1. An image processing apparatus comprising: an image processing unit generating a pixel value of an output image by carrying out a pixel value blending process on a long exposure image and a short exposure image, wherein the image processing unit includes: an exposure compensation unit carrying out exposure compensation of the long exposure image and the short exposure image in keeping with an exposure ratio between long exposure and short exposure; a blur information measuring unit using the long exposure image and the short exposure image after the exposure compensation to calculate blur information that is an index value showing a degree of discrepancy between pixel values at a corresponding pixel position in the long exposure image and the short exposure image; a blending coefficient calculating unit using the blur information to decide a blending coefficient as a blending ratio to be used in the pixel value blending process on the pixel values at the corresponding pixel position in the long exposure image and the short exposure image; and a blending unit carrying out the pixel value blending process on the pixel values at the corresponding pixel position in the long exposure image and the short exposure image using the blending coefficient calculated by the blending coefficient calculating unit to decide the pixel value of the output image.