>>> >> It's been mentioned before, but based on some info Rob Studdert dug up, >> I'm lead to believe that there aren't any extra tricks involved in those >> 22bits. It's probably all about a circuit designed to work with >> different types of sensors, that *for internal use* converts the signal >> from the sensor to a digital value with so many bits that you can be >> pretty sure no information (not even the noise) is lost, no matter what >> sensor you throw at it - and probably also so that calculations that >> involve multiple steps won't loose accuracy between the steps [ ... ] >> > > Somebody mentioned the use of curves to increase the nice parts of the signal > and reduce the noisy part. That could be done with the 22bit conversion, but > this is speculation. I often use curves that way in 16bit TIFF before I > reduce it to 8bit jpeg. > Yes, now that you mention it, the info posted by Rob also suggested that there would be a gamma correction/"curves" stage internally - also working with 22 bits, obviously.
If you do that kind of thing, you'll loose accuracy even in the output data unless you include some extra bits. Basically, these are needed in order to encode the fact that the output from the curves adjustment might fall between two values in the input range, i.e. you may think of the extra bits as representing decimals. Introducing them won't really increase the dynamic range, though, since the adjustment will leave gaps larger than 1 input step at other spots. 22 bits in the final output is probably still pointless, but it has been suggested that you might get 14 or 16. - Toralf -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
