An image processing device comprising: producing means for producing a first image having a first resolution and a second image having a same content as the first image at a second resolution lower than the first resolution, based on an input image; luminance outputting means for sequentially outputting luminances of pixels constituting the first and second images based on an order of pixels; gradient direction outputting means for sequentially outputting gradient directions of luminances of the respective pixels of the first and second images in parallel by using the sequentially output luminances; a timing controller for controlling timings to supply pieces of gradient directions of luminances of the first and second images to a co-occurrence matrix preparing means for preparing a co-occurrence matrix including co-occurrences of the gradient directions occurring in the both the first and second images by sequentially combining the sequentially output gradient directions for each of the first and second images; and co-occurrence matrix outputting means (30a, 30b, 30c) for outputting the prepared co-occurrence matrix as an image feature amount of the input image, wherein the gradient direction outputting means comprises: a first resolution-specific gradient direction outputting means that outputs gradient directions of luminances of the pixels of the first image at the first resolution; and a second resolution-specific gradient direction outputting means parallel to the first resolution-specific gradient direction outputting means, the second resolution-specific gradient direction outputting means outputting gradient directions of luminances of the pixels of the second image at the second resolution; and the first and second resolution-specific gradient direction outputting means are concurrently operated to sequentially output the gradient directions for each of the first and second images in parallel. producing means for producing a first image having a first resolution and a second image having a same content as the first image at a second resolution lower than the first resolution, based on an input image; luminance outputting means for sequentially outputting luminances of pixels constituting the first and second images based on an order of pixels; gradient direction outputting means for sequentially outputting gradient directions of luminances of the respective pixels of the first and second images in parallel by using the sequentially output luminances; a timing controller for controlling timings to supply pieces of gradient directions of luminances of the first and second images to a co-occurrence matrix preparing means for preparing a co-occurrence matrix including co-occurrences of the gradient directions occurring in the both the first and second images by sequentially combining the sequentially output gradient directions for each of the first and second images; and co-occurrence matrix outputting means (30a, 30b, 30c) for outputting the prepared co-occurrence matrix as an image feature amount of the input image, wherein the gradient direction outputting means comprises: a first resolution-specific gradient direction outputting means that outputs gradient directions of luminances of the pixels of the first image at the first resolution; and a second resolution-specific gradient direction outputting means parallel to the first resolution-specific gradient direction outputting means, the second resolution-specific gradient direction outputting means outputting gradient directions of luminances of the pixels of the second image at the second resolution; and the first and second resolution-specific gradient direction outputting means are concurrently operated to sequentially output the gradient directions for each of the first and second images in parallel. a first resolution-specific gradient direction outputting means that outputs gradient directions of luminances of the pixels of the first image at the first resolution; and a second resolution-specific gradient direction outputting means parallel to the first resolution-specific gradient direction outputting means, the second resolution-specific gradient direction outputting means outputting gradient directions of luminances of the pixels of the second image at the second resolution; and the first and second resolution-specific gradient direction outputting means are concurrently operated to sequentially output the gradient directions for each of the first and second images in parallel.