1. An image-processing apparatus for converting a first image data inputted into said image-processing apparatus to a second image data used in a visible-image outputting apparatus, which forms an image so as to make it visible for a human eyesight based on said second image data, said image-processing apparatus comprising: a data-characteristics acquiring section to acquire data-characteristics of said first image data, including at least one of a dynamic range and a frequency characteristic, by analyzing said first image data inputted into said image-processing apparatus; a memory section to store apparatus-characteristics of said visible-image outputting apparatus; and a processing section to adaptively change a data-converting method for converting said first image data to said second image data, corresponding to said data-characteristics of said first image data acquired by said data-characteristics acquiring section and said apparatus-characteristics of said visible-image outputting apparatus, stored in said memory section.