Abstract: In a film scanner, noise caused by fluctuations in the intensity of a light source 100 are corrected by taking a sample 175 of the light source and correcting the image read from, or written to, the film with respect to the sample. Preferably, the sample is routed around a film gate 105 and has a similar optical path as the image sample 125. In this way, noise due to variations in the optical path and additional electronics 185 may also be corrected.
Abstract: Film unsteadiness in a flying spot film scanner (10) is measured by reference to film image movement based on a measure of the direction of movement acquired by examination by a movement compensator 30 of spatial and temporal differences around a given pixel. A correction signal is generated and applied as a feedback signal to the X and Y circuits of the scan generator (20).
Abstract: A film scanner scans a frame of film three times by reciprocating a clapper gate assembly (160) holding the film (50) past a solid state line array sensor (210). Successive scans are in an opposite sense to the previous scan and R,G,B filter wheel (40) is placed in the optical path and advanced for each scan so that separate high resolution R,G and B scan are produced which can be combined to form a high resolution video signal.
February 1, 1995
Date of Patent:
July 1, 1997
Rank Cintel Limited
Peter Richard Swinson, Graham Malcolm Alexander Barber
Abstract: A telecine uses a flying-spot scanner to derive video images from a film. A scan control circuit is used to control the scan of the flying-spot to introduce special effects. Pairs of successive images may be misaligned and a motion vector estimator is used to detect the amount of misalignment. This produces a shift vector for an image stabilizer to shift one of the images of a pair. The motion vector estimator also receives data from the scan control circuit relating to any special effect in the images and corrects the shift vector in dependence on this.
Abstract: In a high definition flying spot telecine, noise from photomultiplier tubes and afterglow correctors reaches unacceptable levels at high frequencies. The circuit illustrated applied a conventional gamma correction to low frequency components (at 32) but applies a non-linear characteristic to the high frequency components (at 36). The characteristic is chosen to provide the optimum noise performance for positive or negative film. The two parts of the signal are then recombined by adders 40. High frequency processing is carried out on a multiplex of the R, G and B components to reduce complexity (at 16).
Abstract: A continuous-motion flying-spot telecine has twin objective lenses (13,14) which provide beams to scan two adjacent film frames simultaneously. Two sets of light detectors (16,17) are provided, one for each frame being scanned. The detector outputs are applied to a multiple frame store (23; FIG. 2). The scans can take place at half the normal speed, while a conventional rate signal is read out of the store. Problems caused at high frequencies as a result of afterglow on the CRT (10) can thereby be substantially reduced.
Abstract: In non-linear digital video processing, high frequency components resulting from the non-linearity may appear as spurious low frequencies due to mirror image spectral reflection in the sampling frequency fs. The non-linear circuit may be a gamma corrector (35). The effect of the alias components is reduced by the use of a modifier circuit (50) before the gamma corrector, and a corresponding equalizer circuit (52) after it. The modifier attenuates the high frequency signal components, especially in the region fs/4 to fs/2. The equalizer substantially reinstates the overall frequency response. Both modifier and equalizer may be transversal filters (FIGS. 5 to 8) which, more generally, may be one dimensional or two dimensional (FIGS. 9 and 10). The system is also particularly relevant to progressively scanned sources; including telecine.
Abstract: A film instability compensating system compensates for the effects of film instability in a film gate. The film instability compensation system includes a positional transducer for measuring the position of the film edge relative to a sprocket hole which is maintained in contact with a sprocket tooth by a pressure roller. The positional transducer measures the distance between the film edge and a sprocket hole and then measures deviations from the distance for subsequent sprocket holes to determine a compensation signal. The output of the positional transducer is coupled to a delay unit which delays the signal corresponding to the error at a particular sprocket hole until that sprocket hole reaches the film gate. Signals representative of the cyclic errors caused by the relative lateral displacement of the sprocket holes, are stored in a memory and are applied to a subtractor circuit.
Abstract: A video signal is recorded on unexposed cinematographic film by shining light from a light source onto a deformable mirror device (DMD), which comprises a micro-mechanical array of electronically-addressable mirror elements, the elements corresponding to individual pixels. The elements of the DMD are controlled or modulated in response to the video signal. Light is selectively reflected by the DMD onto an image plane containing the film such that the light reaching the film is representative of the video signal.
Abstract: To avoid the effect of blemishes in a CRT phosphor of a CRT film scanner a map is produced identifying areas of the phosphor that are blemished. When a line scan traverses a blemish the signal produced by that scan is inhibited and the area of film is rescanned with the film in a different position relative to the scanner.
Abstract: A control device for a film or tape transport comprises a control knob having a spindle which forms the rotor of an electric motor. The control knob is spun by the operator to generate a drive signal to advance or retard the film or tape driven by the transport system at a speed dependent on the speed of rotation. The rotational speed is sensed and a signal dependent thereupon is produced by a speed detector to control a servo-loop which drives the electric motor. The motor drives the control knob at substantially the same speed imparted by the operator without any further input by the operator. The control knob continues to be driven at this speed until the operator manually accelerates or decelerates the control knob.
Abstract: To avoid burn in a scanning cathode ray tube, the address of the scanning spot at each clock period is recorded in a memory. During each frame period, the logarithms of the number of occurrences of each address are fed to a peak detector. The peak value is used to determine a maximum allowable beam current for the next frame. In another embodiment, the number of occurrences of each address during a line period is monitored and if this number exceeds a given number the CRT is blanked.
Abstract: Compensation for phosphor burn in a CRT scanner is achieved by offsetting the scan by half a line spacing on alternate scans when the film is stationary in the scanner. To avoid unpleasant effects the offset scan output is supressed and the previous frame output frozen in the frame store 24. The previous frame is output again from the frame store in place of the offset scan output.Offset scanning is not performed when a control adjustment is made to avoid a juddering effect on the displayed output.
Abstract: Two photomultipliers (14,16) are arranged one on either side of a CRT (10) primary optical axis adjacent the imaging lens. High frequency components of the detected CRT brightness signal from the two photomultipliers are applied to the "gate" 32. When the signals are equal, one or other of the signals will be selected by the "gate". When the signals are unequal, the lower one will be rejected. Thus signals caused by faceplate (22) dirt are eliminated, since they appear displaced in time from the photomultipliers, due to the spacing of the dirt from the scanning beam and the spacing of the photomultipliers. Phosphor grain and blemish signals occur at the outputs of the photomultipliers simultaneously and are allowed through the "gate" to provide correction and attenuation of these unwanted signals.
Abstract: A sampled input signal, e.g. a video signal, is processed to provide output signals appropriate for positions between input samples by interpolating between the input samples using an interpolating transversal filter (110) and filtering the interpolated signal with a second filter (150) the gain of which increases with increasing frequency. The coefficients of the interpolating transversal filter are chosen so as simultaneously to compensate the frequency response of the second filter and to provide a desired position offset of the output samples with respect to the input samples. The interpolation and filtering steps may be reversed in order. Surprisingly the interpolation is improved in quality when it incorporates a de-emphasis operation in this way. The sampling may be the sampling achieved by the video signal line structure. A non-linear circuit (140) such as a gamma corrector may be interposed between the interpolator and the equalizer.
Abstract: In order to correct for the afterglow or flare in a flying spot telecine, an afterglow or flare correction circuit comprises a series of stages each of which calculate the proportion of the video signal at any one scan location (e.g. pixel) which is attributable to afterglow or flare from successive previously scanned locations or adjacent locations respectively. Each processing circuit comprises a delay, a multiplier for multiplying the delayed signal by a scaling factor dependent on the amount of decay of the delayed signal or the flare at that location and a substractor for subtracting the output of the multiplier from the measured video signal. The output of the corrector subtracts a portion of the output from the previous scan locations in accordance with the stored scaling factor for that location. The scaling factor is derived over a number of video frames. Each measurement is held in an accumulator and averaged to counter noise errors.
Abstract: A telecine can be adapted to write video signals onto film. The film gate and flying spot scanner are enclosed in a light-tight shield and a four-segment (R, G, B, and clear) color filter wheel is interposed in the optical path between the scanner and the imaging optics. The CRT grid is modulated sequentially by R, G, and B components of the video signals which are preprocessed for shading and color errors. The film may be scanned a number of times under the modulation of each component, and displaced in both X and Y directions to increase resolution. In a preferred embodiment, the scan is displaced by 1/4-pixel for each of four scans to increase horizontal resolution and, for each horizontal displacement, four scans are performed, spaced 1/4-line apart, to increase vertical resolution. Thus, each frame is scanned 16 times per color component, and 48 times in all.
Abstract: A plurality n of digital video data streams are individually latched into respective input latches 11.sub.1 to 11.sub.n by a first clock signal LPClk. Two out of n select signals are applied by a selector 16 to enable inputs 14 of the input latches 11.sub.1 to 11.sub.n to select alternate half clock cycles of latched video data and to output such video data to a common bus 19 which supplies two output latches 20 and 21 latched respectively by an antiphase clock signal FLPClk and the signal LPClk so that one of the selected streams is latched into latch 20 as foreground and the other into latch 21 as background. Further latches 31 and 32, and 33 and 34, may be employed to bring the foreground and background streams into relative synchronism.
Abstract: A continuous-motion line-array telecine has a solid-state sensor comprising linear array sensor elements (101, 201, 301). For multi-standard operation compensation is provided for vertical misregistration due to different linear array sensor positions as seen at the sensor plane. The compensation is provided by relative delays (160, 260, 360) corresponding to vertical scan shifts of integral numbers of lines, and vertical interpolation circuits (110, 210, 310) for interpolating between lines for compensating any misregistration equivalent to any residual non-integral vertical scan spacing.
Abstract: In a flying spot telecine including cathode ray tube scanning circuit for generating flying spot and a photodetector for receiving light transmitted by a film strip being scanned by the telecine, a control circuit is provided for causing the CRT scanning circuit to scan an area (18) corresponding to the position of one or more perforations (16) in the film strip (10) being scanned. The output from the photodetector during a scan of the area (18) provides a correction signal for adjusting the video signal level. Preferably, the scan of the area (18) is performed during line blanking or frame blanking periods.