Imaging methods that ensure positive images

摘要

We discuss methods of image reconstruction which lead to non-negative images: no negative values appear in the estimate or approximation to the unknown object. We describe methods which always lead to non-negative estimates of the object, characterize some regularized and non-regularized methods, and characterize those orthonormal systems whose partial series approximations to the object are always non- negative. This paper surveys the authors' recent research, adds some new results, and discusses related work.