The present invention relates to an information signal processor and the like preferable for use in the case where a SD signal is converted into a HD signal. A space class and a movement class are detected from the tap pixel data, which is selectively extracted from the SD signal, correspond to a target position in the HD signal. In a memory bank 135, a coefficient seed data in each class and term selection information are stored. In the coefficient production circuit 136, coefficient data Wi in each class is produced according to a production equation containing the term selected by term selection information, using the coefficient seed data in each class and the values of parameters h, v for image adjustment. In a calculation circuit 127, pixel data at the target position in the HD signal is obtained from the prediction tap data xi and the coefficient data Wi, by use of an estimated equation. The compression of the sizes of the coefficient seed data and the calculator is enabled without lowering calculation accuracy, and the approximate accuracy at a coefficient curved surface is also increased.