`Pencigraphy´ with AGC: joint parameter estimation in both domain and range of functions in same orbit of the projective-Wyckoff group

Consider a static scene and fixed center of projection, about which a camera is free to zoom, pan, tilt, and rotate about its optical axis. With an ideal camera, the resulting images are in the same orbit of the projective group-action, and each pixel of each image provides a measurement of a ray of light passing through a common point-in space. Unfortunately, most modern cameras have a built in automatic gain control (AGC), automatic shutter, or auto-iris, which, in many cases cannot be turned off. Many modern digitizers to which cameras are connected have their own AGC which also cannot be disabled. With AGC, the characteristic response function of the camera varies, making it impossible to accurately describe one image as a projective coordinate transformed version of another. This paper proposes not only a solution to this problem, but a means of turning AGC into an asset, so that even in cases where AGC could be disabled, pencigraphers of the future will be turning AGC on