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Flutter Shutter (Coded Exposure)

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Flutter Shutter (Coded Exposure)
« on: 07 / May / 2008, 23:47:05 »
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Hi,

I am a researcher at Mitsubishi Eletric Research Labs (Homepage of Amit Agrawal, Mitsubishi Electric Research Labs
(MERL), Cambridge, MA, USA
) working on photography projects. We recently developed the idea of coded exposure for motion deblurring. The idea is to open and close the shutter within a single frame acccording to a binary code as opposed to keeping the shutter open for the entire exposure duration as in a traditional camera. This greatly helps in solving the motion deblurring problem.   

I have implemented it on an off the shelf video camera (e.g. from pointgrey) using "multiple exposure single readout" trigger mechanism and on Canon Powershot using an external ferro-electric shutter placed in front of the lens and sync'd with the flash unit. I was wondering if this could be done on chip on canon cameras using CHDK?  Is it possible to expose the sensor multiple times and do a single readout?

thanks

Amit Agrawal
Research Scientist
Mitsubishi Electric Research Labs (MERL)
Homepage of Amit Agrawal, Mitsubishi Electric Research Labs
(MERL), Cambridge, MA, USA

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Offline DataGhost

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Re: Flutter Shutter (Coded Exposure)
« Reply #1 on: 08 / May / 2008, 03:09:04 »
I don't completely understand what you're trying to achieve, but while porting for my S5 I did some shutter experiments. It's possible to open and close the shutter fairly fast while capture is going on. The resulting image looked like it had been lit by a stroboscope, is that what you mean? You'll still get motion 'blur', though, because the result is basically a couple of very short exposures stacked on top of each other.

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Offline dzsemx

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Re: Flutter Shutter (Coded Exposure)
« Reply #2 on: 08 / May / 2008, 03:30:05 »
the ideea is good and interesant(needs complex calculations :( )
i think that the sensor itself probably can't do multiple exposures with one readout...
he means something like "stroboscope" effect but using the shutter with a predefined binary "rithm" which is used probably in the decoder algorithm to separete image details from motion blur effects...
maybe playing with the mechanical shutter would be the answer:D
@dataghost: how fast is the mech shutter?

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Offline PhyrePhoX

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Re: Flutter Shutter (Coded Exposure)
« Reply #3 on: 08 / May / 2008, 03:32:46 »
i guess he is talking about either Resolving Objects at Higher Resolution from a Single
Motion-Blurred Image: CVPR 2007
or License Plate from Blurred Image.
sounds interesting. i guess highspeed photography isnt an option here since that would require a lot of light.


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Offline dzsemx

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Re: Flutter Shutter (Coded Exposure)
« Reply #4 on: 08 / May / 2008, 03:43:17 »
it requires about 2 times more ligth...

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Offline DataGhost

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Re: Flutter Shutter (Coded Exposure)
« Reply #5 on: 08 / May / 2008, 04:34:00 »
@dataghost: how fast is the mech shutter?
I don't really remember but 'pretty fast'. If I recall correctly, the camera did shut down when switching between open/closed too fast but I haven't quite figured out when yet. I'll have to conduct some more tests with that, maybe later today.

Re: Flutter Shutter (Coded Exposure)
« Reply #6 on: 08 / May / 2008, 17:45:28 »

Hi,

I think what Dataghost does is the closet to what I want.  The net effect is a strobe effect but in exposure. The final photo you will get is a motion blurred image, equivalent to short exposure images stacked on top of each other. Yes, the blur is not removed, but it is converted from a low pass phenomenon in traditional camera to an all pass blur depending on how you open and close the shutter.  50% of the light is lossed and getting a sharp image requires deconvolution based on how you flutterred the shutter in the first place.

I will be interested in getting more details from Dataghost.

thanks







Research Scientist
Mitsubishi Electric Research Labs (MERL)
Homepage of Amit Agrawal, Mitsubishi Electric Research Labs
(MERL), Cambridge, MA, USA

 

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