Abstract
Describes a system using two complementary storage tube subtraction schemes in series. The first storage device, operated in a moving target indicator mode, is used to take the difference between opposite phases of a time-dependent video signal and writes it on a second storage tube. The input device then takes the difference between two equal input signals and subtracts this from the image on the second tube. In this way problems associated with the limited dynamic range subtraction properties of the second tube are reduced. With this method signals have been brought a fraction of 1% to full contrast. The sensitivity of this technique was compared to that required for dual energy X-ray absorption edge imaging.