|Choosing the Best LCD Panel Technology|
|Articles - Featured Guides|
|Written by Olin Coles, David Ramsey & Vito Cassisi|
|Wednesday, 15 September 2010|
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Bit depth is the number of bits used to 'describe' the color of a particular pixel, also known as 'bits per pixel'. A bit depth of 24-bits is often referred to as 'truecolor', and is accepted as a high quality representation of colors within a given RGB gamut. 24-bits allows for 224 colors to be represented (that's 16,777,216 different colors)! As you'd expect, bits are just data, and when it comes to color, humans can't see data unless it's first converted to light via a monitor such as a LCD panel. Not all panels are created equal, however.
As we've discussed previously, there are many different panel types, including but not limited to TN, VA and IPS. Twisted Nematic panels are regarded as the lowest-grade of the lot, and for good reason. Generally, a TN panel can only produce 6-bits of color per RGB subpixel. That is, 6-bits for red, 6-bits for green and 6-bits for blue. When combined, this gives a total of 218 (262,144) unique colors, which is equivalent to 18-bits per pixel. Clearly this is vastly inferior to the 16+ million colors of an 8-bit panel which can display 8-bits per subpixel for a total of 24-bit truecolor. But surely a panel with 64x fewer colors would look horrible? This is where the trickery that is dithering comes into play.
Dithering is often used on 6-bit panels to produce truecolor images. Dithering can produce extra colors by tricking the human eye via processes such as flickering between two colors to produce an intermediate color, and using a halftone-esque technique such as a checkerboard pattern. Variations of the latter are often used.
But how does one determine the bits per subpixel of a given panel? Well, it's not easy, since all modern panels claim to produce millions of colors. Fortunately, there are ways to spot the difference, including:
Although 6-bit panels sound dodgy, they do have a speed advantage for fast-paced games and movies. Dithering tends to do well in modern LCD monitors, such that trying to distinguish between a 6-bit and 8-bit panel can be difficult without direct comparison. The main reason for purchasing an 8-bit panel is color accuracy when working with graphic software, so unless your line of work is color sensitive, the price and response time may be off-putting.