Rob, Both, slides and prints have their advantages. Lattitude is only one half of the equation. Dynamical range is the second half. No, you cannot "create" either one in Photoshop. No matter what you do there, you will only lose data.
Consider an absurd example: you have only 2 bits for 1 (greyscale) color. Your color values are 0, 1, 2, 3 A given image on "slide" media (narrow lattitude, high contrast) may have distribution curve like 5% 40% 40% 5% 0 1 2 3 (kinda like reduced bell-curve ). Probably, some shadows and some highlights will be lost (e.g. 0 is really black black, no detail there) -- I made the numbers add up to 90% intentionally :) A given image on "print" media (high lattitude) will squeeze all the pixels into middle greys: 0% 50% 50% 0% 0 1 2 3 See what's wrong here? You have no "shadows" lost except for the fact that you don't have 4 colors anymore! You trade lattitude for contrast and vice versa. Unless there is a film whose lattitude and dynamic range match those of a scanner perfectly, there's no "better" or "worse" between slide and print films. Just a matter of preference. E.g. on overcast day, when the lattitude is largely irrelevant, I think slides will be superior, in terms of amount information they carry from the original scene to the computer file. For a very high contrast scene, print film wins. Best, Mishka. ----- Original Message ----- From: "Rob Studdert" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, August 29, 2002 6:56 PM Subject: Re: Sanning negs vs positive tranparinces > On 29 Aug 2002 at 15:05, Herb Chong wrote: > > > negatives have less brightness range than slides. you will still get best > > results from scanning slides if you have a good enough scanner. > > Why do you believe this? Scanning negs gives a far superior contrast range, you > can never get beyond a little over 4 stops from a slide. I think that you will > find of many top end professionals in landscape (not 35mm format) who are more > clever than to believe that Velvia is the only true film have switched to > quality negative films for using in their film to digital work-flow. These > people don't have to pacify idiot editors who reject any image that they cant > view on a light-box. > > Cheers, > > Rob Studdert > HURSTVILLE AUSTRALIA > Tel +61-2-9554-4110 > UTC(GMT) +10 Hours > [EMAIL PROTECTED] > http://members.ozemail.com.au/~distudio/publications.html > >
