Can anyone explain please

[Balky]

I am new to Photshop...

Please tell me what do you achieve but converting from 8 to 16 bit. I know how just don't know WHY and WHEN.

THanks much

[Doug Nelson]

See if this link helps.

[jeaniesa]

Welcome to RetouchPro, Balky!

The link that Doug pointed you to has quite a bit of info, but please don't be shy about asking more questions if you still have some after reading it (or if more pop up because of reading it. )

Jeanie

[Balky]

SCANNER

I have a Microtek Scanmaker 4700

It does not provide the option 16 bit for RGB images but b&w only.

However, it has the option of 48 bit RGB along with Plain RGB Color. BUT isn't it redundant to scan in 48 bit if the scanner is only 42-bit scanner?

I think it would just boost up the file size.

eh?

Thank you all guys for your replies :-)

[Doug Nelson]

It can be confusing, but anything above 8bits per color channel is treated in software as 16bits per channel, even if it isn't 16bit. So, a combined 42bits is still treated as 48bits. I told you it was confusing

Everything said about full 48bits still goes, just not quite as much.

[Stephen M]

http://members.ozemail.com.au/~binaryfx/PSTV_links.html#H

In short 8>16 will still only give you a true 8 bpc of data (and there is probably less due to image noise) - but it will open up more levels for digital processing, before you reduce back to 8 bpc for output.

However, scanning in 10-16 bpc will give you more data and it is very quick to use the scanners high bits and there should be no reason not to - but whether you choose to work in higher bits after the scan/capture is another story, some devices only give you 8 bpc from the internal high bits, while others can supply Photoshop the high bits too.

People who feel strongly about their archival data often love high bits, while those who feel strongly about their bottom line time/profits see no need for the more limiting workflows and higher file sizes since common print output does not seem indicate this extra quality, and most clients care more about the output than the data, so it is hard to bill them for the better 'data' (your time spent in high bit) when the output does not show this.

The links listed above at my sites links page should give you a lot of info about high bit workflows - from all points of view.

Regards,

Stephen Marsh.