David, I am not an engineer so I could very well be using terms that have techincally precise meanings in imprecise commonsense everyday fashions. By "raw data," I only meant to designate the original data captured by the scan prior to any compression; and thus, I was only trying to say that if one is using lossy compression processes even at their minimum levle of compression there must in principle be some loss of information so there theoretically in principle must be more detail in the pre-compression data than in the post compression data even if it is of no practical significance. After some posts by Anthony, it has become clear that he was talking in "for all practical purposes" terms much like you are and with which I agree.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of David J. Littleboy Sent: Sunday, June 09, 2002 8:10 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: JPG sharpening [was: Color spaces for different purposes] "Laurie Solomon" <[EMAIL PROTECTED]> asked: >>>>>>>>>>>>>> >Scans do not contain more detail than a low-compression JPEG can >hold. This statement I do not understand; please elaborate. Surely, this cannot be the case if we are talking about raw data as opposed to encoded compressed data even at the lowest setting in which there still is some compression of the raw data. <<<<<<<<<<<<<< The raw data is not truly random data. It is actually smoothly changing nearly continuous data. So there is a lot of room for lossless compression. Low-compression JPEG is very close to lossless compression, and only loses information in areas of high detail and contrast. Since raw scan data doesn't have such areas, JPEG works well. David J. Littleboy [EMAIL PROTECTED] Tokyo, Japan ---------------------------------------------------------------------------- ------------ Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
