying the output of the camera showing the right-hand part of that portion, and suitably adjusting the timing of the display monitor relative to the cameras, the desired display can be achieved.

In addition to the high cost of using a separate camera for each individual image forming the overall image, which this known system entails, this system also imposes stringent requirements on the switching circuits since rapid switching of analog TV signals has to be performed. Also, there is no possibility of correcting for any distortion of the image geometry.

The object of the present invention is therefore to provide a method for generating a monitor display of a partial section of an overall image which involves a lower cost, being realized with simpler circuit means, and which allows correcting measures to be taken.

Accordingly the present invention provides apparatus for generating a monitor display consisting of a randomly chosen portion of an overall image consisting of a plurality of individual images arranged in a matrix, comprising analog to digital converter means for digitizing the individual images produced by at least one television camera, storage means for storing the digitized individual images, and means for selectively reading out and displaying the image information on the monitor.

Apparatus for generating a monitor display of a partial section of an overall image in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of the details of part of the apparatus, and Figure 2 shows the partial and overall images and a general block diagram of the apparatus.

Referring first to the upper part of Figure 2, this shows an overall image EBI to EBVIII formed by 8 individual scannings of corresponding portions of a scene, and the size of the partial image EB REF which is to be displayed on a display monitor. This partial image can be placed anywhere within the overall image.

Figure 1 shows four image storage means B1 to Bm in which for instance the individual images EBI to EBVIII shown in Figure 2 are stored. The individual images in the image storage means B1 to Bm are loaded by means of a load device LA and a computer R1 from a mass store MSP. The mass store MSP herewith may be for instance a tape or disc storage means. The information is stored in the digital image storage means B1 to Bm in such a way that, on the production of clock signals by means of a clock generator TG and with corresponding strobing of said image storage means, the information representing a video signal but in digital form may be taken from the output.

The outputs of the image storage means B1 to Bm may be connected to digital switches ES1 to ESn either directly or by means of delay elements VZ1 to VZm. By means of the digital switches ES 1 to ESn, switching between the individual images EB1 to EBVIII may be achieved so that at the output of the digital switches ES 1 to ESn digital signals of the image information are provided. The digital switches ES1 to ESn are controlled by address transmitters AG 1 to AGn via addressing circuits AS 1 to ASn. The addressing circuits AS 1 to ASn also are strobed by the central clock of the clock generator TG.Digital/analog converters DA1 to DAn connected to the switches ES1 to ESn convert the digital signals into a corresponding analog signal which controls conventional monitors M1 to Mn, so that according to the addressing of the individual images a partial section of the overall image is shown on the corresponding monitor.

From Figure 2 it may be seen that a single camera K1 is sufficient for sequentially recording the individual images EBI to EBVIII and for storing them in the mass storage MSP after a suitable signal conversion in an analog/digital converter W1 and transfer via the image storage means BS and the computer RE. It should be noted at this point that on recording of an image with a camera, different distortions may appear which are due to the design of the camera including its optics. The most important distortions are given by geometrical distortions and grey scale distortions.

With the present method under certain circumstances the image contents is computable or changeable by means of a computing method so that it is possible to compensate for the above stated distortions by means of digital computers.

This will be explained in the following with respect to Figure 2 and the program flow diagram.

PROGRAM FLOW DIAGRAM 1. Digitize EBref and store in MSP. Go to (2).

2. Digitize EBI to EBVIII and store in MSP. Go to (3).

3. Activate correction. Input mathematical description of EBref. Go to (4).

4. Compare EBref, calculate geometry and grey scale, and store in MSP. Load EBn to BS and indicate on monitor. Go to (5).

5. Are all EB's corrected and indicated? No go back to (4). Yes - go to END.

The individual image EB recorded by the camera K1 and digitized by means of the converter W1 is stored in the digital image storage means BS and may be read out into the mass storage MSP by means of the digital computer R1.

By means of the computer R1, it is also possible to read again the information stored in the mass storage MSP and to bring it back to the image storage means BS. From there the image stored in the image storage means BS may, by means of the digital/analog converter DA1, be converted into a video signal, provided with corresponding clock signals, and displayed on the monitor M1.

The shown arrangement further more permits the possibility of processing and improvement of the image contents of the individual images EBI to EBVIII. To this end an individual reference image EBref is recorded with the camera K1, is digitized with the converter W1 ,and is also memorized in the mass storage MSP. With regard to geometrical corrections the individual reference iamge EBref is preferably a scanning-pattern image the mathematical description of which is put into the computer by means of a program. The individual images EBI to EBVIII reside after digitizing also in the mass storage MSP. The digital computer R1 then evaluates the difference between the individual reference image EBref and the mathematical description of the scanning pattern.By means of the difference between the image contents of the digitized individual reference image EBref and the perfect scanning pattern of the mathematical description, the computer R1 evaluates the geometrical distortions of the individual image points of the camera. The computer R1 once having evaluated those differences is able to change by means of these difference the digitized individual images EBI to EBVIII in such a way that the geometrical distortions produced by the camera are corrected.

The same procedure accordingly may be used for the correcting the grey scale distortion. To this end the computer R1 needs as inputs a nominal grey scale for each image point. The difference between the nominal value of the grey scale and the measured value of the grey scale of the individual reference image EBref again is used for correcting the grey scale values of the different image points of the individual images EBI to EBVIII. The computer R1 in this way corrects sequentially the different individual images EBI to EBVIII and then stores those again in the mass storage.

If all individual images are corrected the computer may transfer the corrected images into the digital image storage means B1-Bm (Fig. 1).

Then in the image storage means B1--Bm a corrected overall image is at hand for display of partial sections.

The above described method has the advantage that the image information may be digitally processed and corrected. Moreover for instance the possibility exists to intersect silhouettes of certain objects into the image contents, whereas in contrast in an optical superposition no mixture of the. object and the background image information takes place.

Claims (6)

1. Apparatus for generating a monitor display consisting of a randomly chosen portion of an overall image consisting of a plurality of individual images arranged in a matrix, comprising analog to digital converter means for digitizing the individual images produced by at least one television camera, storage means for storing the digitized individual images, and means for selectively reading out and displaying the image information the monitor.

2. Apparatus according to Claim 1, including a computer for correcting the individual images stored in the storage means.

3. Apparatus according to Claim 2, wherein during the correction the individual image being corrected is temporarily stored in a mass store connected to the computer.

4. Apparatus according to Claim 3, including means for recording an individual reference image by the camera, comparing the individual reference image with a mathematical description of the object giving rise to the individual reference image, and the determination of a correction program from the comparison.

5. Apparatus according to any previous claim including a random delay of the information read out from the storage means and a digital to analog converter for converting that information for display on the monitor.

6. Apparatus for generating a partial TV image of an overall picture substantially as herein described and illustrated.