Apparatus for changing the magnification of video graphics prior to display therefor on a TV screen

摘要

Video magnification apparatus modifies (shrinks or enlarges) video graphic images in a horizontal and vertical direction during a transfer of video graphics data signals from a graphics memory to a television screen. A first magnification modifying device modifies the magnification of a graphic by a vertical magnification factor by generating graphic line address output signals that selectively prevent a transmission of predetermined horizontal lines of the graphic upon the reception of a vertical magnification factor that is less than unity. The first device also causes a transmission of predetermined horizontal lines of the graphic to be selectively repeated upon the reception of a vertical magnification factor that is greater than unity. A second magnification modifying device is responsive to the transmissions of the horizontal lines of the graphic indicated for transmission by the output signals of the first magnification modifying means for modifying the magnification of the graphic in a horizontal direction by a horizontal magnification factor. The second magnification modifying device selects N predetermined pixels of each received X pixel group that are multiplexed into a transmitting X pixel group for transmission in each output signal of the apparatus for a magnification factor equal to or less than unity. Still further, the second device repeats pixels of each received X pixel group a number of times corresponding to an integer magnification factor that is greater than unity for transmission in each output signal of the apparatus.