Lots of scanning software, but ....

[SS]

Is there anything that does anything while scanning that CANNOT be done
later (post processing) using software such as Photoshop? Hence the question
what software to use, especially on over/underexposed film (using film
scanner). Same question possibly applies to flatbeds but with prints. One
process for fim as an example is possibly infra red dust removal. Surely no
'post processing' software is as good at 'recognising' dust and scratches
and removing them?

 

[CSM1]

Is there anything that does anything while scanning that CANNOT be done
later (post processing) using software such as Photoshop? Hence the
question
what software to use, especially on over/underexposed film (using film
scanner). Same question possibly applies to flatbeds but with prints. One
process for fim as an example is possibly infra red dust removal. Surely
no
'post processing' software is as good at 'recognising' dust and scratches
and removing them?

Setting the original Black and White points must be done at the time of the
initial scan.
(A hardware setting that effects the data retrieved.)

You can not correct lost information in Post processing.

And the dICE is only available if the scanner has an infrared channel. No
dust and scratch software is as good as the infrared detection performed in
the scanner on the Film.

 

[Don]

Is there anything that does anything while scanning that CANNOT be done
later (post processing) using software such as Photoshop?

Exposure, focus and, possibly, ICE (IR based dust and scratches
removal). Everything else can be done afterwards.

One caveat re ICE. Technically, this could be done later if you save
the IR channel data and have the appropriate software to process it.
Unfortunately, ICE isn't capable of that for marketing reasons. :-/

Hence the question
what software to use, especially on over/underexposed film (using film
scanner). Same question possibly applies to flatbeds but with prints. One
process for fim as an example is possibly infra red dust removal. Surely no
'post processing' software is as good at 'recognising' dust and scratches
and removing them?

There are a few options such VueScan (permanently buggy and very
amateur), Polaroid (free download available, non-IR and not even close
to ICE), etc. Therefore, as I write above, this is theoretically
possible but practically not feasible because alternative software is
not in the same league as ICE for a number of reasons.

Having said that, since 'dust and scratches removal' is a one-off i.e.
you perform it and it's done as well as the software can do it, there
is little point in separating this process and doing it afterwards.
Especially since ICE, for example, does not even have the ability to
fine tune the clean up (other than the coarse: off, medium, high).

So, as things stand, there is really no major (any?) advantage to
separating dust and scratch removal.

Now, if ICE offered various fine tuning tweaking options (which I
would very much like to see!) then it would be a very useful feature
to separate this out and move it to post-processing.

Finally, if you really want to do this yourself you could use software
like VueScan to save this IR channel (i.e. scan raw) and then perform
dust and scratches removal manually in your image editing software.
There's plenty of advice on the net on how to do this. There is one
fly in the ointment and that's VueScan! It's notoriously buggy and
unreliable generating very corrupt output (if you look close enough).

So, any (questionable) gains you may theoretically achieve by doing
this yourself, would be wiped out even before you start because
VueScan output is so corrupt. In other words, even your best efforts
could not compensate for this handicap and, on balance and all things
considered, ICE on its own will therefore produce far better results.

Don.

 

[Don]

Setting the original Black and White points must be done at the time of the
initial scan.
(A hardware setting that effects the data retrieved.)

That is *not* correct!

There are *no* hardware Black and White point settings! All that is
done *after* the scan and can just as well be done in image editing
software in post-processing.

You can not correct lost information in Post processing.

That is very much true and the main reason for not letting scanning
software mess with the data coming off the scanner.

And the dICE is only available if the scanner has an infrared channel. No
dust and scratch software is as good as the infrared detection performed in
the scanner on the Film.

Also, very true.

Don.

 

[false_dmitrii]

That is *not* correct!

There are *no* hardware Black and White point settings! All that is
done *after* the scan and can just as well be done in image editing
software in post-processing.

Unless, of course, the scanner uses the White Point setting to adjust
its hardware exposure. I thought I'd read as much here regarding Epson
Scan.

<snip>

false_dmitrii

 

[CSM1]

I disagree.

When you set the Black and White points in the preview, the scanner makes a
final scan using the points you set for the output of the scan. It will
shift the data to cover the whole 8 or 16 bits output, thereby increasing
the dramatic range of the final scan. That is data that you would not have
in the output otherwise.

I have seen scanners affect the exposure based on the black and white points
set in the preview.

 

[Don]

Unless, of course, the scanner uses the White Point setting to adjust
its hardware exposure. I thought I'd read as much here regarding Epson
Scan.

Yes, you may (mis)use exposure to *try* (!) and perform the equivalent
of the White point setting (alone!) but, for starters, that would
leave the Black point "dangling" and corrupt image data.

White Point setting (by definition) also includes color correction and
simply setting exposure will not do that. Now, some scanners offer
individual channel adjustments but the "reward" for all that work of
setting *only* the White point would be data loss and corruption.

Namely, using exposure to set the White point in such a way (i.e. by
boosting channels individually) would also corrupt the image data.
Setting the White Point is linear. However, the media where the
characteristic curve is complex (e.g. Kodachrome is an extreme case
but this applies to all media) setting the White point using exposure
by modifying individual channels could therefore "misalign" the colors
in the rest of the image in a non-linear fashion and make subsequent
editing a nightmare.

Finally, using exposure to set the White point would be a bad idea on
another count. When setting exposure in this context it's always
advisable to pull back a couple of clicks in order to avoid clipping
and do the fine tuning in an image editor afterwards. That's because
of basing this crucial decision on low-res preview scan keyhole, etc.

Don.

 

[Don]

I disagree.

You give great advice here and I'm very appreciative you do that -
especially the time consuming chasing of all the links, etc. - but in
this instance, I'm sorry to say, you're wrong.

It's not a question of agreement but of fact. There is *no* Black and
White point setting in hardware. It's a software editing function.

When you set the Black and White points in the preview, the scanner makes a
final scan using the points you set for the output of the scan.

No, the scanner will scan the same regardless of B&W point setting.
Then, *AFTER* the scan, the scanner *software* will *edit* this scan
data based on those B&W settings. Nothing to do with hardware.

You seem to misunderstand how preview works. It's a *low resolution*
scan and thereby less accurate than the final scan i.e. potentially
causing further loss of data if used as an absolute indicator as you
do. That's why it's advisable to always *add* a few exposure clicks to
account for that and have some elbow room in the final (raw) scan.

Try this little test: Scan an image (all software settings off!) at
your preview resolution and then at full resolution, immediately one
after the other to minimize calibration drifting. Compare their
histograms and you will see they vary widely, much more than the
variations expected due to two scans. How much more depends on image
content. If the highlights are a steep "cliff" suddenly dropping to 0,
the difference will be relatively small. But if your highlights are a
thin, gently decreasing line, the differences will be massive!

It will
shift the data to cover the whole 8 or 16 bits output, thereby increasing
the dramatic range of the final scan. That is data that you would not have
in the output otherwise.

I'm sorry, but that's completely and totally wrong!

When you set B&W points in scanner software you are *LOSING* data!
Data gets *clipped* at both ends!!! That's *less* dynamic range.

All B&W point setting does is just *stretch* a *portion* of the total
dynamic range available in the scan! Not only that, but it usually
includes automatic clipping! All in all, less dynamic range, not more.

I have seen scanners affect the exposure based on the black and white points
set in the preview.

No, you haven't! You think you have seen that because of the
misunderstanding of what actually happens (please see above).

What you have seen is image appearing as having more contrast. You
could do exactly the same thing (much better and more accurate,
actually!) by scanning without scanner software B&W setting and
applying this contrast in an image editor afterwards. This will be
based on *actual* image data, not preview *guesswork*!

The bottom line is, there is no hardware B&W point setting in
hardware. It's an image editing software function.

Don.

 

[ian lincoln]

hi there. found white point grey point and black point in photoshop
elements 4 under lighting. levels. 3 eye dropper tools one for black white
and grey. great for restoring the faded photos. i bumped into it but lost
it but there is another one for dealing with colour casts.

As for determining what i presume is the mid grey i don't know so i left it
out. As for properly interpreting a histogram i still haven't a clue.

 

[Surfer!]

hi there. found white point grey point and black point in photoshop
elements 4 under lighting. levels. 3 eye dropper tools one for black white
and grey. great for restoring the faded photos. i bumped into it but lost
it but there is another one for dealing with colour casts.

As for determining what i presume is the mid grey i don't know so i left it
out. As for properly interpreting a histogram i still haven't a clue.

If it doesn't reach the RH end then you need to stretch it in that
direction which is what the white point tool does. The black point tool
does the same for the LH end. Images with a restricted histogram lack
contrast and sparkle.

OTOH if the histogram is chopped at either end then you have either lost
the shadow detail (LH) or blown the highlights (RH) - the equivalent of
under- or over- exposure.

 

[Don]

As for determining what i presume is the mid grey i don't know so i left it
out.

The software is often misleading by calling it "mid-grey". That's
really a misnomer and a more accurate term is "neutral". This may
sound like nitpicking but it actually goes to the core of the matter.

In other words, an area of the image which *should* be neutral, but it
isn't. And this doesn't have to be mid-gray (i.e. 127,127,127) either!
Clicking on such an area with the "neutral" color picker will then
remove any mid-range casts present in the image.

In Photoshop this defaults to 127,127,127 but it doesn't have to be.
That can be changed. But even if it is set to the mid-point one can
still click on other "should be neutral" parts of the image and that
will still remove the mid-range cast!

As for properly interpreting a histogram i still haven't a clue.

There are basically two camps here: the "scientists" and the
"artists". The artists ignore (hate!) the histogram and go by "what
feels right". The scientists a.k.a. "histogram worshipers" love the
histogram!

I personally firmly fall in the second category. In a nutshell, the
histogram is *objective* image information. The rule-of-thumb goal is
to set the black and white points in such a way so as to get as close
to the edges as possible but don't do damage. However, that's just the
beginning because there are other considerations (see below).

Setting the black and white points will also help remove casts, with
the neutral point as the last step to "mop up" any remaining casts in
the mid-range. As with the neutral point, you use the black and white
points by clicking on an area of the image which should be black and
white, respectively. Increase the sampling areas to maximum to improve
accuracy. In Photoshop this means use 5x5 instead of 1x1 pixel square.

Finally, those "other considerations". Even though in theory the black
point in an image should have the color value of 0,0,0 (after the
correction) in reality that's often "too black" and makes it hard to
see in the shadows. Therefore, one common procedure is to move this
black point a little bit up. The white point is somewhat the opposite.
Namely, trying to preserve everything in the white point is often
counter-productive since white point data is reflections and other
"blown" area of the image which contain no meaningful image content
anyway. Therefore, one common procedure is to "clip" this and move the
white point a little bit down.

Anyway, all this only scratches the surface but it's a start...

Don.

 

[ian lincoln]

Anyway, all this only scratches the surface but it's a start...

Don.

Thanks don. I've been using the eye droppers to restore old faded photos.
the results are good and i simply ignore the shape of the histogram.

 

[Don]

Thanks don. I've been using the eye droppers to restore old faded photos.
the results are good and i simply ignore the shape of the histogram.

You're most welcome, Ian. Setting the black and white points (which,
effectively, means increasing contrast) will restore fading very
nicely. It's also good to use the "gray" picker (click on a shadow or
concrete, or some other known "neutral" area) because colors fade at
different rates, meaning, there is bound to be a cast present after
the B&W points have been adjusted.

Don.

 

[Alan Meyer]

Is there anything that does anything while scanning that CANNOT be done
later (post processing) using software such as Photoshop? Hence the question
what software to use, especially on over/underexposed film (using film
scanner). Same question possibly applies to flatbeds but with prints. One
process for fim as an example is possibly infra red dust removal. Surely no
'post processing' software is as good at 'recognising' dust and scratches
and removing them?

I haven't discovered anything that I could do in the scanner software
that I couldn't do as well or better using my regular photo editor
(the GIMP.)

However, for many of my scans, I use the scanner software anyway
because of the convenience. When I'm scanning old snapshots that
aren't that great prints or great photos to being with, and all I want is
to preserve the image, I don't want to fool with post processing.

When I'm scanning something important, then I go easy on the
scanner software processing and do some more serious work in
the GIMP.

Alan

 

[One4All]

C'mon, CSM1, it's *dynamic,* not *dramatic* range. Are you dyslexic? If
so, I apologize.

 

[CSM1]

C'mon, CSM1, it's *dynamic,* not *dramatic* range. Are you dyslexic? If
so, I apologize.

No, I am not dyslexic, but you are correct, I missed the word.
My spell checker does not have a grammar checker.

But you got to admit the dynamic range can be dramatic