GB2140243A

GB2140243A - Process for the television scanning of films

Info

Publication number: GB2140243A
Application number: GB08411245A
Authority: GB
Inventors: Dieter Poetsch; Volker Mabmann; Jurgen Heitmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1983-05-21
Filing date: 1984-05-02
Publication date: 1984-11-21
Also published as: GB2140243B; DE3318658A1; GB8411245D0; DE3318658C2

Abstract

In a line-by-line TV scan of a continuously moving film, expansion or compression (i.e. ZOOM) of the frames, both horizontally and vertically, may be provided by change of the line clock and horizontal (pixel) clock frequencies for reading in to digital main store (6) via entry buffer (7) digitized (3) data from sensor (1), and reading out via exit buffer (8) data to be converted to analogue (11). Extra lines may be inserted by interpolation (9) and the lines may be re-ordered to provide interlace. Picture shifts may be introduced by relative delays in starting times of entry and exit scan. Colour can be handled by scanning three images with separate sensors, the beam being split according to colour. <IMAGE>

Description

SPECIFICATION Process for the Television Scanning of Films The invention is based on a process for the television scanning of films according to the precharacterising clause of the main claim.

In the television reproduction of cinema films, it has proved expedient to reproduce the film frames not only as the full film size, but also, in so-called zoom reproduction, as a reduction of the film frame or as an enlargement of an excerpt of this, and it should also be possible to carry out on the screen a shift of position of this film frame of different size. Such zoom reproductions of cinema films can be carried out by means of mechanical/optical or electronic processes. In a storage-tube film scanner, this is possible, for example by mechanical/optical means, by varying the size of the image at the signal electrode of the pick-up tube by adjusting the zoom lens.

In a telefilm scanner with semiconductor line sensors (such as, fc example, as described in German Offenlegungsschrift 2,921,934) or with area sensors, mechanical/optical methods are also adopted, as in the case of storage-tube film scanners. However, these methods are expensive in mechanical terms and susceptible to dust, impair the quality of the optical image and do not allow inertia-free adjustment or variation of zoom reproduction.

The object on which the invention is based is, therefore, to provide a process for the television scanning of films, with the possibility of zoom reproductions carried out purely electronically.

The advantage of the process according to the invention, having the characterising features of the main claim, is that the zoom reproduction of film frames takes place free of inertia, and there is no need for a construction which is expensive in mechanical terms and susceptible to wear.

As a result of the measures listed in the subclaims, advantageous developments and improvements of the process mentioned in the main claim are possible.

An exemplary embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. In the drawing: Figure 1 shows a block diagram for carrying out the process according to the invention, Figure 2 shows graphs to represent the variation in the horizontal frequency as regards the expansion factor (Kv).

Figure 1 illustrates a semiconductor sensor 1, for example a line or area sensor, which scans a film which is not shown in the Figure. To clarify the invention, only one sensor is provided in this block diagram, but the use of the invention does not depend on whether colour or black-and-white televison is used for the film scanning. In the case of colour television, the one sensor is preferably replaced by three sensors onto which a light is projected by means of a colour-separtion device known per se.

The output signals from the sensor 1 are amplified, and, if appropriate, undergo various corrections, known per se in the television art, in a video processor 2. Subsequently, the previously analog signals are converted into digital signals in an analog/digital converter 3. As is known, digital signals can be stored reliably and without a loss of quality. For this purpose, the output of the analog/digital converter 3 is connected to an image store 4. This image store 4 consists, here, of a main store 6 and a preceding and a following buffer store 7 and 8. In the image store 4, at least the content of one full television picture including the colour information can be stored. At the output of the image store 4, one line interpolator circuit 9 is connected to a low-pass filter.The digital television signals are read out from the store 4 according to the applied clock frequencies and are fed via the circuit 9 to a digital analog converter 11 in which they are converted into analog signals again and appear at the output 12 of the circuit.

In a clock generator 13, clock signals (fit, f2 and f3) are generated for the read-out of the semiconductor sensors 1 (f,), for the read-out of the analog digital converter 3 and entering in the buffer store 7 (f2), and for the read-out of the buffer store 7 and the entering and read-out of the main store 6 (f3). A further clock generator 14 emits clock signals f,, f,for the read-out of the buffer store 8 and entering in the interpolator circuit 9 (f4) and for the read-out of the circuit 9 and entering in the digital-analog converter 11 (f5). Further control signals for the storage means 1, 4 and 9 are generated by a control logic 16, for example a microprocessor, which is activated by a control unit 1 7 for adjusting the size and position of the frame excerpt. Furthermore, the control logic 1 6 transmits to the clock generators 13 and 14 the signals which are a function of the expansion factors. For synchronisation with other television sets present in a studio, studio clockfrequency synchronising pulses are fed to the image store 4, the clock generator 14 and the control logic 16 via the terminal 18 or 18'.

To achieve a frame reproduction different from normal film-frame reproduction, such as, for example, a reduction of the entire film frame of an enlargement of an excerpt of this, so called zoom effect, various procedures are possible.

If, for example, a charge in size of the reproduced film frame of only approximately +5% is to be made, thus corresponding to an adjustment of the picture ratio, it is sufficient, for the vertical direction, to change the line of horizontal frequency H1 generated by the control logic 16, during the sensor read-out and during entering in the image store 4 or buffer store 7, by the amount of the vertical expansion factor Kv (approximately +5%) in relation to the line frequency H1 which reproduces the film frame completely in the picture ratio 1 :1.33. At the same time, a factor Kv(=H,: H',) > 1 would cause vertical expansion, and KV < 1 would cause vertical compression of the film frame.

However, at the same time, the width of the horizontal blanking interval is reduced with an increasing line frequency H1, because the active line duration (for example, 52 microseconds in the 625-line/50-Hz standard) remains constant. With many frame sizes (for example 35-mm film), it is therefore necessary, because the horizontal blanking interval is barely sufficient even in normal scanning, to increase the clock frequency f1 by a fixed factor during the read-out of the sensors 1 , to obtain a sufficiently wide horizontal blanking interval for these sizes also.As a result, however, the active line duration is reduced, and this then has to be matched to the standard again by means of different entering and read-out clock frequencies 4 and 4 of the image store.

Another possibility of obtaining a change in size of the reproduced film frame in a vertical direction is to vary the sensor clock frequency f1, together with the line frequency H1, to obtain a sufficiently wide horizontal blanking interval. In this process, the active line duration likewise has to be matched to the standard again for all film sizes via the clock frequencies 4 and 4ofthe image store 4. The advantage of this process is that changes in the line frequency H, result in only relatively slight changes in the horizontal blanking interval.

To vary the frame size in a horizontal direction, with the film frame being imaged in full on the sensors 1, the buffer store 7 is operated by means of different clock frequencies for entering (2) and read-out (4), in which case f2=KHX4 with KH being the horizontal expansion factor, so that for this reason also there is expansion (or compression) in a horizontal direction.

When the optical zoom effect is simulated by electronic means, frame expansion can be carried out either during entering in the main store 6 or during read-out from this.

Frame expansion during entering in the main store 6 is achieved by increasing the horizontal frequency and to maintain a sufficient horizontal blanking interval it is necessary also to increase the clock frequency fr of the sensors 1. If the main store cannot process different clock frequencies during entering and read-out, a buffer store 7 is provided for matching the active line duration to the standard (for example, 52 microseconds). The buffer store 7 is clocked at 4=Kvx4 during entering and at 4 during read-out (for KH=l).

Horizontal frame expansion is carried out at 4=KHXf3 during entering in the buffer store 7 and at4 during the read-out of the picture elements from the buffer store 7 (for KV=1). In this process, it is always assumed that 1 > 2. Since here the square of the zoom factor Z=KH=KV for the clock frequency f -Z24 is entered in the buffer store 7, limits are placed on this process by the sensor and analog/digital converter band width which is possible at the present time.

A shift of the picture excerpt on the screen can be carried out in a vertical direction by means of an appropriate delay of the vertical starting pulse V1 which is fed to the main store 6 and which is transmitted by the control logic 1 6. The horizongal shift of the picture excerpt can be carried out by an appropriate selection of the linestart information signal H1 which is fed to the image store 4 and which is likewise transmitted by the control logic 1 6.

Frame expansion during read-out from the main store 6 is achieved in a vertical direction essentially by the insertion of interpolated line signals. The expansion factors obtained as a result are always integral, for example, with KV=2, every second line is interpolated, and with Kv=3 two interpolated lines are inserted between every two existing lines. Expansion factors lying between these values are obtained by means of a change in the line frequency H1 and a corresponding change in the clock frequencies 1 and f2.

In this respect, the graph according to Figure 2a represents the sensor clock frequency f, as a function of the vertical expansion factor Kv. Here, the maximum value of the sensor clock frequency f1 falls with an increasing expansion factor according to the ratio of two adjacent integral expansion factors. A further narrowing of the range of variation of the sensor clock frequency fez can be achieved by means of a combination of adjacent interpolation patterns (thus, for example, KV=1.5; that is to say one interpolated line follows two original lines).

When the interpolated line signals are formed in the circuit 9, the read-out from the main store 6 into the buffer store 8 is interrupted line by line by means of the vertical starting pulse PV2' Horizontal expansion is carried out in the buffer store 8, during entering or read-out, by means of the linestart pulses H3 or H2 which are suppiied.

The expanded signal is subsequently filtered digitally by means of the low-pass filter in the circuit 9.

In vertical expansion during read-out from the main store 6 with a fixed sensor clock frequency f1 and a fixed analog/digital converter clock frequency 4, the width of the horizontal blanking interval changes as a function of the line frequency H1 even before the main store 6. When an increase, in the line frequency H1 is not possible, then every second line is already being interpolated when the vertical expansion factor is Kv > 1, so that the line frequency H1 for entering in the image store 4 can be halved (H1' > H1 > 0.5 H1,). Thus, a sufficiently wide horizontal blanking interval is always guaranteed.

The graph according to Figure 2b represents the line frequency H1 as a function of the vertical expansion factor Kv. As can be seen, whenever the interpolated lines to be inserted between two original lines are increased, the value of the line frequency jumps from H1' to 0.5 H1, and, with an increasing vertical expansion factor Kv, slowly rises again to the value H 1 At the same time, the shift of position in a horizontal direction is determined by selecting the line-start picture element by means of the information signal H2 from the buffer store 8. The shift of position in the vertical direction is carried out by appropriately determining the read-out starting point by means of the information signal PV2 from the main store 6.

Claims

1. Process for the television scanning of films by means of line or area sensors onto which the frames of the continuously moving film are imaged, the film being scanned line by line without line interlacing and being converted by means of an image store into a standard television signal with line interlacing, characterised in that for expansion or compression of the scanned film frames both in a horizontal and in a vertical direction (so-called zoom effect), and if appropraite for a shift of the frame centre during the television reproduction of the film on the screen, the clock and/or horizontal frequencies for activating storage means are varied selectively during entering and during readout.

2. Process according to Claim 1, characterised in that the expansion in a vertical direction of the video signal generated by the line or area sensors (1) is carried out by increasing the horizontal frequency during the read-out from the sensors (1) and during entering in the image store (4), and the expansion of the video signal in a horizontal direction is carried out by means of different clock frequencies of the image store (4) during entering and read-out, the read-out clock frequency being reduced by the amount of a horizontal expansion factor (KH) in relation to the entering clock frequency.

3. Process according to Claim 1, characterised in that the compression in a vertical direction of the video signal generated by the line or area sensors (1) is carried out by lowering the horizontal frequency during the read-out from the sensors (1) and during entering in the image store (4), and compression of the video signal in a horizontal direction is carried out by means of different clock frequencies of the image store (4) during entering and read-out, the read-out clock frequency being increased by the amount of a horizontal expansion factor (KH) in relation to the entering clock frequency.

4. Process according to Claim 2, characterised in that for the purpose of fine adjustment of the vertical expansion of the video signal generated by the line or area sensors (1) the horizontal frequency is increased during the read-out from the sensors (1) and during entering in the image store (4), and for the purpose of approximate adjustment of the expansion interpolated line signals are inserted during the read-out from the image store (4), and adjustment of horizontal expansion is carried out by means of different clock frequencies of the image store (4) during entering and read-out, the read-out clock freuqency being reduced by the amount of a horizonal expansion factor (KH) in relation to the entering clock frequency, and in that the video signal obtained in this way is filtered in a low-pass filter.

5. Process according to Claim 2, characterised in that, in addition, to obtain a sufficient horizontal blanking interval, the clock frequency is increased during the read-out of the sensors (1 ) and during entering in the image store (4), the read-out clock frequency of the image store (4) being reduced in each case by the amount of a fixed factor or by the amount of the vertical expansion factor (Kv) in relation to the entering clock frequency.

6. Process according to Claim 4, characterised in that, to obtain a sufficient horizontal blanking interval for expansion, at least one interpolated line is added during the read-out from the image store (4), and in that the horizontal frequency is initially reduced in a jump according to the number of added lines and, with an increasing expansion factor, rises again up to the original value, thereafter with a further increasing expansion factor, being reduced in a jump again as a result of the addition of further interpolated lines.

7. Process according to Claim 4 and 6, characterised in that to form the interpolated line signals the read-out from the image store (4) is interrupted line by line.

8. Process according to Claim 1, characterised in that the vertical shift of the changed frame size is effected by means of an appropriate delay of the vertical starting pulse during entering in or read-out from the image store (4), and the horizontal shift of the changed frame size is effected by means of an appropriate selection of the line-start picture element during the read-out from the image store (4).

9. Process according to Claim 1, characterised in that both the changes in the frame size or of the frame excerpt in a horizontal and vertical direction and its possible shift are carried out by means of a manually adjustable control logic (16).

10. Process according to Claim 9, characterised in that the manual adjustment of the control logic (16) is preprogrammable.

11. Process according to Claim 9, characterised in that the adjustable control logic (26) transmits both the different horizontal frequencies and starting pulses for the storage means (1, 4, 9) and the signals of the expansion factors for the clock generators (13, 14) generating the clock signals.

12. Circuit for carrying out the process according to claims 1, 9 and 11, characterised in that the sensors (1) are connected to an analog/digital converter (3), in that the analog/digital converter (3) is connected to the image store (4), in that the image store (4) is connected via a line interpolator circuit (9) with a lowpass filter to a digital/analog converter (1 1), at the output (12) of which the video signal changed in terms of frame size can be picked up, and in that the clock generators (13, 14) and the control logic (16) are provided for controlling all the circuits located in the path of the video signal.

13. Circuit according to Claim 12, characterised in that the image store (4) consists of a main store (6) and a preceding and/or a following buffer store (7, 8) which are likewise activated by the clock generators (13, 14) and the adjustable control logic (16).

14. A process for the television scanning of films substantially as hereinbefore described with reference to the accompanying drawings.

1 5. A circuit for the television scanning of films substantially as hereinbefore described with reference to the accompanyirLg drawings.