Jawed wrote: > I would agree with this. The intention is quite > clearly to make the data fill the range of possible > values. For reasons analogous to the use of 16-bit > scans (really 10, 12 or 14 bits, generally): to > maximise tonal smoothness and provide resilience > under further editing.
Maybe I'm misreading this, but something I've wondered is whether any scanners actually remap the data. It's hard to describe without a diagram - suppose you have a monochrome scanner with an 8 bit A/D. The A/D can only produce numbers from 0 to 255. If the actual image information is all between (say) 10 and 245 then you've effectively lost 8% of the resolution possible from 8 bits. But if you remap that range so that 10->0 and 245->255, you're "stretching" the values in between. I presume this "stretching" is what adjusting levels actually does. But presumably the fewer bits from the A/D, and the smaller the input range, the poorer the result would be. Does setting the black and white points cause the data to be remapped? I presume this remapping is always post A/D. Are there any scanners which attempt to adjust the input levels to maximise the range of values from the A/D? As far as I can tell, setting the black and white points in (say) Nikonscan is no different to doing the same thing to a "flat" file in Photoshop with Levels? BTW as far as colour shifts are concerned, I found Picture Window Pro's ability to do levels in colour spaces other than RGB helped a lot. RGB levels in PS tends to shift the colour balance, but HSL levels in PWP doesn't. What am I missing here? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
