All luminances that are supposed to be the same should appear the same.
Additional Information:
Luminance uniformity, the variation from the center to the edge of the active area of the display, should not vary more than 50 percent of the center luminance. Unintended luminance variations, within half a degree of arc, calculated from the design viewing distance anywhere on the display, should be less than 50 percent. For an intended uniform luminance, the variation in luminance from the center of the display to the edge or any portion thereof should not vary by more than 50 percent of the center luminance. This measurement is to be made in a dark room.