Rank and File....Horizontal by Vertical.....
TV resolution is measured by rank and file. Therefore a TV picture of 720 x 480 would have 720 dots going across the horizontal axis of the screen, and 480 dots on the vertical axis. These rows of dots would describe rows of pixel points 720 rows of dots from the horizontal, ( these rows would actually run from top to bottom VERTICALLY)! Then the 480 lines of vertical resolution would actually run HORIZONTALLY from side to side of the screen. Basically, what is being described is a matrix. Picture a checkerboard with 720 squares in 1 direction and 480 squares in the other. The total number of "pixels" in the screen would simply be 720 multiplied by 420, which equals 345,600.
In the reproduction of a color picture by a CRT each "pixel" actually consists of 3 apertures in a screen, each being targeted by one of three different color "guns", a red, blue, and a green.