Abstract: There is disclosed herein an apparatus and method for accurately ascertaining the time of occurrence of passage of the leading and trailing edges of an input pulse through the 50% amplitude level. The apparatus implements the transfer function 1 - cos(wt) where t is equal to the round trip delay through a delay line, and w is the angular velocity of each fourier component of the input signal. In one embodiment, a summing resistor and a delay line having a characteristic impedance equal to that of the resistor are used. The output of the delay line is coupled to one input of a comparator, and the other input is coupled to the junction between the summing resistor and the delay line. Another embodiment uses two matched delay lines, two factoring circuits, a summing circuit and a comparator to implement the same transfer function.

Abstract: Non-orthogonality of the blanking region information caused by the 25 Hz offset in a digital PAL-encoded color television signal is corrected by a dynamic offset circuit. To this end, a plurality of waveforms describing the envelopes of the blanking, sync and burst are stored, and during video signal processing are sequentially addressed at a 25 Hz rate. The resulting assembled output blanking information is orthogonal to the television scanning frequency.

Abstract: A gray scale test chart for television cameras, in the form of either a transmittance chart or reflectance chart, includes one or more regions having selected gray values for calibrating or adjusting the output signal of the television camera, each gray value region being formed by an array of uniformly black dots arranged on a uniformly white background in a spatial frequency selected with respect to the resolution capability of the camera to produce an integrated output signal while being within the resolution capability of a photographic or other chart reproduction technique, the size of the dots in each region determining its gray value in combination with the spatial frequency or center-to-center spacing of the dots.

Abstract: Apparatus is disclosed for providing error compensation of a video information signal having a PAL format. Sampling of the analog PAL format video information signal is done at a rate of four times the chrominance subcarrier frequency and is done in a precise manner whereby the samples are taken along orthogonal vector axes that are oriented at 45.degree. relative to the U and V vector axis. When samples are taken at the prescribed locations, substitute samples in the form of multi-bit digital words can be used as replacements for defective or missing sample words, which replacement samples exhibit the same vector phase as the defective sample, but which are taken from either the preceding or succeeding line relative to the line in which the defective sample is located. The apparatus of the present invention obviates the necessity of performing any arithmetic computation to derive the value for the sample to be substituted. Moreover, the sample is spatially closely related to the defective sample, i.e.

Abstract: A digital chrominance signal in a digital component television system is digitally filtered to obtain sampling values intermediate the sampled values obtained during analog to digital conversion of the chrominance signal, such that the resultant number of chrominance samples per second in the digitized chrominance signal corresponds with the number of luminance samples per second in the digitized luminance signal. The samples values of the digitized chrominance signal including the computed intermediate values may also be modified by said digitized filter to minimize the alias created by the analog to digital correction sampling process, to compensate this signal for sine x/x losses existing in the digitized chrominance signal, to compensate for Gaussian filter attenuation of the chrominance signal prior to analog to digital conversion thereof, and to compensate for other deficiencies in the chrominance signal.

Abstract: A wideband chroma key switching signal is generated from lower bandwidth chrominance signals in a video signal by first conventionally generating a chroma key switching signal from these chrominance signals, and then detecting high frequency transition components in the corresponding luminance signal. These luminance signal high frequency components are then added to the switching signal in a manner that insures that their polarities match, thereby generating a higher bandwidth chroma key switching signal. This resultant higher bandwidth chroma key switching signal is used to control cross fade amplifiers which function to output either the video signals of a first or a second scene with linear transitions between these video signals during switching.

Abstract: A total raster error measurement and correction circuitry, using digital memory means in the camera head for the storage of correction data, corrects spatial scan, shading, etc., errors in a television picture in two dimensions. The basic spatial error correction circuit effectively synthesizes horizontal rate waveforms on a number of discrete lines of the vertical scan. On all scanned lines between discrete lines, a linear approximation between the two discrete waveforms is made to form a vertically continuous waveform. Black and white shading errors are measured by comparing the black and white video levels against respective selected black and white D.C. levels with and without a cap on the camera lens. Gamma correction is provided by comparing the peak black and white levels to derive any gray level errors.