I've been thinking more about this 8-bit vs. 16-bit question, and one thing puzzles me and has generally been ignored in this discussion. Someone (Arthur, Austin, Laurie, ????) brought up the question of "noise" in image data, but that issue has been bypassed in these discussions in favor of other comments. Yet it seems noise is the reason high-bit data is superfluous. What I'm thinking:
1. High-bit data is very small compared to low bit data. The ninth-bit is only 0.25% of the value of the full tonal range of 0-100%. 2. All visible files are the product of a final resize/pixel-combination of some sort, at least until we get 2800x4200 or larger video screens. 3. When scanners measure and assign digital values to image elements, adjacent pixels are given discrete values that are generally different by more than 0.25%, that is, the precision of the measurement is less than 8-bits for adjacent pixels. 4. Image editing steps which spread existing pixel ranges over larger ranges do not create more precise intermediate values than the starting value's precision. If an intermediate pixel value must be created between two pixels whose values are 128 and 130 (8-bit), the value won't be more precise if the original values are 127.504 and 129.504 (16-bit). I don't know how typical CCD scanners scan at lower resolutions than their maximum. Whether by averaging pixel values along the CCD array and making larger steps along the film movement, or by some other way, they still end up with adjacent pixel values that differ by more than 1 unit. Knowing these values to .5-unit precision doesn't change the average values reported. For 16-bit processes to be relevant, wouldn't adjacent pixels have to be identical to more than 8-bit precision? Preston Earle [EMAIL PROTECTED] ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
