Contrast on a LED screen
Contrast is an essential parameter of color rendering on a LED screen. Contrast is the difference in visual properties that makes an object (or its representation in an image) distinguishable from other objects and the background. In case of a LED screen if the black color is not really “black”, then the human eye will not distinguish the details on dark image areas – they will merge will less dark areas. Black color on a LED screen has nothing to do with performance of an LED – black background is created by materials used manufacture a LED screen.
Problems may result from reflection of sunlight from LED screen surface: in this case when all LEDs are switched off the screen surface may appear whitish in color. This effect is caused by white LED epoxy lens, shiny black surface of protective plastic between LEDs, incorrect position of protective louvers or even light-color LED padding. In general, the better is the matte dark surface of an LED screen the higher is the contrast and image quality.
Number of colors and cost of a LED screen
Number of colors on a LED screen may only be increased by:
using “intellectual” IC drivers;
increasing PWM frequency;
reducing refresh frequency.
Brightness, color rendering and contrast of a LED screen: Conclusions
The more brightness levels are generated by PWM, the easier it is to fine-tune LED screen to accurate color rendering.
Color adjustment must be available on all control system components: from software to LED drivers. Theoretically calculated number of colors runs into billions and trillions. However, the system is not always capable of displaying all these hues.
Image quality is affected by components used for manufacturing LED screen surface: it should be as dark and matte as possible.