Image processing device, image processing method, and image processing circuit

An image processing device configured to synthesize a first image and a second image shot in two or more exposure times different in length in a parallel way within one frame time, includes: a level adjuster configured to adjust the first image and output a corrected first image having a luminance level substantially aligned with a luminance level of the second image; a movement detector configured to calculate absolute values of differences between positionally corresponding pixel pairs in the corrected first image and the second image and accumulate the calculated absolute value on an image block basis to obtain a movement detection amount on the image block basis; a movement blending ratio calculator configured to smoothen the amounts of detected movement and calculate a movement blending ratio between positionally corresponding pixel pairs based on the smoothened amounts of detected movement; and an image synthesizer configured to generate a movement-adaptive image by synthesizing pixels at the corresponding positions at the movement blending ratio.