Modern LED technology
Grayscale and colour depth (bits)
A screen that shows beautiful, smooth colour gradients without ugly ‘stripes’ has many grayscale levels. We call that wealth of brightness steps per colour the colour depth, expressed in bits.
Each point of light can not only be on or off, but also shine in very many in-between steps from bright to dark. The more in-between steps, the more softly the colours blend into one another.
If a screen has too few steps, you suddenly see stripes in a sky or a shadow instead of a smooth transition. Many steps = beautiful, smooth images. We call that the colour depth.
The grayscale is the number of brightness levels a screen can show per primary colour (red, green, blue). The colour depth expresses that in bits: 14-bit = 2¹⁴ = 16,384 levels per colour, 16-bit = 2¹⁶ = 65,536 levels per colour.
Why more bits is better
More levels give softer colour transitions and less banding (visible stripes or contours). The difference is especially noticeable in dark scenes and when the screen’s brightness is dimmed: a 14-bit screen then quickly loses effective grayscale, whereas a 16-bit screen retains fine detail even at low brightness. For both indoor and outdoor, at least 14-bit is recommended.
Number of colours
The total number of displayable colours is the number of levels to the third power (red × green × blue). At 16-bit per colour that runs into the trillions of colours. In practice, more colour depth is mainly noticeable as ‘calm’ in the image: no jumps in gradients, even in low light.
Grayscale is realised via pulse-width modulation (PWM): the driver switches each LED on/off very rapidly with a variable duty cycle, so that the eye integrates an average brightness. The bit depth determines the resolution of that brightness scale: 14-bit = 16,384 steps, 16-bit = 65,536 steps per channel.
Low-grayscale loss and refresh
The challenge is that the effective grayscale falls as the overall brightness is reduced (e.g. at night or when dimming): on a 14-bit screen, banding then appears in dark areas, whereas 16-bit retains its detail even at ~10% brightness. High bit depth and a high refresh rate go hand in hand: to render many grayscale levels flawlessly and flicker-free, sufficient refresh and scan capacity is needed. A common practical choice is 14-bit at 3,840 Hz.