Ever wondered how NASA and hobbyists can produce such stunning images of the night sky? A key element in producing visually compelling images is applying a nonlinear system to the image data collected by both amateur and professional imaging equipment. This is known as "stretching" the image and has the effect of exaggerating differences between relatively low light objects while compressing the differences between high intensity objects. Often nonlinear effects are avoided in signal processing; however, this is one application where nonlinear processing is essential. Read about it at Nonlinear Systems: An Important Tool for Astrophotography.
