a color cathode ray tube includes a generally rectangular phosphor screen having a plurality of phosphor pixel line - trios each formed of three color phosphor pixels arranged in a line and a black matrix of opaque material having holes for defining areas of the phosphor pixels which are viewed through a panel , a shadow mask having a large number of mask apertures for color selection , and an electron gun . a distribution in area of center phosphor pixels of the phosphor pixel line - trios has sharp decreases , going from a center of the phosphor screen toward a periphery of the phosphor screen , in the vicinity of at least one of top and bottom sides and right and left sides , of a rectangular useful display area of the phosphor screen .