摘要 |
An original density picture is produced from an input color picture, a pixel in a background area is designated and the density of the designated pixel is used as a reference density. A background density picture is produced by processing the original density picture with the reference density. Or a background density picture is produced by filtering the original density picture through low pass filter means. By subtracting the background density picture from the original density picture, a characteristic figure superimposed on a background scenery is extracted.
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