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Sharpen & Blur?


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Hi Folks,

Just messing about with PS, and was wondering this; Is there any point in doing an unsharp mask and then a guassion blur on top?

I thought that either one would just be the counter of the other...However with a few experements I thought it worked out allright, little bit more structure and detail but without as much noise.

Is this common practice? or was I imagining it, and there was noticeable difference?

Thanks,

Michael

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I often do something similar if I have had a bad night and my subs are a little noisy. I make a slightly 'soft' version of the stacked data and a slightly sharpened version, both from the original data. I then copy the sharp version on top of the soft version and convert it to a 'Hide All' Layer mask. I then use the paint brush to paint in the important detail areas very carefully this maintaining a smooth background but sharp detail where it is required.

As for blurring then sharpening the same data, I can see how this would result in a smoother more satisfying image but I believe that overall detail would be lost.

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Ok cool.

I was doing it with layers, adding one layer with the blur, then erasing like you say the important bits, then flatten, then duplicate again and sharpen but earasing the background. Also I will bring back the opacity a bit to bring back the stars and any other lost detail.

Is there any reason why that would be worse than the methods you both described?

Many thanks,

Michael

Edited by msinclairinork
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Not sure TBH, I think not over doing it is the key. I find using small amounts repeatedly rather a couple of big doses gives you more control. I'd normally use both during processing. Ideally I'll try for smoothing out the background sky & outer parts of the object without it looking 'painted' while sharpening up the detail but without it looking too noisy.

The thing is, process is the 'creative' part of imaging and there's no real incorrect way of doing it, if you get the results you want with a workflow you're happy with then who's to say you're wrong?

Tony..

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Hi Michael,

I may not know much - if anything - about star gazing yet, but I am familiar with PS due to my biggest hobby which is photography.

Steve's method is the preferred way of carrying out 'sharpening' and is none destructive as you are obviously keeping the layers. Until you obviously flatten to create a jpeg for web upload. I assume like most folk in the photography world you save your image with layers in a tiff format and keep that so you can go back to it.

I don't like unsharp mask, finding it too coarse and not as good as this method which you might want to try:

Open your image in RAW

Whilst on the opening 'basic' page adjust the 'Clarity' to about 10

When you have carried out any level or curves adjustments as necessary then right click the 'Background' and 'Duplicate'. I always call this new layer 'Sharpen'

Go to: Filter, High Pass and set a level that will be about 1 - 2 ish. You can see the affect on the gray image if you have preview selected.

You should now have a gray image.

In the layers palate click on blending mode - at the top - and change to 'Overlay' or 'Soft Light'.

This is how I 'sharpen' all of my images and find the results to be much more appealing and with less damage to the original file.

Best regards

Chris

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Any tips on blur to smooth out noise?

Don't - you're crushing detail too. Use the noise reduction tool, this will selectively blur those parts of the image where there is inherently low contrast - the noise isn't as noticeable in high contrast regions, which will retain their crispness.

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Hi Michael,

Assuming you are using blur to smooth out any part of the sky that is not smooth, then gaussian is indeed the same as we would use. It is for example the same method for smoothing the skin on a model.

Unfortunately as I don't have any images of the sky yet I cannot comment on how well it will work.

I am of a mind to think that using something like Nik's Viveza to bring out the 'black' may be good, but again I cannot comment from experience on the sky. It is however the way we would use to bring more colour in the sky by selecting the colour and making it more to our liking or realistic.

Best regards

Chris

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I wouldn't use smart sharpen as it is doing things in the background over which you have little or no control.

A combination of High Pass and UnSharp Mask do the trick every time, use either or both depending on the spatial frequencies you are interested in.

I can't see how USM can be considered too coarse as all three of the variables can be set to zero. How coarse is that?

Dennis

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It's probably academic anyway as I think Michael's version of CS may not have it.

However, "I wouldn't use smart sharpen as it is doing things in the background over which you have little or no control." - you probably have a long history with PS as I do Dennis and were always taught to avoid using the 'kludge' tools like brightness and contrast etc. I think PS has moved on a long way since then and with careful use I think some of these tools are now absolutely excellent. Smart sharpen and shadows/highlights for example are now used in the arsenal of some of the top astro-imagers. Combined with use as 'smart filters' they offer an incredible amount of control.

Just my six-pennorth...

David

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