Multi-parameter image display with real time interpolation

Abstract

A source (A) of images, such as a CT scanner (10), a magnetic resonance imaging apparatus (12), and the like produces a plurality of basis images (I.sub.0, I.sub.1, I.sub.2, I.sub.3 . . . ). Two of the basis images are subtracted and divided (70, 72) by a number of interpolation increments (L.sub.1) to form a first differential image (I.sub..DELTA.1). The first and the third basis images are subtracted and divided (76, 78) by a number of available interpolation increments (L.sub.2) to form a second differential image (I.sub..DELTA.2). Four differential images are selectively combined and divided by a product of the first and second available increments (82, 84) to form a second order differential image (I.sup.2.sub..DELTA.12). An array of adders (D) selectively adds the first differential image to a currently displayed image stored in an image memory E each time a track ball (104) moves a cursor one increment in a horizontal position. Each time the track ball moves the cursor one increment up or down along the vertical column, the adder array adds or subtracts the second differential image to the currently displayed image. Each time the track ball steps the cursor between rows or between columns, the second order differential image is used to correct one of the first and second differential images. In this manner, only the currently displayed image, the first differential image, the second differential image, and the second order differential image need be stored to provide free interpolation among four basis images. The basis images themselves need not be stored.