Abstract: A method for determining a noise component in a video signal is proposed, in which the difference between a delayed and an undelayed video signal is formed. In order to be able to measure the noise component as precisely as possible, the delayed and the undelayed video signal are assigned to at least two different processing channels depending on their respective amplitude. At least two peak values for the noise signal for two different amplitude ranges are determined from the absolute value of the difference between the two video signals. Furthermore, a circuit is proposed which is suitable for implementing the method proposed.

Abstract: The invention relates to a device for reducing flicker disturbances in a video signal having a temporal median filter and a filter connected downstream. The temporal median filter serves for compensating for brightness fluctuations in the video signal. The filter connected downstream separates high-frequency signal components from the output signal of the temporal median filter and suppresses high-frequency signal components with a high amplitude.

Abstract: A method for determining a noise component in a video signal is proposed, in which the difference between a delayed and an undelayed video signal is formed. In order to be able to measure the noise component as precisely as possible, the delayed and the undelayed video signal are assigned to at least two different processing channels depending on their respective amplitude. At least two peak values for the noise signal for two different amplitude ranges are determined from the absolute value of the difference between the two video signals.

Abstract: The invention relates to a device for reducing flicker disturbances in a video signal having a temporal median filter and a filter connected downstream. The temporal median filter serves for compensating for brightness fluctuations in the video signal. The filter connected downstream separates high-frequency signal components from the output signal of the temporal median filter and suppresses high-frequency signal components with a high amplitude.

Abstract: In a device for reducing noise in image signals, the image signals passing through a temporal recursive filter whose feedback factor is a function of movement in the images represented by the image signals, in order to form the feedback factor for the respective current image, a first and a second factor are combined in such a way that the smaller one of the factors substantially determines the feedback factor. The first factor is formed from the feedback factor of the preceding image, and the second factor is calculated from the difference between the preceding image and the current image.

Abstract: In a device for noise reduction in video signals the video signals are split into at least a local lower frequency spectral content and a local higher frequency spectral content. The higher frequency spectral content is passed through a time filter. The output signal of the time filter and the correspondingly time-delayed lower frequency spectral content are added to together to form a noise-reduced video signal.

Abstract: A video signal-processing device, for example a film scanner, including an arrangement for detecting scratches in images of a video signal. To improve the detection of slant scratches, the arrangement for detecting scratches combines a given number (m) of series-arranged pixels (43, 44) of a video image to form a group (45), and to determine a division of the pixels in accordance with given criteria for each group of pixels and, based on this division, to classify the pixel groups in scratch sections and non-scratch sections.

Abstract: A video signal-processing device includes an arrangement for detecting film scratches. To distinguish slant scratches in the video signal from other scratch-like image structures in a safe manner, the arrangement for detecting scratches is intended to determine whether at least the section of a scratch extends from the lower margin of an image N-1 preceding a current image N into the upper margin of the current image N, and whether at least a further section of a scratch extends from the lower margin of a current image N into the upper margin of an image N+1 succeeding the current image N.

Abstract: A device for processing video signals includes a noise reduction arrangement and a contour correction arrangement. To improve color correction, a color correction arrangement (11) is arranged between the noise reduction arrangement (10) and the contour correction arrangement (12).

Abstract: Method of eliminating interference signals from video signals by means of motion-adaptive transversal filtering, in which the motion is detected in the two-dimensional plane for the purpose of S/N ratio improvement. To this end, the forward and backward-motion signals are combined to a common motion signal and transformed into a polar coordinate signal from which the coefficients for controlling the transversal filter are derived.

Abstract: In a method of reducing the noise in a signal from a motion detector for video signals, in which a part of the amplitude range of the signal below a threshold value is suppressed, the minimum of the signal is determined by means of a control loop, starting with a minimum threshold value. The threshold value is increased when the minimum of the signal exceeds a given value, preferably 0, and is reduced when the minimum of the signal lies below the given value.

Abstract: In a method and a circuit for detecting and concealing video signal errors caused by vertically extending film scratches during television film scanning, an error signal is derived at error locations generated by disturbed pixels and is used in the form of a control signal for concealing errors in the video signal. The error signal is generated only when an adjustable, locally bounded scratch width in the horizontal direction is not exceeded and when each scratch essentially extends vertically, and when the scratch length substantially corresponds to the film frame height. Finally, the disturbed locations in the video signal are replaced by the corresponding low-pass-filtered video signal with the aid of the error signal.

Abstract: A method of reducing noise in the signal of a motion detector for recursive filtering of video signals, in which the signal is median-filtered. A part of the amplitude range of this signal located below a threshold value is suppressed and the signal is subsequently used for forming the factor (k) controlling the recursive filter. In the case of stationary images or images of little motion, the factor (k) is set at a maximum value dependent upon interference pulses occurring in the video input signal (V1) and at a minimum value dependent upon interference pulses occurring in the video output signal (V2).

Abstract: A method of eliminating interference signals from video signals by motion-adaptive filtering, in which method first a motion signal-dependent transversal filtering and subsequently a median filtering is performed.

Abstract: A motion signal is formed by subtracting an undelayed and a delayed video signal and by subsequently forming the absolute value. An amplitude maximum of the motion signal is initially determined within a search window and subsequently a minimum corresponding to the noise peak value is determined from the maximum values of a plurality of search windows.

Abstract: Video signals are supplied as component signals (in which the color signals are not correlated with a color carrier wave) and are stored in a frame memory and read out therefrom in synchronism with supplied reference signals. A FIFO memory is interposed ahead of the frame memory for delaying the video signals in such a way that they can be brought into synchronism with the horizontal phase of the reference signals. The system can be made to operate in a frame mode in which the field sequence and the timing of the synchronizing pulses always agree with those of the reference signal, in a field mode in which only horizontal sychronization is provided and the field sequence can be modified, a line mode in which the input signal is merely delayed into synchronism with the horizontal phase of the reference signal, and a delay mode in which a substitute reference signal is derived from the input signal itself, so that the memory is used merely for delay.

Abstract: A digital oscillator is built around an accumulator which is incremented by a predetermined number N of unit values at every pulse of a sequence of pulses of a reference frequency and the carry output of the accumulator is used to produce the output frequency. In order to eliminate the jitter of that output, the carry signal is supplied to a delay chain, from the output of which a delay is selected in a manner dependent upon the content of the accumulator during the presence of the carry signal in question at the output of the accumulator. The carry pulse times a D register in which the contemporary content of the accumulator is stored until the next carry pulse while being supplied to a calculation circuit for selecting the appropriate delay derived from the D register content and the number of units of accumulator incrementation in use at the particular time.

Abstract: A video noise reducer comprises a full picture memory and provides comparison of corresponding pixels of undelayed and delayed video signals, in which the delayed signal is fed back and mixed which is the undelayed signal at a controllable fader fading factor controlled by the absolute value difference between compared pixels subjected to filtering and other processing. In this noise reducer pixel comparison is elaborated to provide a signal designating the sign of the difference and a temporal (non-spatial) motion detector checks for the predominance of designations of one sign (and the rarity of designations of the other sign) in order to establish the presence of a fading procedure which must not be mistakenly interpreted as a detection of motion in the picture content. The temporal motion detector can be constituted so that isolated designations of a sign opposite to the preponderant sign of a succession of designations of the same sign cannot prevent the recognition of the presence of a fading procedure.

Abstract: For filter video signals a median selector is used to the inputs of which the sample values of a first pixel and other neighboring pixels. These other pixels lie in the line direction (horizontal) and in a direction perpendicular thereto (vertical) next to the first pixel. The filtering is improved if at least one additional pixel is provided in each of those directions, providing a cruciform filter window. A still further improvement is provided if pixels which immediately preceed or follow the first pixel in the time-dimension (i.e. pixel values from a previous or following picture) are also supplied to the median selector. By utilizing interpolated sub-pixels close to the central or first pixel, disturbances, not only from noise or drop-out, but also from chrominance cross-talk, can be mitigated or avoided.

Abstract: A digital oscillator clocked by clock pulses (T) produces an output rectangular wave, the phase of which is controlled by a magnitude supplied to a D register (8'). The most significant bits of that magnitude are derived from the contents of a counter (4) clocked by the output signal (S), while some less significant bits of that magnitude, representing the progression of equal fractions of the period of the output wave are generated by a combination of the undelayed output wave and at least one delayed output wave which combination is stored at intervals of the reference frequency to which the oscillator is locked. That stored combination is converted from a Gray code to a binary code for compatibility with the counter state. The converted additional bits also control a multiplexer which selects the correspondingly delayed reference frequency signal for clocking a D register (15) which is loaded with the counter content and the converted additional bits.