Processes and apparatuses for characterizing the spatial relationship of two displayed objects. Differences between pairs of coordinates of the two objects are generated. The differences are sequentially stored as binary values in the lower half of a data register and shifted left one bit to preserve the most significant bit of each difference in the upper half of the register. The spatial relationship between the two objects is characterized by accessing a lookup table using a table index, where the table index is the shifted bits in the register's upper half (i.e., a value corresponding to the MSBs of the coordinate differences).
There is provided with a video display apparatus comprising: a receiving unit configured to receive a composite video image generated from a plurality of video sources; a display unit configured to display the received composite video image; an area manager configured to store area information pieces; a position specification unit configured to specify a position on the composite video image; an area selection unit configured to select an area information piece from the area information pieces; an area display unit configured to provide information indicating the area represented by the selected area information piece to the display unit so as to superpose the information on the displayed composite video image; an area change unit configured to change the information; an area information update unit configured to update the selected area information piece; and a transmission unit configured to transmit an update control signal containing the area information piece after update.
