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sharpen vs unsharp mask & proper usage.

 
 
jmc
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      01-23-2005
Question on sharpening. I have a choice of various sharpen levels,
including directional, plus a couple levels of Unsharp Mask, and
Unsharp Mask Gaussian in the program I mainly use for light image
processing, ThumbsPlus. I also have Photoshop Elements, which I use
when TP can't handle the job.

Now, I've read here that most digital images can benefit from
sharpening. I mainly use the Gaussian version.

However, I've been wondering - when is it appropriate to use sharpen, as
opposed to an unsharp mask? When is Gaussian not a good idea (and how
is it different than the regular version?) Which one is better to try
to fix a slightly motion-blurred image, as opposed to a slightly
out-of-focus image? When would a directional sharpen work?

If I have a photo with noise that needs to be sharpened, do I sharpen
first then reduce noise, or vice versa?

If there's a place I can go to read about this, please point me there.

Appreciate your help.
 
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Charles Schuler
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      01-23-2005
This might help you:

http://www.russellbrown.com/images/t...Sharpening.mov


 
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paul
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      01-23-2005
Charles Schuler wrote:

> This might help you:
>
> http://www.russellbrown.com/images/t...Sharpening.mov


I'll have to check that out. Those video tutorials are great.

My understanding is 'regular' sharpening is just a generic light sharpen
that normally works fine. If it's not OK, use unsharp mask & set a
radius of just 1/3 to maybe three pixels & intensity of around 300. I
never messed with threshold.

Zoom in to 800% (control-plus) so you can see exactly what's happening
and you will understand intuitively while playing with the sliders.

Sharpening is always done last as it will otherwise emphasize the noise
or colors you are trying to adjust away. It needs to be done for each
time you reduce (even thumbnails) though it's not clear to me there is
any damage in sharpening the large one then re-shaprening for web/email
versions it perhaps is not ideal.
 
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Tony
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      01-23-2005
Sharpening should be the very last thing you do. Have the image preped for
final output before sharpening and save a version that is not sharpened so
you can go back if you are going to o to a different output.

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"jmc" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Question on sharpening. I have a choice of various sharpen levels,
> including directional, plus a couple levels of Unsharp Mask, and
> Unsharp Mask Gaussian in the program I mainly use for light image
> processing, ThumbsPlus. I also have Photoshop Elements, which I use
> when TP can't handle the job.
>
> Now, I've read here that most digital images can benefit from
> sharpening. I mainly use the Gaussian version.
>
> However, I've been wondering - when is it appropriate to use sharpen, as
> opposed to an unsharp mask? When is Gaussian not a good idea (and how
> is it different than the regular version?) Which one is better to try
> to fix a slightly motion-blurred image, as opposed to a slightly
> out-of-focus image? When would a directional sharpen work?
>
> If I have a photo with noise that needs to be sharpened, do I sharpen
> first then reduce noise, or vice versa?
>
> If there's a place I can go to read about this, please point me there.
>
> Appreciate your help.



 
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Stacey
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      01-24-2005
Tony wrote:

> Sharpening should be the very last thing you do.


Depends on how soft the original is. I found if it's TOO soft, when you go
to adjust levels or contrast it can wipe out details. Some need a touch
before you get to work on it (or set slightly sharper in camera/RAW
conversion) and then a final sharpening before printing.


I've also found sharpening looks better done in stages rather than all at
once, just like with resampling.

Try this on the next image you need to sharpen (read this somewhere..)

Set unsharp mask amount to 10-15%, radius to 50, threshold to 0 and apply.
Then do another at 40-80%, radius to 1.5-1.8, theshold to 5-8 and apply and
see what you think. Might need to play with the % depending on the image
and your taste. Each sharpens different parts and really wakes up the edge
contrast. It's a very useful technique.
--

Stacey
 
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