Question about colour depth for scanner

Another newbie question.

My slide scanner (PF3650Pro3) can scan at 8 or 16 bit colour depth.
However, if I manipulate an image scanned at 16 bit depth, on saving it is
changed to 8 bit by the software. I have tried Photoshop element,
Paintshop Pro & Gimp - all change the colour depth to 8 bit. Is there any
benefit of scanning at 16 bit colour depth as almost all scanned images
need some sort of manipulation. Scanning at 16 bit takes significantly
longer than at 8 bit.

--

Gautam Majumdar

Please send e-mails to

Gautam Majumdar wrote:
Another newbie question.

My slide scanner (PF3650Pro3) can scan at 8 or 16 bit colour depth.
However, if I manipulate an image scanned at 16 bit depth, on saving it is
changed to 8 bit by the software. I have tried Photoshop element,
Paintshop Pro & Gimp - all change the colour depth to 8 bit. Is there any
benefit of scanning at 16 bit colour depth as almost all scanned images
need some sort of manipulation. Scanning at 16 bit takes significantly
longer than at 8 bit.


I assume you mean 8 bits per color. Paint Shop Pro, and perhaps the other programs you mention, only work with images having
8 bits/color or less. In any case, if you are scanning photographic prints, the color range of the print is less than 8
bits/color. That is true also for most negatives. Scanning with more color depth only lets you be less careful about
setting scanning parameters,

"Gautam Majumdar" wrote in message
k...
Another newbie question.

My slide scanner (PF3650Pro3) can scan at 8 or 16 bit colour depth.
However, if I manipulate an image scanned at 16 bit depth, on saving it is
changed to 8 bit by the software. I have tried Photoshop element,
Paintshop Pro & Gimp - all change the colour depth to 8 bit. Is there any
benefit of scanning at 16 bit colour depth as almost all scanned images
need some sort of manipulation. Scanning at 16 bit takes significantly
longer than at 8 bit.

Well, Photoshop doesn't change from 16 bit to 8 bit all by itself.
Eventually, however, you might as well change to 8 bits because the printers
expect 8 bit depth.
Jim

Photoshop CS can handle many (not all) processes in 16 bit.
Ideally 16 bit offers a wider color gamut.
Reality is somewhat different.
It is not clear that your monitor can reproduce the entire 16 bit gamut or
that most people can actually discriminate that tonal range.
Then there is the problem of printing.
Printers operate in an 8 bit world.
Printer gamuts do not coincide with the entire 8 bit gamut anyway. Then
there are the issues of paper surface, reflectivity, ambient lighting, etc.
At some point your 16 bit masterpiece will be truncated to 8 bits anyway
using an immutable algorithm in an unadjustable driver. As a result when
printing a 16 bit image color matching may be more prone to distortion than
if the image is always 8 bit (Epson has educational materials discussing
this).
16 bit color is an acquired skill and unless you have Photoshop CS is not
available to you anyway.
You are not really missing anything important to most people.

"Gautam Majumdar" posted:
"...
I have tried Photoshop element,
Paintshop Pro & Gimp -
...."

None of those programs work in the "16-bit" color space.

Use a program that can ... such as

PhotoShop CS
Picture Window (Pro)
CinePaint




"Gautam Majumdar" wrote in message
k...
Another newbie question.

My slide scanner (PF3650Pro3) can scan at 8 or 16 bit colour depth.
However, if I manipulate an image scanned at 16 bit depth, on saving it
is
changed to 8 bit by the software. I have tried Photoshop element,
Paintshop Pro & Gimp - all change the colour depth to 8 bit. Is there any
benefit of scanning at 16 bit colour depth as almost all scanned images
need some sort of manipulation. Scanning at 16 bit takes significantly
longer than at 8 bit.

--

Gautam Majumdar

Please send e-mails to

"Gautam Majumdar" posted:
"...
I have tried Photoshop element,
Paintshop Pro & Gimp -
...."

None of those programs work in the "16-bit" color space.

Use a program that can ... such as

PhotoShop CS
Picture Window (Pro)
CinePaint




"Gautam Majumdar" wrote in message
k...
Another newbie question.

My slide scanner (PF3650Pro3) can scan at 8 or 16 bit colour depth.
However, if I manipulate an image scanned at 16 bit depth, on saving it
is
changed to 8 bit by the software. I have tried Photoshop element,
Paintshop Pro & Gimp - all change the colour depth to 8 bit. Is there any
benefit of scanning at 16 bit colour depth as almost all scanned images
need some sort of manipulation. Scanning at 16 bit takes significantly
longer than at 8 bit.

--

Gautam Majumdar

Please send e-mails to

Gautam Majumdar wrote:
Another newbie question.

My slide scanner (PF3650Pro3) can scan at 8 or 16 bit colour depth.
However, if I manipulate an image scanned at 16 bit depth, on saving it is
changed to 8 bit by the software. I have tried Photoshop element,
Paintshop Pro & Gimp - all change the colour depth to 8 bit. Is there any
benefit of scanning at 16 bit colour depth as almost all scanned images
need some sort of manipulation. Scanning at 16 bit takes significantly
longer than at 8 bit.


You need a photo editor that has full 16-bit support,
like photoshop CS.

The is a definite improvement in image quality to film
scanned with 12-bits/channel (16-bit/channel) output.
The main benefits are the ability to pull more
detail out of the shadows and highlights. In fact,
I reduced my use of split density filters when I switched
to 16-bit scanning as I found I could pull detail out
of very bright clouds that with 8-bit scans appeared
essentially white.

Example: The 4x5 image was done on fuji velvia with
no split density filter:
http://www.clarkvision.com/galleries...a+b.c-700.html
yet detail in the clouds is quite clear. On the film, they
were quite bright, almost all white when looking at the
slide on the light table. Previous to 16-bit scanning, I would
have used a split density filter to reduce the cloud
brightness.

Roger Clark
http://www.clarkvision.com

There is usually normalization going on that alters the level of the
8-bit per color image file based on info from all 16 bits. This is
very much like what happens in most cameras when file is not saved as
RAW file. So you do gain, just not as much as if the final output
file had all 16 bits (so you could alter brightness/contrast yourself).

There is usually normalization going on that alters the level of the
8-bit per color image file based on info from all 16 bits. This is
very much like what happens in most cameras when file is not saved as
RAW file. So you do gain, just not as much as if the final output
file had all 16 bits (so you could alter brightness/contrast yourself).

There is usually normalization going on that alters the level of the
8-bit per color image file based on info from all 16 bits. This is
very much like what happens in most cameras when file is not saved as
RAW file. So you do gain, just not as much as if the final output
file had all 16 bits (so you could alter brightness/contrast yourself).