Data gathered from a continual data source is converted into an image and represented by a rectilinear grid defining a grid of pixels. Each pixel in each axis unit of one axis is examined in parallel using a graphic processor unit (GPU) to determine whether any pixels exceed a predefined threshold. Those pixels that exceed the threshold are identified as positive return pixels. Within each axis unit groups of positive return pixels are identified based on a first axis epsilon. Adjacent groups of positive return pixels are assembled by merging the axis units based on a second axis epsilon. Groups of positive return pixels grouped together according to the first axis epsilon and the second axis epsilon are classified and reported as a signal.