CRTs only had 'true blacks' in darkened rooms, otherwise you'd see the phosphors which, especially on older models were more 'gray' or 'greenish' than black. Th

CRTs only had 'true blacks' in darkened rooms, otherwise you'd see the phosphors which, especially on older models were more 'gray' or 'greenish' than black. They also had quite a bit of light bleed from neighbouring image areas due to reflections in the tube front which by necessity had to be thick because it had to be strong enough to a) keep its shape and b) not implode under the near vacuum in the tube.