TS: you might want to have a look at this, posted just a some days ago: http://www.clubsnap.com/forums/showthread.php?t=650599
Let's put aside the mediocre presentation skills, jump to 14:45min - it shows the theory of "How does the Big World fit into the small media" - Big World referring to the big dynamic range of the world outside, compared to the much smaller dynamic range of any media (sensor, film, print). As you can see, the process requires selective actions, depending on the input signals. Some parts of the original input need to be compressed, others need to be expanded. Please elaborate how this selective processing of an image can be achieved by using a passive filter with uniform transmission characteristics across the entire frame and throughout the entire light spectrum we use. (Let's put aside any colour casts here.)