OLED has inherent excellent performance in terms of contrast. OLED display has the ability to turn on and off pixels independently at the pixel level. When presenting a black image, the pixel-point light sources can be completely turned off, thus achieving an absolute black display effect.
The contrast of digitally-driven OLED microdisplays has an advantage. Each pixel in Micro-OLED requires a very small amount of current. For some low-brightness pixels at adjacent luminance levels, the current differences are often very subtle. How to make these similar but not identical low-brightness pixels emit the correct light has become a difficult problem.
Analog driving controls the current by adjusting the voltage of each pixel-driving transistor. This subtle current difference is difficult for analog signals to distinguish accurately, which may lead to the situation in image display that similar low-brightness pixels are wrongly assigned the same or indistinguishable luminance values, and the image may appear to have a relatively low contrast. Even if there is a difference in brightness between the brightest and darkest areas, because of the lack of sufficient and delicate luminance levels, the transition between light and dark in the image seems rather "abrupt". For example, some subtle shadows and object contours in the dark part of the image cannot be presented accurately. This overall "flattening" of the dark part and the reduction of details will directly affect the contrast performance of the image.
Digital driving controls the luminance by adjusting the ratio of the on-time to the off-time of each pixel. This control method does not rely on the distinction of tiny current differences. For pixels at various luminance levels in silicon OLED microdisplays, no matter how small the required current is, digital driving can accurately adjust the ratio of the on-time to the off-time of pixels through digital signals to restore accurate luminance levels. Even for low-brightness pixels, the transition is still step-by-step with clear details. This helps to enhance the difference between the dark and bright parts of the image, making the contrast of the entire picture more realistic and intense, and improving the contrast performance!
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