  The ultra-high contrast capability required to form images of other solar
systems is arguably the highest-profile challenge in astronomy today. The
current high-contrast imaging efforts all require background subtraction to
separate the planetary image from the image of the host star. Background
estimation is difficult due to the presence of non-common path aberrations
(NCPAs) that change with time. The only major source of information that is not
being utilized by current efforts is the random encoding of the planetary image
and the NCPAs by the atmosphere on millisecond time-scales. Here, a method that
utilizes this information in order to avoid background subtraction altogether
is proposed. This new paradigm will allow simultaneous estimation of the
time-dependent NCPAs and the planetary image via rigorous statistical inference
procedures. These procedures are fully compatible with other information
sources, such as diurnal field rotation and spectral diversity. Given the
open-ended nature of the background subtraction issues, the ideas explained
herein may well the key to imaging habitable planets with Extremely Large
Telescopes (ELTs). Fully exploiting the information content of millisecond
exposures will require significant design modifications of the ELT wavefront
sensors and science camera systems, if ultra-high contrast imaging is to be
priority.
