To provide an image signal processor and processing method in which IP conversion can be carried out accurately using a small memory capacity.

Movement is detected using the data of current field and the data of one frame delay by determining a function representative of a movement due to the absolute value of difference between two data. Values V1 obtained from the data of pixels C and D of the lines before and after a pixel R for detecting the movement by in-field interpolation using a function representative of a predetermined movement of a pixel B at the same position as the current field are stored for three lines and a minimum value is determined. Subsequently, a maximum value among the minimum values of adjacent pixels obtained similarly is determined and stored for three lines and the maximum value thereof is determined. Furthermore, a maximum value is determined for adjacent pixels by similar processing and employed as a movement.