[filmscanners] Re: Help with Vuescan?

["Titus Tucan" <titust@sympatico.ca>]

Dear Arthur I agree with you, if we want to print, or save an image as JPG,
we have to convert it to 8 bit, but there is something I do not understand.
If at the end we convert the image to 8 bit because printing devices cannot
beneficiate from the 16 bit depth what's the use of scanning in 16 bit?
Wouldn't an image scanned with 8 bit colour depth be the same with an image
scanned at16 bit and converted in PS at 8 bit?
Or in other words what are the advantages of scanning in 16 bit?

Thanks a lot

Titus


----- Original Message -----
From: "Arthur Entlich" <artistic-1@shaw.ca>
To: <titust@sympatico.ca>
Sent: Friday, April 05, 2002 4:35 AM
Subject: [filmscanners] Re: Help with Vuescan?


In general, it is suggested that USM or sharpening be the last thing
done on an image (other than perhaps some cloning to fix defects that
appear as a result of the sharpening.)

So, by the time this is to be applied, all the color balancing, level
and curves adjustments, etc, should have been completed in 16 bit.  I
see no advantage to keeping an image in 16 bit mode for printing
purposes.  No printing technique has the color range to make use of 16
bit color depth (I'm assuming you are using an RGB or other color image
with 16 bits per color (48 bit) or is it a monochromic image at 16 bits
total?)

Also, if you are only trying to see if the image benefits from
sharpening, why not convert it to 8 bit within Photoshop, and try
sharpening it?  Save it as a separate image file, which does no damage
to the original 16 bit image.  If it works well, complete whatever other
manipulation you need to for the image in 16 bit mode, and make sure the
sharpening is the last process, so changing to 8 bit has no influence on
the final result.

Art

Alan Harper wrote:

> I have a 16 bit scan of a photo that's on the large side (10,000 x
> 7,000 pixels), and I want to see if it benefits from sharpening.
> Photoshop seems to be unable to sharpen a 16-bit image. I tried to
> "scan from disk" in Vuescan and use the sharpening there (and also
> tried grain reduction). Vuescan may have improved these aspects of
> the photo, but the exposure and saturation went completely kerflooy
> (a technical term meaning awful). Anyone have some guidelines for
> settings for Vuescan that will apply sharpening and/or grain
> reduction, but not change the exposure, color, etc at all?
>
> If not, I'll continue in Photoshop.
>
> Vuescan for Mac OS-X if that matters.
>
> Alan
>


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