PURPOSE: To interpolate faithfully a profile of an oblique line by obtaining a brightness alteration signal from an integrating signal of polarity and difference signals and taking an average of sum and product signals between two scan lines.
CONSTITUTION: Scan line signals 1 and 2 are inputted to a terminal 4. After time bases of the signals 1 and 2 are coincided through a delay line 7, they are added to an adder 5, subtractor 17 and multiplier 26. An obtained signal 3 is inputted to a differentiating circuit 24 to obtain a signal 9. By inputting the signal 9 to an LPF 25, a polarity signal 10 can be obtained. A signal 11 and a signal 12 can be obtained by inputting a difference signal 8 to an integrating circuit 19 and by inputting the signal 8 and signal 11 to a subtractor 20, respectively. The circuit is controlled in such a way that the signal 11 and the signal 12 can be outputted when the signal 10 is positive and when said signal 10 is negative, respectively, after the signals 11 and 12 are iuputted to a switch 21. Then, an alteration signal 13 of brightness of a scan line to be interpolated can be obtained. The signals 13 and 14 are inputted to an adder 22 to obtain a sum signal 15, while the signals 15 and 3 are inputted to an adder 23 to obtain a sum signal as an interpolation scan signal.
KIMURA YUICHIRO
OSAWA MICHITAKA
ANDO KUNIO
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