An apparatus and method for continuous synchronization of a pair of independently clocked asynchronous data streams (100, 101) consisting of raster data from independent imaging acquisition systems comprises a means for acquiring individual rasters from a first stream of data. A counter for counting (60) a first total number of received rasters and data merge logic (65) for comparing the first total to a first threshold. A means for acquiring individual rasters from a second stream of data. A means for transferring the first acquired data stream and the second acquired data stream to a composite output when the first total is greater than the first threshold. The method includes adding or subtracting idle pixels from an interline gap.