Abstract: Data for providing spatial and shading error correction signals during the operating mode of a television camera, are taken from a two dimensional array of correction points distributed across a television image during the camera setup mode and are stored as 8 bit words. The error correction signals extend smoothly (linearly) between the correction points. The smoothing is performed by selectively interpolating selected reference points on each video line to provide values which vary smoothly from one row of correction points to the next. A vertical interpolation circuit performs a vertical interpolation on a line-by-line basis, by adding signals produced by a multiplying D/A converter when loaded with the two values to be interpolated and weighted by factors related to the distance from each correction point.

Abstract: The conventional vertical drive sawtooth is modified, during the camera setup mode, to halve the slope thereof for a given field time interval, or intervals, and to double the slope for the remaining field time interval. It follows that the speed of vertical scan is halved and doubled respectively, in the corresponding field time intervals. In the interval of double scan speed, blooming occurs and twice the usual beam current is required to successfully discharge the picture. Thus when the beam set circuit is in operation as during the setup mode, the beam current is increased until the blooming existing in the double scan speed interval just subsides. The beam current has then been set at 200% of typical beam level.