Abstract: An image acquisition apparatus includes an optical system having such distortion aberration characteristics as a central region is expanded and a peripheral region is compressed. An imaging element converts a subject image formed image data. A first memory stores filter factors which are used for interrupting a spatial frequency exceeding a Nyquist frequency of the image data. A second memory stores parameters which define an outer edge of a Nyquist image region. A filter factor setting circuit judges whether each pixel position of the image data is included in the Nyquist image region based on the parameter, and reads the filter factors from the first memory when each pixel position is included. A filter circuit executes filter processing with respect to the image data in accordance with the read filter factors. A distortion correcting circuit corrects the distortion aberration characteristics with respect to the image data.

Abstract: An image acquisition apparatus includes an optical system having such distortion aberration characteristics as a central region is expanded and a peripheral region is compressed. An imaging element converts a subject image formed image data. A first memory stores filter factors which are used for interrupting a spatial frequency exceeding a Nyquist frequency of the image data. A second memory stores parameters which define an outer edge of a Nyquist image region. A filter factor setting circuit judges whether each pixel position of the image data is included in the Nyquist image region based on the parameter, and reads the filter factors from the first memory when each pixel position is included. A filter circuit executes filter processing with respect to the image data in accordance with the read filter factors. A distortion correcting circuit corrects the distortion aberration characteristics with respect to the image data.

Abstract: A variable resistance circuit and application circuits using the same capable of offsetting the variance in the manufacture of integrated circuit and the influence of ambient temperatures, including: a control circuit having a plurality of constant-current output terminals, with a constant current ratio of the output terminals varied by signals applied to a control terminal; an operational amplifier; a resistor; and a plurality of MOS transistors having the gates thereof connected in common; and one output terminal of the control circuit being connected to one end of the resistor and to an inverted input terminal of the operational amplifier and the other output terminal being connected to the drain of one MOS transistor connected at the gate thereof to an output terminal of the operational amplifier and being connected to a non-inverted input terminal of the operational amplifier; and the other end of said resistor and the source of said one MOS transistor being connected to a reference voltage terminal.

Abstract: A variable resistance circuit and application circuits using the same capable of offsetting the variance in the manufacture of integrated circuit and the influence of ambient temperatures, including: a control circuit having a plurality of constant-current output terminals, with a constant current ratio of the output terminals varied by signals applied to a control terminal; an operational amplifier; a resistor; and a plurality of MOS transistors having the gates thereof connected in common; and one output terminal of the control circuit being connected to one end of the resistor and to an inverted input terminal of the operational amplifier and the other output terminal being connected to the drain of one MOS transistor connected at the gate thereof to an output terminal of the operational amplifier and being connected to a non-inverted input terminal of the operational amplifier; and the other end of said resistor and the source of said one MOS transistor being connected to a reference voltage terminal.