Scan converter system

Claim 1

Apparatus for deriving from data samples at the intersections of radial lines of a sector with arcs having a spacing s and the same origin as the radial lines a final interpolated data value to be used at display points within said sector, said display points being arranged in rows and columns, the said origin having a given location with respect to said rows and columns, there being a separation K x between the columns and a separation K y betwken the rows, an input to which data samples may be applied, memory means coupled to said input for storing at least three radial lines of the said data samples, selection means identifying a display point and deriving at least four data samples, at least two from one radial line and at least two from another radial line, the identified display point and the data samples being related in that the locations of said at least four data samples define an area containing the identified display point, the said apparatus comprising means for deriving a first intermediate interpolated data value from two of said data samples on one of said radial lines at the intersection of said radial line with a row of display points including the identified display point for which a final interpolated data value is sought, means for deriving a second intermediate interpolated data value from two of said data samples on said another radial line at the intersection of said another radial line and said row of display points including said identified display point for which a final interpolated data value is sought, means for deriving a signal representing the angular position of said identified display point with respect to said radial lines, and means for interpolating said first and second intermediate interpolated data values in response to said signal representing the angular position of said identified display point so as to derive a final interpolated data value at said angular position.