Patent US 4,047,205

The invention contemplates an improved method and means of electronic-image analysis within a field of raster-scanned subject matter, wherein the volume of an object is evaluated according to its observed light-absorbing properties. The evaluation progresses as successive scans of the object area, at progressively quantized levels of transmitted light, and an appropriate calibration factor is applied to each of the successive object areas thus scanned, so that a volume measurement results from summing the calibration-corrected areas.