Abstract: A network combines luminance and chrominance signals to provide a composite video signal wherein the chrominance signal is subjected to band pass filtering to reject low frequency noise and the luminance signal is subjected to filtering by a predetermined amount at the color subcarrier frequency to reject color dots. In a preferred implementation, the filter is realized with only one inductor and one capacitor thereby preventing displayed artifacts with the economic and reliability benefits of minimal parts count.

Abstract: Noise estimation circuitry for estimating the noise in a small number of horizontal scanning lines of a video signal includes a lowpass line comb filter responding to said video signal, but not to chrominance-descriptive components thereof. The video signal free from chrominance-descriptive components is repeatedly sampled during the backporch interval of each horizontal scanning line, and the samples are accumulated to generate a revised noise estimate each successive horizontal scanning line.

Abstract: A digital image signal processing circuit for use in a VTR with camera has a signal input terminal to which an image pickup output signal or a video signal is supplied, an analog to digital converter for producing a digital image pickup output signal based on the image pickup output signal or a digital video signal based on the video signal, a digital signal processing portion including first, second and third digital signal processing circuit blocks, a system controller for conducting the change of operation, the change of circuit configuration or the change of circuit coefficient in each of the first, second and third digital signal processing circuit blocks, and signal output terminals from which recording luminance and carrier chrominance signals produced by the digital signal processing portion are derived.

Abstract: A video signal gradation corrector used in a television receiver or the like for preventing the destruction of the gradation of the black side and the floating of the luminance level of the black side and/or an excessive increase of the luminance level of the white side. The corrector can be realized with a small circuit scale. A histogram operating circuit includes an average luminance level detecting circuit. A constant is subtracted from an output signal of the average luminance level detecting circuit by a subtracter. The result of subtraction is multiplied by a constant by a constant-multiplication circuit. A lower-limit limiter circuit limits an output signal of the constant-multiplication circuit to a signal having a value not smaller than 0.

Abstract: A method of correcting digital NTSC color-television signals in transmission error by substituting the error-included digital color-television signals with those digital color-television signals in the corresponding horizontal scanning periods two frame periods before, stored in memory (12), and an apparatus to work the method. When a transmission error is detected in a specific horizontal scanning period, substitute circuit (13) reads from memory (12) the digital color-television signals in the N horizontal scanning periods two frame periods before corresponding to the specific and subsequent N-1 horizontal scanning periods, and transmits the digital color-television signals read from memory (12) in lieu of those digital color-television signals in the specific and subsequent N-1 horizontal scanning periods.

Abstract: In a vertical resolution correcting circuit, a noncorrelation component in a vertical direction of a luminance signal included in a video signal is detected. In a region where it is considered that the detected noncorrelation component consists of vertical changes in the luminance signal itself, emphasis, which increases and decreases with a predetermined characteristic, is put on the level of a reproduced luminance signal. However, when the level of the noncorrelation component is higher than a level equal to the amplitude of a synchronizing pulse or an equalizing pulse of the video signal, emphasis is not put on the level of the reproduced luminance signal so as not to cause malfunction.