unsharp mask?

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Kennedy said:
If you take the same attitude with all of the Photoshop features then
you will not want anything to do with any of them - for example, all you
have to do is take a look at a few 'Photoshopped' images on the net and
you will quickly find examples which have been ruined by inappropriate
or excessive use of USM. The fact that a filter can be used badly does
not mean they are "worse than useless", simply that the user doesn't
know what they are or what they are doing.

You may not be interested in finding out, and that is fine - there are
plenty of tools in PS that many users avoid completely because they have
a preferred workflow or no need for the use. But to publicly condemn a
tool because you have no interest in using it is complete arrogance.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's pissed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
Click to expand...


I don't use Photoshop, but avoid most filters in other programs
because they are so gross in their treatment of photos--as in can only be
applied to heavily, losing definition of what the original was. I find
that the size of the untouched photo has a lot to do with how successful
the effect is. I will say that Earlier Adobe filters (from the PS5 era,
that work with Paint Shop Pro, are better than what PSP provides, and use
them in preference to PSPs. Unsharp mask isn't really an effect, but I
can sympathize with the frustation of wanting something to work and not
being able to get a good-looking result. One of my favorite tricks with
PSP is to use "edge preserving smooth" (under Noise) then "sharpen more"
(which would usually outline everything so heavily that the photo looks
phony) when I have a photo that is a little blurred. If you don't look
close sometimes the result is acceptable.

Brendan
--
 
Brendan R. Wehrung said:
I don't use Photoshop, but avoid most filters in other programs
because they are so gross in their treatment of photos--as in can only be
applied to heavily, losing definition of what the original was.
Click to expand...

Well, for those who find even USM unacceptable - and there are plenty
who do - but find the fixed levels of sharpening too limited, Photoshop
CS introduced "Smart Sharpen": all the flexibility and more of USM but
in a sharpening filter. The results are, apparently, considerably
superior to USM but, since I don't use CS yet, I cannot confirm or deny
that.
I find
that the size of the untouched photo has a lot to do with how successful
the effect is.
Click to expand...

Of course it will - that is one of the main reasons why sharpening or
USM should be left until just before printing.
 
Yes, you have a problem using them and the standard levels are, by no
means, as flexible as the USM, but your claims are ridiculously
exaggerated.
Click to expand...

OK. Look, we are going to disagree and never the twain shall meet and
all that... In any case, I'm not going to get into an argument when
you're using comments such as "ridiculously exaggerated". I value
your opinion even when we disagree, so I'm going to leave it at that
in case this gets heated.

--

Hecate - The Real One
(e-mail address removed)
Fashion: Buying things you don't need, with money
you don't have, to impress people you don't like...
 
Hecate said:
I'm not going to get into an argument when
you're using comments such as "ridiculously exaggerated".
Click to expand...

However you are quite happy to do so by using comments like "they'll
make a mess" and "worse than useless".

"Oh would some Power the gift to give us,
To see ourselves as others see us!
It would from many a blunder free us,
And foolish notion"
;-)
 
Well, for those who find even USM unacceptable - and there are plenty
who do - but find the fixed levels of sharpening too limited, Photoshop
CS introduced "Smart Sharpen": all the flexibility and more of USM but
in a sharpening filter. The results are, apparently, considerably
superior to USM but, since I don't use CS yet, I cannot confirm or deny
that.
Click to expand...

Actually, that's CS2 and yes, I've been told that too, but I have yet
to see anyone put up demonstrable proof :)

--

Hecate - The Real One
(e-mail address removed)
Fashion: Buying things you don't need, with money
you don't have, to impress people you don't like...
 
SNIP
Well, for those who find even USM unacceptable - and there are
plenty who do - but find the fixed levels of sharpening too limited,
Photoshop CS introduced "Smart Sharpen": all the flexibility and
more of USM but in a sharpening filter. The results are,
apparently, considerably superior to USM but, since I don't use CS
yet, I cannot confirm or deny that.
Click to expand...

Its effect looks a lot like "deconvolution sharpening" with an
"edgemask" and "blending control", in other words rather good ;-)
BTW, it was introduced with CS2.

Bart
 
Well, you'll wait a long time if you want absolute demonstrable proof,
by which time I expect Photoshop itself to be pretty obsolete, but there
are a couple of demonstrable examples around on the web. For example:
http://graphicssoft.about.com/od/photoshop/ss/cs2smartsharpen.htm
Click to expand...

Actually, I don't think there's any way to absolute proof of anything
in most cases ;-)

Demonstrable is different i.e. it looks better. And from what I can
see from that link they just may have done that.

Also, from what Bart says I think that's probably one of the reasons I
shall use to convince myself to upgrade ;-)

--

Hecate - The Real One
(e-mail address removed)
Fashion: Buying things you don't need, with money
you don't have, to impress people you don't like...
 
Kennedy McEwen said:
Well, you'll wait a long time if you want absolute demonstrable proof, by
which time I expect Photoshop itself to be pretty obsolete, but there are
a couple of demonstrable examples around on the web. For example:
http://graphicssoft.about.com/od/photoshop/ss/cs2smartsharpen.htm
Click to expand...

Hmm. I still see halos, even with smart sharpen.

I really hate halos: they largely appear on edges that are already contrasty
enough that they don't need any sharpening in the first place.

David J. Littleboy
Tokyo, Japan
 
Recently said:
Hmm. I still see halos, even with smart sharpen.

I really hate halos: they largely appear on edges that are already
contrasty enough that they don't need any sharpening in the first
place.
Click to expand...
Those kinds of artifacts are the result of applying global filters to
images. It's a "quick-and-dirty" approach to image making. I don't see
anything in these examples that can't be accomplished with the tools
available in earlier versions of PS, Adobe appears to be simply combining
them into a single tool.

Neil
 
David J. Littleboy said:
Hmm. I still see halos, even with smart sharpen.

I really hate halos: they largely appear on edges that are already contrasty
enough that they don't need any sharpening in the first place.
Click to expand...
Isn't that telling you something?

Why are you applying global sharpening to an image which already has
sharp content - the result can only ever be over-sharpened, and that
means halos and ringing edges.
 
SNIP
Hmm. I still see halos, even with smart sharpen.

I really hate halos: they largely appear on edges that are already
contrasty enough that they don't need any sharpening in the first
place.
Click to expand...

I agree, small halos are *only* permissible when anticipating losses
further up the image chain (e.g. pre-compensating for printing losses,
dot gain). Fortunately the issue is largely controlable with the
following blending approach:
<http://www.xs4all.nl/~bvdwolf/main/downloads/Non-clipped-sharpening.png>
which reduces sharpening at already contrasty edges.
The parameters of the smart sharpening plug-in allow to do that at
sharpening time, but doing it later allows for more control, because
layer opacity will provide additional control for mid-tones.

Bart
 
Bart van der Wolf said:
I agree,
Click to expand...

Hmm. So I'm not off the wall said:
small halos are *only* permissible when anticipating losses further up the
image chain (e.g. pre-compensating for printing losses, dot gain).
Click to expand...

But, as you've pointed out, that sharpening function is best provided in the
printer dirver driver (i.e. Qimage). Which brings us back to halos being
something that one should never see.
Fortunately the issue is largely controlable with the following blending
approach:
<http://www.xs4all.nl/~bvdwolf/main/downloads/Non-clipped-sharpening.png>
which reduces sharpening at already contrasty edges.
Click to expand...

That sounds like the right thing, but all I see is an empty image in
photoshop.
The parameters of the smart sharpening plug-in allow to do that at
sharpening time, but doing it later allows for more control, because layer
opacity will provide additional control for mid-tones.
Click to expand...

Hmm. I try to avoid layers. 4000 dpi scans of 6x7 are large enough as it
is...

Ah. This time I got the download. That's a screenshot of something.
Presumable the "smart sharpening plug-in". Will it run in Photoshop 7? And
where do I find it?

David J. Littleboy
Tokyo, Japan
 
Kennedy McEwen said:
Isn't that telling you something?
Yes.

Why are you applying global sharpening to an image which already has sharp
content - the result can only ever be over-sharpened, and that means halos
and ringing edges.
Click to expand...

(Well, I'm not: the folks on the page referenced above are.)

Sharpening at levels that does very nice things to much of the image
(textures, low contrast detail) makes a mess of edges that are easily
described mathematically.

What I want is a sharpening function whose strength goes down as edge
contrast goes up. That should be pretty simple...

David J. Littleboy
Tokyo, Japan
 
What I want is a sharpening function whose strength goes down as edge
contrast goes up. That should be pretty simple...
Click to expand...

You can make an action in Photoshop to do this. Something like the following:

Switch to LAB mode
Duplicate layer
Add a layer mask
Select the mask
Use Apply Image to apply the lightness channel to the mask
Perform a gaussian blur (experiment to find the best radius for you) on the
layer mask.
Select Apply Image again, and reapply the lightness channel, using
"difference" instead of "normal". This should pick out the contrasty edges.
Invert the layer mask
Do "auto contrast" on the layer mask

Now you can experiment using Unsharp Mask on the lightness channel of your
new layer. It'll sharpen the whole channel, but where there was already high
contrast, the original image below will show through. You can vary the
extent by doing a levels edit on the layer mask, and moving the sliders
about to see the differing effects. Once you're happy, select "flatten
image", and you're done.

Bear in mind that if the image is even slightly noisy, this will probably
do a wonderful job of sharpening the noise, however...
 
David J. Littleboy said:
(Well, I'm not: the folks on the page referenced above are.)

Sharpening at levels that does very nice things to much of the image
(textures, low contrast detail) makes a mess of edges that are easily
described mathematically.

What I want is a sharpening function whose strength goes down as edge
contrast goes up. That should be pretty simple...
Click to expand...

There are products and tutorials on how to create highly controllable
edge masks before sharpening. I think that's what you are looking for.
Go to creativepro.com and search for such a tutorial by Bruce Fraser, or
purchase his Photokit sharpener. Caution, some of these can increase the
file size significantly.
 
SNIP
Ah. This time I got the download. That's a screenshot of something.
Presumable the "smart sharpening plug-in". Will it run in Photoshop
7? And where do I find it?
Click to expand...

I know the constraints of adding a layer (large scans get twice as
large, temporarily), but you'll need to add one to be able and do
selective edge sharpening based on contrast. Try it on a crop and see
if you like it. Added benefit is that you can very selectively modify
the layer to only sharpen edges and not graininess, before you flatten
the result.

This works with all PS versions that allow to blend layers.

On the top duplicate layer (or merge of all visible layers) you apply
whatever sharpening you prefer. It's best to first change the
duplicate's layer blending as indicated; Luminocity to avoid
introduction of gamma adjusted color artifacts, and a gradual blending
of the sharpened layer as function of the original's edge contrast.
The two examples at the top show the resulting effect on the small
radius sharpening of two partial gradients, as the original contrast
increases, the sharpening is reduced.

Some of the controls in the new CS2 "Smart Sharpening" filter, allow
to achieve almost the same with only one layer, but I usually still
use the above blending layer method because of ther increased control.

The effect of Qimage's Batch filter>Adjust>"Sharpness equalizer" looks
very much like the above Photoshop approach, if you set the equalizer
to 90 - 100 with a radius of 1, and a large amount to your taste (I
find 500% often works, sometimes less, sometimes more). It obviously
doesn't allow to apply different sharpening to edges.

Bart
 
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