What is state of the art in denoising images with high PSNR?

Hello,

by writing a report (tools) about denoising video in realtime  I want to
know what were the latest cognitions in denoising
images  with higher signal-to-noise ratio.

I am focussed on techniques of spatial filtering (time based will be
ignored, because latency).

I found various papers, pE. from Peters II/Alan (A New Algorithm for
Image Noise Reduction using Mathematical Morphology,1995), Donoho (
De-noising by soft-thresholding, 1995), Hsia/Chan (A FAST EFFICIENT
RESTORATION ALGORITHM FOR HIGH-NOISE-RATIO IMAGE USING FEATURE ADAPTIVE
APPROACH, 2002) and I analyzed the stuff around transcode-/virtualdub
filters.

IMHO the most popular methods were open/closing and weighted mean/median
based
filtering. I am right? What were also important papers and/or
technologies to handle with noisy images without access to the original 
image? What is the state of the art in denoising generally?

Which criteria is most helpful to build an ergonomic, clean image (from
the humans eye view) from a highly noised one?

Which methods have a good balance between quality and calctime
consumption, which were realtime operable?

Could anyone explain me the mode-filter (it could be a ranking-filter)

Thanks,

Bye Andreas
--