Abstract: An improved color picture tube includes a shadow mask and a dot screen, wherein the mask has two long sides and two short sides. The long sides of the mask parallel a central major axis of the mask, and the short sides parallel a central minor axis of the mask. The mask includes an array of apertures. The improvement comprises each of the shadow mask apertures being substantially rectangular with four sides. Two of the aperture sides approximately parallel the major axis and establish aperture height. The other two aperture sides approximately parallel the minor axis and establish aperture width The widths and heights of the apertures increase at a first rate and a second rate, respectively, from the center to the sides of the mask, along the major axis; and the widths and heights of the apertures increase at a third rate and a fourth rate, respectively, from the center to the top and bottom of the mask, along the minor axis.