A picture processing apparatus for processing picture signals of different formats. A memory stores input picture signals. A read-out section reads the picture signals stored in the memory in terms of a preset number of the picture signals as a unit. An interpolation section interpolates picture signals for a preset position by executing preset calculations on the plural picture signals read out. For picture signals of an HD format, the picture signals are simultaneously read out in terms of the four pixels as a unit to execute four-point interpolation processing. Whilst for picture signals of an SD format, after a conversion to a 960.times.720 frame picture by applying field/frame conversion and doubling the number of the pixels in the vertical direction, the picture signals are stored in the memory. The operating frequency and the number of times of operations of the read-out section and the interpolation section are changed to values as large as four times those. Thus, the picture signals of the SD format are simultaneously read out four times in terms of the four pixels as a unit to execute the 16-point interpolation processing.