C.H.Ling wrote:
>Absolutely ture, clipped highlights can be saved. JPEG not but RAW yes! You
>can save around 1 stop with Olympus E-1 and C*non 10D file, it is very easy
>check it out yourself. Just download the C1 trial version and play with it.
>
>
>>I don't understand how any software can deal with over
>>exposure. Do you mean it is able to bring back highlights
>>that have been clipped?
>>
It's true. It isn't dealing with overexposure, but with intentional
clipping during processing.
For those who what to know why, it's pretty simple.
First, JPEGs can only be 8 bits for each color or 256 brightness steps.
The sensors can record much more than that, usually 12 or 14 bits in
DSLRs. That means 4,096 or 16,384 possible levels of brightness may be
recorded. What a RAW file does is capture the data as it comes from the
sensor, with all that brightness range intact.
Second, camera manufacturers pretty much have to output JPEGs that have
some zip or pop or whatever you call it when viewed or printed as they
come from the camera. If you read my lengthy post about scanning and
wide latitude, low contrast color neg films and looked at the before and
after examples, you will know that mapping the full range of brightness
captured by the sensor linearly into a JPEG would have a serious
deleterious effect on camera sales. So the manufacturers do a bit of
what film processor/printers have done for ages, they throw away some of
the brightest and darkest data, adjust the midpoint for some contrast
and throw in a bit of curve. Plus they adjust color, but that's not the
point here.
So, using RAW files gets you back to everything the sensor captured and
lets you roll it your way. Depending on how the camera procesor adjusted
the scene and the brand of camera, generally 1 and sometimes almost 2
stops of 'clipped' highlights may be 'recovered' when needed by using
RAW files. "Do You Believe In Magic?"
Moose
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