Procedure and device for the automatic correction of skew, of color superimposition, and of image uniformity for television cameras

An apparatus for automatic correction of skew, color superimposition, and image uniformity for a television camera having a scanning means, comprising:

• an optical grid having predetermined homologous patterns defining centers of rotation located at points of intersection of evenly spaced rows and columns;
• an electronic reference grid which is analogous to the optical grid;
• a scanning means for scanning the optical grid;
• means for measuring position errors of the centers of rotations of the patterns of the optical grid in relation to their respective positions on the electronic reference grid;
• first means for computing a first series of correction values for eliminating the measured position errors of centers of rotation;
• second means for computing a second series of correction values for positions of points of the patterns located on vertical straight line segments adjacent opposed sides of the centers of rotation by means of a cubic interpolation computation which takes into account for each pattern, the measured position error of the pattern's center of rotation and the measured position error of the centers of rotation of patterns of the optical grid which are in the pattern's column;
• means for storing the first and second series of correction values;
• and
• means for sending the stored first and second series correction values to the scanning means of the camera in synchronism with the horizontal and vertical scanning operations of the camera.

Procedure for automatic correction of skew, of color superimposition, and of image uniformity for television cameras, by means of an optical grid placed in front of a camera and composed of predetermined homologous patterns whose centers of rotation are located, in accordance with a matrix structure, at points of intersection of evenly-spaced rows and columns, and by means of an electronic reference grid which is analogous to the optical grid, each homologous pattern of the optical and reference grids being scanned during line scanning by the camera using scanning means so as to furnish two video signals, the procedure comprising the steps of:

• measuring position errors of the centers of rotation of the patterns reconstructed by the camera with respect to their respective positions on the electronic reference grid;
• computing a first series of correction values for eliminating the measured position errors of the centers of rotation of patterns requiring correction;
• computing for each pattern requiring correction, a second series of correction values for points of the patterns which have not had a position error measured by a computation, including cubic interpolation, which takes into account for each pattern requiring protection, the measured position error of the center of rotation of a pattern containing points and the measured position errors of the centers of rotation of patterns in proximity to the pattern containing the points;
• storing the first and second series of correction values;
• and
• sending the stored first and second series correction values to the scanning means of the camera in synchronism with the horizontal and vertical scanning operation of the camera to perform the correction.