To make clear the positional relation of an extracted area with a picked-up image by extracting a pixel from the picked-up image with a color component as a feature amount and next displaying the pixel which is not to be extracted in achromatic color or with chromaticity different from that of the pixel to be extracted.

A memory stores a combination of display colors in respective three areas which are divided into a pixel area outside of a window frame 20, pixel area to be an extraction object inside the window frame 20, and pixel area to be a non-extracted object inside the window frame 20. Then, the color of that area outside the window frame 20 and the extracted area inside the window frame 20 is made equal to the color to be displayed in a source image 2 and the non-extraction area inside the window frame 20 is made into monochromatic achromatic color. Based on such display information, a CPU outputs an image to an image output part so as to display it on a screen. Thus, the positional relation of the extracted area with the picked-up image can be made clear.