Tone-conversion device for image, program, electronic camera, and tone-conversion method

摘要

The present invention relates to a tone-conversion device for converting a tone of an image having an achromatic signal and a chromatic signal, and it includes the following components: a signal extracting unit defining an achromatic signal of a first pixel or a second pixel from plural pixels as an achromatic signal value, the second pixel being in an immediate neighborhood; a neighborhood processing unit generating a local signal of the first pixel according to the achromatic signal and the chromatic signal of a third pixel contained in the neighborhood area which is larger than the second pixel; a gain determining unit determining a conversion gain for the first pixel according to the achromatic signal value and the local signal; and a tone conversion unit performing tone conversion by multiplying the signal component of the first pixel by the conversion gain.