Painting with Looks: Photographic images from video using
quantimetric processing
Steve Mann, Corey Manders, and James Fung
University of Toronto
Department of Electrical and Computer Engineering
ABSTRACT
When we ask the fundamental question ``What does a camera measure?'',
we arrive at the concept of quantimetric imaging, which uses a new quantimetric
unit, $q$, characteristic of a particular camera (e.g. each kind of
camera defines its own quantimetric unit $q$ based on its spectral
response, etc.).
Fluctuations in interframe exposures, along a sequence of images,
give rise to a {\em comparametric} relationship between successive
pairs of images. This allows us to estimate the response function of
the camera (to derive the quantimetric unit $q$) as well as the
relative differences in exposure.
A new method of video image processing that exploits
multiple differently exposed pictures (frames of the video sequence)
of overlapping subject matter is thus possible.
The method may be used
whenever a video camera having automatic exposure
captures multiple frames of video with the same subject matter appearing
in regions of overlap between at least some of the successive video frames.
Since almost all cameras have an automatic exposure feature,
typically center weighted,
when a light object falls in the center of the frame the exposure is
automatically decreased,
whereas the exposure is automatically increased when the camera swings
around to point at a darker object. Such fluctuations in gain may be
used to estimate the camera's response function, to estimate exposure
differences, to do quantimetric processing, as well as to
obtain images having both extended dynamic range and extended
dynamic domain.
keywords
video, image processing, comparametrics, comparametric equations,
multiple exposures
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