Painting with looks

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 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.