Unsharp Mask

[Exfso]

Can anyone give me some idea how to use this feature, a tute or some sort of run through the process. The old fart factor has kicked in and I cant seem to get my head around it.

Thanks in advance.

:ashamed:

[iceman]

You can try this page by Jerry L, astrophotography guru..

http://www.astropix.com/HTML/J_DIGIT/USM.HTM

I haven't tried that technique myself, but it looks good! :)

(ps: moving to techniques forum)

[Exfso]

Thanks Mike, will have a gander.

:)

[Striker]

Your not wrong...it looks great.....cant wait to start doing my crappy noob images.....

[Robby]

That's amazing.... Soo Easy... Just look at what I have done to my boring old M42 image! This process is simply amazing!
Before....
http://www.star-mate.com/DSO/M42_Pro2_normal.jpg
And after....
http://www.star-mate.com/DSO/M42_Pro2_unshape.jpg
Every now & then a wee gem of info comes around. This is one of the better ones!!
Only problem is now I have hours & hours of work ahead of me re-processing all my images...
Thanks Mikey!

[janoskiss]

Sorry Robby, but I like your original image much more. The processed one looks too artificial to my eyes.

[gbeal]

Yep, me too. I have read about this idea before, and while a little application may be OK, the before and afters seal it for me. I like the before. Having said that I WILL get the slave to try it.
Gary

[Robby]

Steve, Gary,
I think that's the idea.!:). The point being, how much more detail is there in the new one. But for pure asthetics it's kinda like the valve arguement for audio.
People like the valve sound cause it is softer and easier on the ear, but it's not actually a "true" acurate representation of the recording. I digress!..
Similary with a softer image, while it might look more pleasant to the eye, that is at the sacrifice of detail. The fact here is that I was stunned at how much extra detail this unshape process extracted. And whats more, for such little effort. I proably over did it for sake of the point, but there you go. Astheticially I'm not sure which one I prefer :confuse3:
Cheers

[[1ponders]]

I'm sitting on the fence on this one. If you split the difference I think you might get it just right. :) Nice to see people playing with ideas. Both are nice shots Robby. I've just notices the unsharp mask has tended to bloat the stars. Wonder if there's a way around that. :confuse3:

[Robby]

Darn fence sitters!!
I used to be indecisive now I'm not sure :D...
Bloating stars are forever a problem for me, just ask Gary! The last thing I need is something to make them worse, and yes this unshape does seem to do that. I got lost in the nebula detail to notice initially...
Cheers

[Striker]

I like the middle one...

hahaha..

Ok I like the first one Gary.....Sorry

[robin]

In Step 5 - 'final levels adjustment', what do they mean when they say ...'go back to the levels dialog & adjust the unsharp-masked image to "reset the black & white points if necessary".'
I get all the other steps no probs, just not sure on that one.

Incidently, I prefer the 1st one Robby......

http://www.astropix.com/HTML/J_DIGIT/USM.HTM

[janoskiss]

They mean that after the previous steps, the intensities may not span the full allowable range (usually 0 to 255), so you might need to readjust. But your image processing software should already do that when you apply an unsharp mask.

Bottom line: This filter subtracts a blurred version of an image from itself. Hence, it is a high pass filter, meaning that it throws out long range variations so that short range ones are emphasised. It may appear that it brings out more detail, but it does so by throwing away information. It mutes the bass so you can better hear the lead. :)

[ballaratdragons]

Robby,

They are both excellent in different ways.

The 1st one is excellent for magazines, posters etc. whereas the 2nd one would be fantastic for a technical book on astonomy/astrophysics as I feel that the 2 pics tell 2 different stories.
No.1 is of the "Oooh-Aaaah!" factor.
No.2 is of the "Wow, look at the structure" factor.

Be proud of both!

[iceman]

I think if you averaged the two it would be the best of both worlds robby..
Good experiment though!

[Robby]

Ok, in the pursuit of the "perfect" image, I have bowed to the pressure.. Here's a shot with quite a bit less of the real unshape mask.
Someone else can try now.....:poke:
http://www.star-mate.com/dso/m42_pro2_half.jpg

[[1ponders]]

Now that's great. The fence sitters win again. How can we not :P And your bloating is lets as well. Any chance of bringing out a bit more colour Robby :)

[gbeal]

Now you're cooking, much better.
I had a bit of time to read while at work yesterday (don't ask), and recall reading something on this bloated subject. I'll dig it out.
Gary

[robin]

Ok...can some one help me.I've followed those steps & the results are certainly looking up.However, this process seems to really dim the finished image.I adjust the levels & brightness/contrast but it still seems really dim & flat.Any suggestions....

[janoskiss]

Robin, how are you trying to do it? In the Gimp (and presumable in Photoshop) there is an "Unsharp Mask" filter to do the job. It's under Filters -> Enhance -> Unsharp Mask.

[Robby]

Steve,
I think robin is trying the real unshape mask as mentioned right at the top of the thread...


Robin,
What program are you using? I used Photoshop, and didn't exactly follow the instructions to the letter. Where the method talks about "apply image", I just used layer subtract. Essentially the same thing, just easier. Try resetting the white point in levels if the final image is too dim, and then stretch the levels some more to acheive a balanced result. Also reducing the brightness of the mask will increase output brightness, but you will have less unshape mask.
Hope this helps
Cheers
Rob

[robin]

I'm doing it the same as the instructions in the link say to.It sharpens the image nicely but always appears much darker,ie: a LOT darker, than the original image. My images are 96 dpi, i take the contrast/brightness to -30 as it says to do. Maybe -30 is too much?


http://www.astropix.com/HTML/J_DIGIT/USM.HTM

[robin]

By the ways guys, I'm using Adobe P.Shop 6. I'm not new to photoshop, been using it 10 years now but I am new to this method of applying an unsharp mask. I'm following the instructions as opposed to going to filters/sharpen/unsharp-mask. Like I said, it sharpens the image REAL nice, but makes it much darker.I'm sure it's only something minor I'm not doing right.