Information Technology Reference
In-Depth Information
Figure 3.63:
Image-stabilizing cameras sense shake using a pair of orthogonal gyros which sense movement of
the optical axis.
Figure 3.64:
Image-stabilizing cameras. (a) The image is stabilized optically prior to the CCD sensors. (b) The
CCD output contains image shake, but this is opposed by the action of a DVE configured to shift the image under
control of the gyro inputs.
Alternatively, the camera can contain a DVE where the vectors from the gyroscopes cause the CCD camera output
to be shifted horizontally or vertically so that the image remains stable. This approach is commonly used in
consumer camcorders.
A great number of video recordings and films already exist in which there is camera shake. Film also suffers from
weave in the telecine machine. In this case the above solutions are inappropriate and a suitable signal processor is
required.
Figure 3.65
shows that motion compensation can be used. If a motion estimator is arranged to find the
motion between a series of pictures, camera shake will add a fixed component in each picture to the genuine object
motions. This can be used to compute the optic flow axis of the camera, independently of the objects portrayed.
