[EMAIL PROTECTED] mused: > > In a message dated 3/12/2005 10:50:23 PM Pacific Standard Time, > [EMAIL PROTECTED] writes: > That's a true lossless compression scheme. Now imagine that one of > those 100 pixels is almost, but not quite, the same colour. That's > going to need more space to describe. Still not as much as storing > all the original values, but more that the compressed version. > If you ignore that different pixel, and pretend it's the same colour > as the other 99, you don't need to use the extra space. In other > words you've given up a small amount of the original data in trade > for an even smaller file. > ======== > One more question (for now until I am more up to speed), John, Godfrey, > anyone -- doesn't this raise a question about an increase in megapixels for > the > same size sensor (for instance, same sensor used for 6mp as 8mp)? In other > words, > couldn't there be more information lost once one increases the number of > megapixels? Even though they are trying to do lossless compression with RAW > files? > > And how about larger sensors with more megapixels (from what I've heard > though that may not be a problem, though, since the RAW files are > correspondingly > larger). > > Same sensor more megapixels, I would think one might enter the realm of not > having truly lossless compression in a RAW file. > > Right or wrong?
Wrong. You can't use the same sensor for 6mp as for 8mp; the number of megapixels is a physical property of the circuitry constructed on the sensor. (But you can have an 8mp sensor that's the same *size* as a 6mp sensor) The RAW file stores pixels, so the size depends on the number of megapixels.
