To avoid a blurred picture after magnifying an original image including a line drawing and to reduce a circuit scale for extraction of the line drawing.

This is a frequency converter to apply magnification processing by a multiple of N to an original image corresponding to a desired pixel number. The converter is provided with a line drawing extract means 10 that extracts line drawing from the original image based on a clock signal 1, and with a signal processing means 20 whose output is controlled by the line drawing extractmeans 10, and which outputs based on a clock signal 2 being a multiple of N of the clock signal 1 an image signal obtained by applying a mapping processing to the original image as to the line drawing in the original image as it is, or outputs an image signal resulting of applying an interpolation processing to the original as to the original image other than the line drawing, based on the clock signal 2 or outputs the image signal of the line drawing before the magnification continuously by N times each.