Abstract: A contrast enhancement apparatus of a video signal comprises a coefficient generation unit for generating a low frequency mapping coefficient which increases or attenuates the low frequency component of the video signal, a minimum value processing unit for detecting the minimum value of the video signal, an edge detection unit for detecting rapid luminance change in the vertical and horizontal direction, a logarithmic conversion unit for converting logarithm by receiving the inputted video signal, a low-pass filter for passing a low frequency component of the logarithm-converted signal, a high-pass filter for passing a high frequency component of the logarithm-converted signal, a first multiplier for multiplying the low frequency mapping coefficient and a signal which passes low-pass filter, a second multiplier for multiplying the signal passes the high-pass filter by the signal outputted from the edge detection unit, a first adder for adding the signals outputted from the first multiplier and the second mult

Abstract: The present invention relates to a contrast enhancing apparatus for a video signal which is capable of enhancing a coefficient characteristic of a light and dark portion of a video signal in a video display apparatus such as TV, etc. In the conventional art, since the attenuating and amplifying coefficients of a low frequency component and a high frequency component are uniformly fixed for enhancing a contrast of a video signal, so that it is impossible to significantly enhancing a contrast of all kinds of videos. In addition, since a transition of a DC level occurs due to an attenuation of the low frequency component, the final output must be scaled again, and the minimum and maximum values of the signal component must be obtained.

Abstract: A contrast enhancement apparatus of a video signal comprises a coefficient generation unit for generating a low frequency mapping coefficient which increases or attenuates the low frequency component of the video signal, a minimum value processing unit for detecting the minimum value of the video signal, an edge detection unit for detecting rapid luminance change in the vertical and horizontal direction, a logarithmic conversion unit for converting logarithm by receiving the inputted video signal, a low-pass filter for passing a low frequency component of the logarithm-converted signal, a high-pass filter for passing a high frequency component of the logarithm-converted signal, a first multiplier for multiplying the low frequency mapping coefficient and a signal which passes low-pass filter, a second multiplier for multiplying the signal passes the high-pass filter by the signal outputted from the edge detection unit, a first adder for adding the signals outputted from the first multiplier and the second mult

Abstract: An apparatus for composing two screens in a television which is capable of solving the problems of a jitter and a screen being cut off at the top and bottom portions caused by a non reference signal in composing two screens, includes a line memory for storing in the unit of lines a video signal for a main screen converted into a digital signal, a frame memory for storing in the unit of frames a video signal for a sub-screen converted into a digital signal, a mixing unit for receiving and mixing the outputs from the line memory and the frame memory to compose two screens, a D/A converter for converting an output from the mixing unit into an analog signal, an encoder for encoding an output from the D/A converter and outputting a double screen signal, a clock signal generator for receiving the horizontal synchronous signals for a main screen and a sub-screen, generating a clock signal corresponding thereto, dividing a horizontal fly back signal in a predetermined number in accordance with a division control sign