Picture-in-picture insertion method

摘要

The method involves inserting a picture having a first and a second half frames, into a picture having a first and a second row raster with doubled row frequency. The two halves of the insertion picture are stored in a first and second memory, and are read from it at a doubled line frequency. The phase relation of the main picture to one of the stored insertion picture halves is determined as one of four possible combinations. A localisation signal is produced to determine the actual read out position w.r.t. the overlap position between write-in and read-out of the picture stores. In a first phase relation, the second image memory is read into the first row raster of the main picture, and in a fourth relation the image of the first memory is read into the second row raster of the main picture. In the second condition the first stored half is read into the first main image raster, and in a third condition the second half is read into the second raster. An appropriate line skew is executed in response to the localisation signal for each half image read-out.