Abstract: An image signal processing device includes a logarithmic compression circuit, filtering circuit, filtering characteristic setting circuit and dynamic range/gain control circuit. The logarithmic compression circuit subjects an input image signal containing a color signal to the logarithmic compression. The filtering circuit serves to filter the input image signal. The filtering characteristic setting circuit adaptively sets the band pass characteristic of the filtering circuit according to the feature of the input image signal. The dynamic range/gain control circuit controls the dynamic range and gain of the filtered input image signal.

Abstract: A device for determining a control signal for an image observation system including an image intensifier and an image converter wherein the control signal is representative of the contrast range of an output signal of the image converter and with control elements for adjusting the gain of the image intensifier and the gain of the image converter in a manner whereby the control signal at a value representative of a large contrast range in the output of signal of the converter results in higher adjustment gain of the image intensifier and a lower adjustment gain to the image converter and where the control signal at a value representative of a low contrast range in the output signal of the image converter results in lower adjustment gain to the image intensifier and higher adjustment gain to the image converter.

Abstract: A signal processing system is disclosed in which the image resolution is improved by extending the horizontal frequency bands of separated luminance and chrominance signals and compensating the contour of an input image signal, the frequency band of the input chrominance signal is extended by the chrominance signal processing part, and by the extension of frequency band, the transition time of the high frequency components of the image signal is reduced for the high frequency image signal processing and reducing the short data processing time.

Abstract: The present invention provides a contrast control circuit capable of controlling the contrast even if the back porch is comparatively short. The contrast control circuit comprises monostable multivibrators (24, 26) which provides a background pulse and a reference pulse alternately, respectively, a switch (SW1) which clamps a video signal while the background pulse is HIGH so that the potential of the pedestal level is zero on an (N+1)th horizontal scanning line, and a switch (SW2) samples the leading edge of a reference pulse inserted in the video signal while the reference pulse is HIGH on an nth horizontal scanning line.

Abstract: A horizontal edge compensation circuit includes a delay circuit for delaying an input luminance signal for a certain time, a waveform converter for differentiating the input luminance signal to take its absolute value, and reshaping the waveform of the signal, a quantization circuit for differentiating again the first differentiated signal, comparing to predetermined reference levels the first differentiated signal obtained by emphasizing a signal having a low level difference and bypassing a signal having a high level difference, and then generating a code signal to quantize the second differentiated signal, a gain controller for selectively multiplying the reshaped signal according to the code signal, and controlling the degree of horizontal edge compensation, and an adder for adding the luminance signal delayed for a certain time in the delay circuit to the horizontal edge compensation signal output from the gain control portion.

Abstract: A circuit arrangement for automatic gain control of NRZ data signals. In this arrangement there is detected with the aid of two comparators whether a logic level in the NRZ data signal produced by a controllable amplifier is exceeded or fallen short of. The signals produced by the comparators are time-averaged with the aid of RC combinations and subjected to a logic AND combination. The signal available at the output of the AND combination is integrated in an integrator stage and transported as a control signal to a set input of the controllable amplifier.

Abstract: An amplitude control device for controlling an amplitude of a data signal having an reference amplitude includes an A/D converter which converts the data signal to an n-bit digital signal, an extraction circuit for extracting the reference amplitude from the n-bit digital signal, a compactor for comparing the extracted reference amplitude with a predetermined amplitude to produce a first signal when the extracted reference amplitude is greater than the predetermined amplitude, and a second signal when the extracted reference amplitude is smaller than the predetermined amplitude. A counter counts up and down on receipt of the first signal and second signal, respectively, and produces an m-bit digital signal representing the counting result. A ROM stores a table in which the n-bit digital signal and the m-bit digital signal are used as an address for designating a value equal to the n-bit digital signal multiplied by a coefficient determined by the m-bit digital signal.

Abstract: Disclosed is an automatic contrast correction method and apparatus for optimizing contrast of a picture screen. There is included an effective picture screen extractor for extracting video data corresponding to the effective picture screen among video data in the picture screen, a plurality of amplifiers for receiving the video data and amplifying the received video data for output, and a microcomputer for comparing the average value which is calculated from the video data of the effective picture screen with a previously set reference value and regulating an amplification factor by supplying a control signal to the amplifiers according to the comparison result. Even if video images photographed toward the sun are printed, it can be prevented from being printed in a dark state, thereby obtaining a good quality of picture.

Abstract: A process for the automatic contrast and brightness control for thermal imaging apparatus of FLIR systems which is used for forming the actual value of the contrast and brightness of an evaluation window, fixing the shape of the evaluation window and displacing the position of the evaluation window in dependence on the content of the FLIR image, includes: utilizing "n" vertical image columns for evaluation of the FLIR image, converting the average brightness of the FLIR image into an analog voltage signal, comparing the analog voltage signal with a video signal of the FLIR image, summing the results of the comparison in the vertical image columns of the FLIR image such that a sum value results for each image column, determining the position of the horizon from the amounts of the sum values, and in the case of column sums that differ from each other, determining the optimum position of the evaluation window in the horizontal direction from the sum values of the columns such that the surface center of gravity o