Removing Camera Shake From a Single Image

[Gareth]

Link: http://people.csail.mit.edu/fergus/research/deblur.html

Camera shake during exposure leads to objectionable image blur and ruins many photographs. Conventional blind deconvolution methods typically assume frequency-domain constraints on images, or overly simplified parametric forms for the motion path during camera shake. Real camera motions can follow convoluted paths, and a spatial domain prior can better maintain visually salient image characteristics. We introduce a method to remove the effects of camera shake from seriously blurred images. The method assumes a uniform camera blur over the image and negligible in-plane camera rotation. In order to estimate the blur from the camera shake, the user must specify an image region without saturation effects. We show results for a variety of digital photographs taken from personal photo collections.

The science bit made my brain ache, but the results look very impressive!

[TheNorm]

Fascinating! I wonder how long it will take to become a standard feature in cameras?

[andygrif]

Looks like they're going to post their source code for all to see, so if that's the case we can expect to see it in things like Photoshop, or as a plug-in pretty soon.

[Jules]

Originally Posted by TheNorm

Fascinating! I wonder how long it will take to become a standard feature in cameras?

I think there is a camera on the market that already allows for this

[altis]

Many camera manufacturers offer this sort of facility. Canon and Nikon have lenses with optical image stabilisation built in. On the other hand Minolta - now part of Sony - have a method of jiggling the sensor round instead. This sounds better if you are swapping lenses but is reportedly slightly inferior. Most other manufacturers offer something similar (although, unfortunately for me, not Fujifilm).

It sounds like a good idea until you realise that it's not perfect after all. It gains you only about 2 stops so you can easily get a similar effect by shooting with a faster 'film' or a faster lens.

If you have some image processing software, like Photoshop or Paint Shop Pro, then you could try an effect called Unsharpen Mask (or USM) which can improve a photograph remarkably.

[Theodoric]

Nothing to do with deconvolution or frequency domains or anything so esoteric, but something I found out the hard way the other week.

I was taking photos at my grandson's birthday party which was in a largish hall. I was trying to be discreet so I stayed a fair distance from the kids. I switched off the flash (which wouldn't have been any good in any case) and used the x3 zoom a fair number of times.

Anyway, I was rather disappointed with a lot of the results - too blurry. A bit of checking suggested that the photos with zoom were the worst. Some searching revealed the probable cause. The aperture without zoom would be much greater than the aperture with zoom so that the exposure in the former case would be less and any camera shake avoided.

With hindsight what I should have done was not use the zoom and subsequently blow up the images on my PC - it's a 7MPixel camera so there should be enough resolution to spare to do this.

Ah, well, I'll know in future!

[bmxbandit]

interesting results, but still looks a long way away from being a commercial feature.

i'll wait for mems gyroscopes to get better, which have the potential to remove any jitter entirely.

[TheNorm]

What an amazing idea!

[andygrif]

Originally Posted by altis

Many camera manufacturers offer this sort of facility. Canon and Nikon have lenses with optical image stabilisation built in.

They do indeed, but they are very expensive, as the technology to process a stabilised image is very sophisticated, involving one of the lens elements to be effectively 'floating' and is a hardware based solution rather than a post processing option via software.

Originally Posted by altis

It sounds like a good idea until you realise that it's not perfect after all. It gains you only about 2 stops so you can easily get a similar effect by shooting with a faster 'film' or a faster lens.

Two stops of light is extremely significant - it's the difference between a shutter speed of 1/60th second and 1/250th second or ISO200 vs ISO800. Also, you tend to find that most IS lenses offer a wide aperture anyway such as f/2.8 as well as generally superiour optical performance. Lenses of f/1.4 or f/1 tend to be very expensive.

Originally Posted by altis

If you have some image processing software, like Photoshop or Paint Shop Pro, then you could try an effect called Unsharpen Mask (or USM) which can improve a photograph remarkably.

USM can make a bad photo slightly better, but if you have a blurred photo, it will not help it too much. There's a new sharpening tool in Photoshop CS2 called Smart Sharpen, which works better than USM on most things, but still won't rescue a blurry image.

Originally Posted by Theodoric

Anyway, I was rather disappointed with a lot of the results - too blurry. A bit of checking suggested that the photos with zoom were the worst. Some searching revealed the probable cause. The aperture without zoom would be much greater than the aperture with zoom so that the exposure in the former case would be less and any camera shake avoided.

The aperture with or without zoom should not really change much, if at all. When zooming the lens you are magnifying the image, thus magnifying any shake (even a tiny one) by the same factor. There is a rule of thumb for using zoom, use a shutter speed faster than the focal length. I appreciate that determining a focal length equivalent on a compact is not always easy, but for example if your focal length was 200mm you should use a shutter speed of 1/200th or faster. If you're using 60mm then 1/60th. But don't generally go below 1/60th for any handheld shot without IS.

Also, another factor is that you're photographic subjects that are running around like possessed things! They are moving quickly, so your shutter speed needs to do the same, or the results will blur, even if you've not got any camera shake. So increasing the ISO (film speed, light sensitivity) whilst adding more grain, will allow for faster shutter speeds needed for low-light zoom photos. Also, a large aperture (small f/ stop number) allows more light to reach the sensor, resulting in shorter exposure times, but a limited depth of field - so if you're focussing on the rwrong thing then that will result in blurring too.

Hope this helps.

[altis]

Okay, it costs more than with software but OIS doesn't have to be horrendously expensive. Pentax's new DSLR, the K100D, does OIS with a wobbling CCD so it will stabilise any K-mount lens. More details here:
http://www.pentaxslr.com/home
...and here:
http://www.pentaximaging.com/product...n--digital_slr

...and is available, including the 18-55mm kit lens, for £382+VA T at Pixmania:
http://www.pixmania-pro.co.uk/uk/uk/...-18-55-mm.html

[Flobajob]

Loads of camera's have OIS, even my phone claims to have it (though I'm not sure of how effective it is). The Panasonic range of compacts have it, the budget DSLR from Konica Minolta, R.I.P., has it.

[andygrif]

Originally Posted by altis

Okay, it costs more than with software but OIS doesn't have to be horrendously expensive. Pentax's new DSLR, the K100D, does OIS with a wobbling CCD so it will stabilise any K-mount lens. More details here:
http://www.pentaxslr.com/home
...and here:
http://www.pentaximaging.com/product...n--digital_slr

...and is available, including the 18-55mm kit lens, for £382+VA T at Pixmania:
http://www.pixmania-pro.co.uk/uk/uk/...-18-55-mm.html

A wobbly sensor does help, but not considered to be as effective as the more complex in-lens systems with the floating element. But still better than no IS if you're needing that function.

Of course the BIG advantage of having the IS built into the sensor is that every lens you use with the camera will benefit from stabilisation, whereas if you're a serious user you've probably got five or six lenses and buying five or six IS lenses can cause divorce!

Originally Posted by Flobajob

Loads of camera's have OIS, even my phone claims to have it (though I'm not sure of how effective it is). The Panasonic range of compacts have it, the budget DSLR from Konica Minolta, R.I.P., has it.

My cameraphone also says its got IS...but it's not OIS, it's digital IS which is basically just a clever bit of processing - but again not close to OIS. AFAIK the new Sony SLR (the old Konica) also has the floating sensor like the Pentax that altis was talking about.

[Taf]

Fuzzy logic used to be used to prevent camera shake blurring....

[TheNorm]

Originally Posted by Taf

Fuzzy logic used to be used to prevent camera shake blurring....

That's a joke, yes? A pun. Or is it?