if you do neglible amounts of manipulation, then 8-bit versus 16-bit isn't worth worrying about. if you need to make some adjustments, especially in the shadow areas, 16-bit mode gives you a lot more freedom to make them without getting banding from overmaniplation. bringing up the shadows a lot using the Photoshop CS Shadow/Highlight tool will really make it obvious. this is what i have been referring to as posterization in the past.
the effect of using 4X sampling is harder to see but it reduces the amount of noise in the image. this will be most apparent in areas of near constant tone and in shadows if you bring up the levels to show more detail. try a bringing up the shadow detail on a few dense Velvia slides and you will see. the rule of thumb is that every doubling of sampling is equivalent to adding another bit to the signal to noise ratio. thus 4X is about the same as scanning in 16-bit mode on the Nikon and then cutting off the lower two bits to yield the 14-bit result returned by the scanner hardware. this of course gets translated into 16-bits per channel by the time it reaches Photoshop. the least significant two bits are constant across the image. Herb... ----- Original Message ----- From: "Kenneth Waller" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, March 31, 2004 9:43 PM Subject: Re: OT Scanning images (was Different films, different results) > Herb, what are the differences you have observed with the 14 bit scanning > and the 4X oversampling? > I was just pondering the 16 bit issue today and haven't come up with > anything yet.
