1. A system for processing image data by adaptively varying pixel resolution within a 2D X-ray medical image, comprising: an imaging detector comprising a matrix array of detection picture elements having a detector pixel resolution for detecting X-rays passed through patient anatomy; an image data processor for adaptively selecting a first area within a 2D image from a plurality of predetermined regular and irregular shaped areas including a shaped area representing an anatomical organ in response to image content characteristics, said first area being allocated a first pixel resolution and adaptively selecting a second pixel resolution lower than said first resolution to be allocated to a second area within said 2D image, and for allocating an anatomical organ shaped first area said first pixel resolution of higher resolution than said second pixel resolution allocated to said second area lying outside said first area and comprising anatomy outside said organ; a combinational processor for combining image data of a plurality of adjacent detection picture elements to provide an individual pixel of said second pixel resolution; and a user interface for generating data representing a 2D X-ray medical image including said first area having said first pixel resolution and said second area having said second pixel resolution lower than said first resolution.