Variations in task and the ideal observer

previous studies involving the ideal observer, the task considered has been that detection where it is assumed that there is complete a priori knowledge of the and of the possible object's shape, amplitude, and position. It is shown that the detection task to include the possibility of an unknown, slowly varying back._ _ ground reduces the importance of the low-frequency components in the image for the ideal observer. More complicated tasks than object detection are also considered, such as determination of an object's position and width and the resolution of two objects. These higherorder tasks further enhance the importance of the high-frequency information content of the image.