According to an embodiment, an image processing apparatus includes an obtainer, a setter, a first calculator, a second calculator, and a third calculator. The obtainer obtains an image. The setter sets a plurality of first regions and a plurality of second regions on the image. Each of the first regions and the second regions includes two or more pixels, and at least one of the second regions is different in position or size from the first regions. The first calculator calculates first feature data representing an image feature of the first regions. The second calculator calculates second feature data which is a luminance gradient between the second regions. The third calculator calculates relative feature data representing a relative relationship between the first feature data and the second feature data.