To prevent the generation of a part having both high sharpness and noise level and a part having both low sharpness and noise level and to prevent a picture quantity from being lowered by a moire phenomenon even when an interpolating point is close to a sampling point by almost fixing the square sum of interpolation coefficients at all the time regardless of a coordinate value.

On the basis of three sampling data in data streams sampled at spatial and timewise equal intervals, an image processing part 70 performs interpolating calculation for estimating data at any arbitrary point. The sum of the respective data and the interpolation coefficient to be used for product- sum operation is almost fixed to '1', the product-sum with respective sampling coordinate values is almost equal with the coordinate value of the point to estimate and the square sum of the interpolation coefficients is almost fixed at all the time regardless of this coordinate value. Even when the interpolating point is close to the sampling point, by introducing surrounding sampling values to the interpolating calculation in a prescribed ratio, smoothing operation equal with the intermediate point can be applied.