stabilization-22apr10-150dpi-med

stabilization-22apr10-150dpi-med - Optical image...

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Optical image stabilization (IS) CS 178, Spring 2010 Marc Levoy Computer Science Department Stanford University
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! Marc Levoy Outline ! what are the causes of camera shake? how can you avoid it (without having an IS system) treating camera shake as a 2D convolution of the image ! image stabilization systems mechanical optical electronic (i.e. digital) ! optical image stabilization lens shift sensor shift how much does stabilization help? 2
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! Marc Levoy ! primary cause is neuro-muscular tremor period = 8-12 cycles per second amplitude increases with muscular contraction, fatigue, emotional state, cold temperatures, stimulants, time of day ! secondary causes SLR mirror and shutter lightweight tripod wind and other sources of vibration ! exacerbating factors long focal length lenses long exposure time heavy camera, light camera, poor grip, poking at the shutter 3
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! Marc Levoy Examples 4 (wildsight.co.uk) (samgraphicdesign.com)
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! Marc Levoy Camera shake as convolution ! camera shake is camera translation (3 d.o.f.) + rotation (3 d.o.f.) ! for sufFciently distant objects, camera translation can be ignored ! camera rolling (around optical axis) is seldom a problem* ! ! these motions can be approximated as 2D translation of the scene 5 *recent research suggests otherwise [Levin 2009]
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! Marc Levoy Rotation around center of perspective can be approximated as 2D translation of the image 6 as rotation as translation sensor rotates down, features move up effect is nearly the same
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Marc Levoy Camera shake as convolution ! camera shake is camera translation (3 d.o.f.) + rotation (3 d.o.f.) ! for sufFciently distant objects, camera translation can be ignored ! camera rolling (around optical axis) is seldom a problem ! ! these motions can be approximated as 2D translation of the scene ! their effect over time is a 2D convolution of the scene by a Flter function equal to the translation path 7 scene f ( x , y ) ! = f
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This document was uploaded on 12/06/2011.

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stabilization-22apr10-150dpi-med - Optical image...

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