UKC

Hi all. I'm trying to unblur a section of a picture. Now, i know it isn't really possible to fully fix an image when it's blurred, but since it's only a small section of the picture that is so i'm trying to simply make it less obvious so as to go unnoticed.

I've been experimenting, and so far i got not too bad results by Gaussian blurring to remove the motion blur and then applying an unsharp mask in an attempt to remove the gaussian blur. Problem is that the gaussian remains noticeable unless i sharpen it so much as to become very noisy.
Also tried using a lens blur instead of the Gaussian to try to pass it off as DOF, but unfortunately that part of the picture is not in a field that should be out, so it gives it an unnatural feel.

Are there any techniques or tricks out there that can be used for this? Any ideas as to what can be done?

Cheers

In reply to Mr Lopez: Don't shake the camera while taking the picture ?


*Gets Coat*

In reply to Mr Lopez: Hmm, got me stumped. Best I could think of is to see if you could get a replacement image of the bit you want to unblur (either by retaking if it's local to you - but then presumably you could just retake the whole thing? - or finding something similar to replace it with) and then cloning it in. Can't imagine it would be easy to make everything match up though. Sure there'll be plenty of others along who know all the tricks and tools that PS and other packages have to offer though.

In reply to Mr Lopez:

It is theoretically possible, but difficult to do properly. You need to perform a process called "deconvolution", which reverses the blur operation.

To do this you need to get a linear image (no curves or gamma correction), and the exact shape of the motion blur.

Then you perform a couple of fourier transforms, a bunch of complex divisions and a couple more fourier transforms and if you are lucky you will have something approximating a clean image.

As far as I know very few paint programs offer this because:

- you get detail back at the cost of dynamic range/colour precision. It probably looks better blurred.
- you need to know the exact shape of the blur. Get it wrong and you get crazy ringing artifacts everywhere.
- It is complicated, and the other problems make it not worth the effort.

On the other hand it's the basic technique used to fix the images from Hubble when it had a wonky mirror.

In reply to davidbeynon:

Yes, i tried a bunch of these programs and they don't seem to work in anything other than the sample images they use to make you download it...

It depends heavily in the detail/contrast/noise of the image, and so the programs are only useful in fairly limited circumstances, sometimes impressively well though, such as here http://refocus-it.sourceforge.net/

In reply to What Goes Up:

Not much chance for either. One is simply not possible, the other one is 'cheating'.

In reply to Mr Lopez:

Have you try the smart sharpen tool (>filters>sharpen)? It gives you options to remove motion blur and let you do all sorts of fine tuning in advanced mode. Not tried it myself though.

Otherwise there might be other ways to treat the image and make the unintended blurring look less dominant (without too make faking). Might be helpful if you can give us more information or show us the image.

In reply to jamestheyip:

Just had a play with the smart sharpen tool. I think it's more aimed at camera shake rather than objects moving in the frame though. There's an angle adjuster which might be useful. You might need to select the sharpen area with feather tool to make it look more natural.

In reply to jamestheyip:

What software is that on? If it's photoshop it must be a later version to the CS i'm running, as the sharpen filter doesn't have any options.

In reply to Mr Lopez:

I have it on CS2. Must be a new feature added in that version then.

Perhaps try this?

http://blip.tv/file/374045

In reply to jamestheyip:

Nice one. After a very brief play it seems to work quite well. I'll experiment a bit more and see how it goes.

Thanks for that.

In reply to jamestheyip:

Just an update for anyone interested that the emboss filter technique has worked beautifully.
Combined with a mask layer, some manually edge sharpening and some gaussian/blur tool/sharpen retouches mainly to get rid of the noise generated has made it nearly unnoticeable.

Thanks for the tip!

In reply to Mr Lopez: Sounds interesting, can we see a before and after pic? =o)