Various Topics on Scanners

.... ..l..

I'm new to this scanner malarkey, so please bear with me:

I'm scanning some negatives, using Nikon Scan and a Coolscan V. What I
want to achieve is to batch scan the film strips with the minimum of
user intervention, both to save time, and also to enable me to do
something else whilst scanning. I only want to handle the negs once, so
I scan them at the highest settings, in 14bit and with ICE & GEM set on,
saving them as uncropped, 'flat' TIFFs.

So far, so good. Until I noticed some of my scans had a colour cast.
Mostly blue, but in one extreme example, a deep blue sky was rendered
green. When looking at the individual RGB levels in Photoshop, I notice
that they are bunched up in the centre. Low contrast I think. Picking
the shadow and highlight points for all 3 channels more or less removes
the colour cast. I seem to be able to achieve the same thing using the
midpoint picker in the Nikon Scan curves tool.

What I what to know is, is there a difference in using these two
solutions? As I said earlier, I want to batch scan as much as possible
and I don't mind having to tweak the scans at a later date, using PS6.
I'm concerned about changing any setting in NS from 'default' as using
these settings, many of my scans seem to have correct colour and wonder
if these would then 'go the other way', IYSWIM.

Essentially, what I'm asking is: Is there any difference between
tweaking levels / curves in Photoshop, and getting the scan 'right' in
the first place?

TIA.
--
Alex Wilde

..gr..

Are you letting NS set the exposure ?

Yes there is a difference between bunching up all of the density range
of the neg over a few bits of the A/D converter ( think using 6 bits out
of the 14 !) and using all 14 bits. You will loose the distinctions in
tone of the image. Whether it is visible to you are not depends on how
much of the density range the neg used for the image to begin with. If
it was reasonably exposed , then you should see the difference in the
two scans, at least partially on the CRT. If your image is only using 8
bits of density range or less , then you will not likely see any
difference in the CRT (8 bit /pixel device) between the two scans. The
extra "headroom" bits will help when you are adjusting the image in PS.
We have worked with 8 bit per pixel images for years and done quite
well, you just had to get the scan correct (setting white and black
points) to begin with and then limit the size of any curve edits to the
image.


Alex Wilde wrote:
> I'm new to this scanner malarkey, so please bear with me:
>
> I'm scanning some negatives, using Nikon Scan and a Coolscan V. What I
> want to achieve is to batch scan the film strips with the minimum of
> user intervention, both to save time, and also to enable me to do
> something else whilst scanning. I only want to handle the negs once, so
> I scan them at the highest settings, in 14bit and with ICE & GEM set on,
> saving them as uncropped, 'flat' TIFFs.
>
> So far, so good. Until I noticed some of my scans had a colour cast.
> Mostly blue, but in one extreme example, a deep blue sky was rendered
> green. When looking at the individual RGB levels in Photoshop, I notice
> that they are bunched up in the centre. Low contrast I think. Picking
> the shadow and highlight points for all 3 channels more or less removes
> the colour cast. I seem to be able to achieve the same thing using the
> midpoint picker in the Nikon Scan curves tool.
>
> What I what to know is, is there a difference in using these two
> solutions? As I said earlier, I want to batch scan as much as possible
> and I don't mind having to tweak the scans at a later date, using PS6.
> I'm concerned about changing any setting in NS from 'default' as using
> these settings, many of my scans seem to have correct colour and wonder
> if these would then 'go the other way', IYSWIM.
>
> Essentially, what I'm asking is: Is there any difference between
> tweaking levels / curves in Photoshop, and getting the scan 'right' in
> the first place?
>
> TIA.

.... ..l..

In message <miMeg.102885$dW3.36597@newssvr21.news.prodigy.com >, degrub
<degrub@nospamflash.net> writes
>Are you letting NS set the exposure ?

Yes.
>
>Yes there is a difference between bunching up all of the density range
>of the neg over a few bits of the A/D converter ( think using 6 bits
>out of the 14 !) and using all 14 bits. You will loose the distinctions
>in tone of the image. Whether it is visible to you are not depends on
>how much of the density range the neg used for the image to begin with.
>If it was reasonably exposed , then you should see the difference in
>the two scans, at least partially on the CRT. If your image is only
>using 8 bits of density range or less , then you will not likely see
>any difference in the CRT (8 bit /pixel device) between the two scans.
>The extra "headroom" bits will help when you are adjusting the image in
>PS. We have worked with 8 bit per pixel images for years and done quite
>well, you just had to get the scan correct (setting white and black
>points) to begin with and then limit the size of any curve edits to the image.
>
I think I understand that. Given what you said the your last sentence,
is trying to archive negative scans 'unattended' a futile task? Maybe my
workflow needs rethinking.

What I can't understand is why some scans are bunched up as described,
and others okay - both seemingly of very similar contrast / exposure.
This is why I am worried about applying a 'global' curves setting to the
scans. In making the some right, surely I'm making others worse? If this
is the case, then my goal of almost uninterrupted scanning of negs is a
none starter.


--
Alex Wilde

..n ..itz..

Alex Wilde wrote:

> In message <miMeg.102885$dW3.36597@newssvr21.news.prodigy.com >, degrub
> <degrub@nospamflash.net> writes
>
>> Are you letting NS set the exposure ?
>
>
> Yes.
>
>>
>> Yes there is a difference between bunching up all of the density range
>> of the neg over a few bits of the A/D converter ( think using 6 bits
>> out of the 14 !) and using all 14 bits. You will loose the
>> distinctions in tone of the image. Whether it is visible to you are
>> not depends on how much of the density range the neg used for the
>> image to begin with. If it was reasonably exposed , then you should
>> see the difference in the two scans, at least partially on the CRT. If
>> your image is only using 8 bits of density range or less , then you
>> will not likely see any difference in the CRT (8 bit /pixel device)
>> between the two scans. The extra "headroom" bits will help when you
>> are adjusting the image in PS. We have worked with 8 bit per pixel
>> images for years and done quite well, you just had to get the scan
>> correct (setting white and black points) to begin with and then limit
>> the size of any curve edits to the image.
>>
> I think I understand that. Given what you said the your last sentence,
> is trying to archive negative scans 'unattended' a futile task? Maybe my
> workflow needs rethinking.
>
> What I can't understand is why some scans are bunched up as described,
> and others okay - both seemingly of very similar contrast / exposure.
> This is why I am worried about applying a 'global' curves setting to the
> scans. In making the some right, surely I'm making others worse? If this
> is the case, then my goal of almost uninterrupted scanning of negs is a
> none starter.

Hi Alex...

Experienced much of what you're seeing as well (archiving negs
that span many, many years)

I'm pretty much convinced that what's happening is that our
brain is doing a *lot* of pre or post or somewhere in between
of what the eye actually sees and what our brain thinks it should
see.

IOW, the eye can be fooled, but not the scanner.

FWIW, I'm three years into scanning negs and slides, and still
a little of half way through the pile... doing 'em one by one

Take care.

Ken

..gr..

Another method of attack is to batch them and then go back and manually
scan the ones that are not good enough.


Ken Weitzel wrote:
>
>
> Alex Wilde wrote:
>
>> In message <miMeg.102885$dW3.36597@newssvr21.news.prodigy.com >, degrub
>> <degrub@nospamflash.net> writes
>>
>>> Are you letting NS set the exposure ?
>>
>>
>>
>> Yes.
>>
>>>
>>> Yes there is a difference between bunching up all of the density
>>> range of the neg over a few bits of the A/D converter ( think using 6
>>> bits out of the 14 !) and using all 14 bits. You will loose the
>>> distinctions in tone of the image. Whether it is visible to you are
>>> not depends on how much of the density range the neg used for the
>>> image to begin with. If it was reasonably exposed , then you should
>>> see the difference in the two scans, at least partially on the CRT.
>>> If your image is only using 8 bits of density range or less , then
>>> you will not likely see any difference in the CRT (8 bit /pixel
>>> device) between the two scans. The extra "headroom" bits will help
>>> when you are adjusting the image in PS. We have worked with 8 bit per
>>> pixel images for years and done quite well, you just had to get the
>>> scan correct (setting white and black points) to begin with and then
>>> limit the size of any curve edits to the image.
>>>
>> I think I understand that. Given what you said the your last sentence,
>> is trying to archive negative scans 'unattended' a futile task? Maybe
>> my workflow needs rethinking.
>>
>> What I can't understand is why some scans are bunched up as described,
>> and others okay - both seemingly of very similar contrast / exposure.
>> This is why I am worried about applying a 'global' curves setting to
>> the scans. In making the some right, surely I'm making others worse?
>> If this is the case, then my goal of almost uninterrupted scanning of
>> negs is a none starter.
>
>
> Hi Alex...
>
> Experienced much of what you're seeing as well (archiving negs
> that span many, many years)
>
> I'm pretty much convinced that what's happening is that our
> brain is doing a *lot* of pre or post or somewhere in between
> of what the eye actually sees and what our brain thinks it should
> see.
>
> IOW, the eye can be fooled, but not the scanner.
>
> FWIW, I'm three years into scanning negs and slides, and still
> a little of half way through the pile... doing 'em one by one
>
> Take care.
>
> Ken
>

..n

On Mon, 29 May 2006 17:51:20 +0100, Alex Wilde
<awilde@cizeta.demon.co.uk> wrote:

>So far, so good. Until I noticed some of my scans had a colour cast.
>Mostly blue, but in one extreme example, a deep blue sky was rendered
>green. When looking at the individual RGB levels in Photoshop, I notice
>that they are bunched up in the centre. Low contrast I think. Picking
>the shadow and highlight points for all 3 channels more or less removes
>the colour cast. I seem to be able to achieve the same thing using the
>midpoint picker in the Nikon Scan curves tool.
>
>What I what to know is, is there a difference in using these two
>solutions? As I said earlier, I want to batch scan as much as possible
>and I don't mind having to tweak the scans at a later date, using PS6.
>I'm concerned about changing any setting in NS from 'default' as using
>these settings, many of my scans seem to have correct colour and wonder
>if these would then 'go the other way', IYSWIM.

A couple of things here. First of all, it's normal to have the
histograms bunched up in the middle in case of negatives. The dynamic
range (the difference between brightest and darkest points in an
image) is compressed on negatives. Your scanner has much more dynamic
range than that so the negatives end up only occupying a portion (the
middle) of this full scanner range.

So, if you don't do any image editing during scanning i.e. scan "raw"
the histograms are bunched up in the middle (or elsewhere, depending
on the exposure).

>Essentially, what I'm asking is: Is there any difference between
>tweaking levels / curves in Photoshop, and getting the scan 'right' in
>the first place?

No. That's a common misconception. Scanner software is actually
composed of two *unrelated* components: the actual scanning (i.e.
getting data from the scanner) and the editing tools.

So, in theory, it doesn't matter if you let the scanner software do
everything in one big gulp (i.e. scan and edit together) or scan "raw"
and do you edits later.

However, in practice scanner software editing tools are usually a poor
substitute (i.e. a very limited quick-and-dirty subset) of standalone
external editors like Photoshop. They exist only for marketing reasons
and people for whom that's good enough and they can't justify the cost
of a dedicated editor or wish to spend the extra time.

In case of NikonScan and Photoshop *6* there is one arcane
complication. This is really "out there" in the pedantic land, so you
can skip it. But here's the mind twister for completeness:

The 16-bit editing mode in Photoshop *6* is actually only 15-bit!
However, since CoolScan V is 14-bit that shouldn't be a problem,
right? Well, it is because gamma and calibration of this raw 14-bit
data is done using the full 16-bits in NikonScan. So, in theory you
may lose some data. But wait, there's more! ;o) Since you're scanning
negatives, they have a (vastly) reduced dynamic range, you will never
push at the limits of 14-bit let alone 16.

So, the bottom line in case of negatives is, you can skip that last
paragraph! ;o)

Don.