Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 3:12 am

Using the Unsharp Mask filter is a black art, isn't it?

I found this web article about unsharp mask techniques. Some of it is new to me. I'll be experimenting some new moves with it.

Have a look, you might find it useful.

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Joined: Thu Jun 01, 2000 6:07 pm

RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 3:25 am

I have PSP 7 isnt alot of good for me


RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 3:42 am

I use 'The GIMP for Windows'. I can see a parallel, especially the method using 'layers', which GIMP can do as well. It's just navigating the programme that is different.
Check and see if PSP has a layer function. I'd be surprised if it doesn't.

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RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 6:08 am

One for the bookmarks list I think.

Thanks Gerry,

There are old pilots and there are bold pilots, but there are no old bold pilots
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RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 6:16 am

I found another link dealing with sharpening a while ago. It suggests using the "custom" filter to blur and sharpen at the same time. It's kind of confusing though. Has anyone tried anything like this?

RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 6:32 am

I read that link. Interesting...

It looks like a 'manual' version of applying a filter.
Unsharp masking involves blurring and re-merging the image.
That guy is manually going through the stages step-by-step with
elementary filters.

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RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 6:36 am

Thanks to both of you for forwarding these links!

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RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 7:44 am

Thanks for passing this along!
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RE: Check Out This Unsharp Mask Technique

Fri Feb 01, 2002 7:49 pm

Interesting - another set of techniques totally different to the one I'm currently using! I suspect that these techniques are more appropriate to the production of relatively large images for print as opposed to the smaller images uploaded here.

I think for images, the results produced by the Ultrasharpen plugin are going to be as good as these techniques ... and a lot easier! However, I would advise any PS user to try out the suggestions simply because it will increase your understanding of how PS works.

For anyone who cares, my current sharpening procedure is as follows (PS v.6) please excuse assumed knowledge of PS - I am trying to write an article about image processing which will explain in more detail:

In general, the object of this procedure is to create a sharpening mask which allows you to sharpen only those areas of the image which need sharpening.

1 - Look at each alpha channels in turn and select the one with least noise and clearest line detail - this will usually be the red or green channel. Create a duplicate of this channel

2 - You should now be looking at a grey version of your image. Select filters - stylize - find edges. This should give you a line drawing of your subject. Now invert this so you have a white line drawing on a black background. The white bits are what will be sharpened, the black bits are masked - but the areas to be sharpened need "fattening" and feathering first ...

3 - Select Filters - noise - median. Use a value of 1 for max detail

4 - Select Filters - other - maximum. Fatten up the lines with a value of 1-2

5 - Select Filters - blur - Gaussian blur. This blends the transition between sharpened and hidden areas, and smooths the whole thing. Use the same value as you used in Maximum

Your mask is now complete. Return to the full colour view [CTRL][SHIFT]~

6 - Now apply the mask - go to Aplha channels and [CTRL]select the duplicate channel you created ealier (this contains the mask).

7 - Use Filter - Sharpen - Unsharpmask. Since the mask you created hides any area which does not contain detail, you can be quite agressive in your sharpening without the risk of introducing unwanted graininess or artifacts - try amount 150-200; radius .5 - 1 and threshold 0 (your mask removes the need for threshold)

8 - that's it ... but if your image is grainy overall anyway, you can improve that while you're at it. With the sharpening mask still visible, use Select - inverse to invert the mask. Now the sharpened areas are protected. Use Filters - blur - gaussian blur to smooth grain in those areas with little detail - a value of around .5 - .8 seems to work well, depending on the image.

Please note that I've only been using this technique since Xmas, and am still refining it, so don't look at any of my OLD images for examples ... though I am re-uploading many of these.

One huge advantage of this technique is that you can of course modify the mask with various tools to block out problem areas - eg. jaggy cheat lines.


Colin K. Work, Pixstel

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