Minimally Distinct Border
In an exactly abutting pair of spatially uniform colored regions, if one of the regions is varied in radiance until the border between the regions is least conspicuous to a human observer, that border becomes a minimally distinct border (MDB) and is seen as having maximal blur and minimal contrast. The term MDB is used both for the border itself and for the psychophysical method used to derive it.
The minimally distinct border was first reported by Boynton and Kaiser  in connection with psychophysical experiments. From the beginning, it was realized that the condition of MDB occurs when the two abutting regions have the same luminance. Hence, the condition of MDB is best understood in terms of the properties of luminance. (See next section.)
However, the history of the MDB is not just about luminance [2, 3]. The MDB was first used in an attempt to quantify complete color differences regardless of their size. Previously, whereas small color...
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