LCD Technology

We’ve already covered the basics of how an LCD works, but not all LCDs are made equal. In this section, we’ll talk about different LCD technologies, with an emphasis on their consequences for the overall display. 

Backlight technology: fluorescent vs. white and RGB LEDs

The light source used in an LCD’s backlight has major consequences for the display’s colour gamut, as well as the uniformity of the display’s luminance and colour.

Older, consumer LCD panels typically use cold-cathode fluorescent light (CCFL) as a backlight source. While inexpensive, this light source tends to produce a relatively narrow colour gamut; perceptually, colours appear somewhat washed out. CCFL panels also have relatively poor display luminance and colour uniformity (<80%), and are prone to hotspotting. 

With the rise of reliable light-emitting diodes (LEDs), many high-end LCDs have begun using LED backlights in order to take advantage of their wider colour gamut, better contrast, and increased energy efficiency. LED backlights may be white, or a mixture of RGB LEDs which produce a broad-spectrum white.

Generally speaking, RGB LEDs produce a wider colour gamut compared to white LEDs. Both types of backlight can be calibrated to achieve uniform display luminance. RGB LED displays can also be factory calibrated to an industry-standard white point, ensuring colour uniformity across the display.

The VIEWPixx /EEG uses a white LED backlight, while the VIEWPixx /3D uses RGD LEDs. Both displays have uniform luminance >95%. The VIEWPixx /EEG has a colour uniformity of approximately 90%. The VIEWPixx /3D is factory calibrated to a D65 industry standard white point, and has >95% colour uniformity across the panel. 

Bit depth

Digital video signals convert colour information into binary steps. A display’s bit depth refers to the number of distinct colour planes that can be transmitted and displayed on the screen. The higher the bit depth, the more planes that can be used and the finer the gradient between colours or grayscale values shown in an image.  

A typical screen uses 8-bit RGB colour, where full white is denoted by an RGB colour triplet of [255, 255, 255]. This means users can adjust between black and white in 256 discrete steps (0-255). By contrast, a 10-bit colour divides the same colour space into 1024 steps, and 12 bits yields 4096 steps. 

Both VIEWPixx monitors use 8-bit colour by default. The VIEWPixx /3D has special colour modes which allow users to show images at up to 10 bits.