1. An image processing device for converting an input image into an output image whose blur is reduced, said image processing device comprising: a first image extracting section configured to extract a plurality of pixels composed of a pixel of said input image which corresponds to a pixel of interest within said output image and predetermined pixels surrounding the pixel of interest; a first feature quantity calculating section configured to calculate a first feature quantity from said plurality of pixels extracted by said first image extracting section, the first feature quantity being a difference between two autocorrelation values based on a superposition of a first block of pixels and a second block of pixels, the center of the second block of pixels being distant by a predetermined number of pixels from the center of the first block of pixels, the first block of pixels including the pixel of interest; a processing coefficient generating section configured to obtain a second processing coefficient based on said first feature quantity and a first processing coefficient, said second processing coefficient being generated by operation on said first feature quantity and said first processing coefficient, the first processing coefficient being learned in advance from a normal equation based on a relational equation for generating an unblurred teacher image based on the second processing coefficient and blurred images to which blurs of a plurality of kinds of amounts of blurring are added as student images; a second pixel extracting section configured to extract the pixel of interest and a plurality of pixels surrounding said pixel of interest from said input image; a predicting section configured to generate a pixel value of said pixel of interest based on said plurality of pixels extracted by said second pixel extracting means and said second processing coefficient; a nonlinear feature quantity determining section configured to determine a nonlinear feature quantity as said first feature quantity using a second feature quantity of each of a plurality of kinds of blur removal result images, the plurality of kinds of blur removal result images being based on said student images.