1. An image signal processor, comprising: an image signal frequency zone limiter that limits a frequency zone of an input image signal; an image signal frequency zone enhancer that enhances a frequency zone of an input image signal; an edge character detector that detects an edge of a character of an input image signal; and a gain controller that controls and outputs output pixel signals from the image signal frequency zone limiter and the image signal frequency zone enhancer according to the output of the edge character detector; wherein the gain controller changes a ratio in intensity of output image signals from the image signal frequency zone limiter and the image signal frequency zone enhancer according to an output result of the edge character detector and executes an adding process.