1. An image processing apparatus comprising: an acquisition unit that acquires an image having object regions; a detector that detects each object region from the image acquired by said acquisition unit; a luminance distribution calculator that calculates a plurality of luminance distribution information for respective object regions detected by said detector; a representative luminance value calculator that calculates a plurality of representative luminance values for respective object regions detected by said detector; and a determination unit that determines tone characteristics, which are used for tone compression, for respective object regions, wherein said determination unit determines the tone characteristic for a target object region based on a luminance distribution of the target object region and a difference between the representative luminance value of the target object region and the representative luminance value other than the target object region.