The PUTMAP function writes the given array of bytes into a given rectangular area of the bigimage, irrespective of lane boundaries. It has to be given the bigimage descriptor, the starting pixel count in X and Y, and the finishing pixel count in X and Y. No interpretation or type conversion is provided. It is left to the application program to ensure the inserted bytes match the bigimage type correctly as I2S or whatever.
Note that this routine can only overwrite EXISTING pixel values.