11/10/2017
Shape from defocus • Basic idea of shape from defocus
• If a point is located on the focal plane, then all the rays (green lines) from this this point will converge to a single sensor point and the image will appear sharp • If a point is not located on the focal plane, then all the rays (blue lines) will reach multiple image sensor points and result in a blurred image (the blurred region is called circle of confusion)
Shape from defocus • Basic idea of shape from defocus
• If a point is not located on the focal plane, then all the rays (blue lines) will reach multiple image sensor points and result in a blurred image (the blurred region is called circle of confusion) • The diameter of the circle of confusion is:
Shape from defocus • Basic idea of shape from defocus
• • c can be measured by the width of an edge
Shape from defocus • Basic idea of shape from defocus
• How to mathematically measure blurness
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11/10/2017
Shape from defocus
Shape from defocus
• Example
• Let’s apply the state‐of‐the‐art shape from defocus method on MIT dataset
Shape from defocus
Shape from defocus
• Example
• Let’s apply the state‐of‐the‐art shape from defocus method on MIT dataset
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11/10/2017
Shape from defocus
Shape from defocus
• Let’s apply the state‐of‐the‐art shape from defocus method on MIT dataset
• Apply the state‐of‐the‐art shape from defocus method on NYU dataset
Shape from defocus
Shape from defocus
• We can see that shape from defocus is difficult to detect subtle depth change
• Apply the state‐of‐the‐art shape from defocus method on NYU dataset
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11/10/2017
Shape from defocus
Shape from defocus
• It looks like images in NYU dataset are not strictly focused at some point
• Successful cases:
Shape from defocus
Shape from defocus
• Successful cases:
• The preliminary results show that • The shape from defocus method works when there are significant variations of blurriness in the image • It works better with camera with small depth of field • When depth change is small, the change of blurriness is so small that we can’t even detect it from the image. Hence blurriness is not a strong cue for subtle depth change
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