Among the parameters of TFT display screens, there are usually different parameters such as color depth 65K colors, 262K colors, and 16.7M colors. What do these three numbers represent?
Before we delve deeper into color depth, let's first explain what a "bit" is. Currently, computers process and store information in binary format. Therefore, any information entering the computer is converted into a combination of 1s and 0s, and this is also how colors are expressed.
1位的色彩深度，在计算机中只能显示0或1，所以能够展现的色彩信息只有两种白色或黑色。当我们将色彩深度提升到2位时，将出现：00、01、10、11，4（2^2）种组合方式，从而产生了相对简单的黑白灰关系。色彩深度达到3位时，将带来8（2^3）种不同的组合方式：000、001、010、011、100、101、110 和 111，黑白灰的过渡将变得更加细致。由此可见，每一次位数的增加，组合方式都会带来翻倍式的上涨。
Let's clarify "65K colors", "262K colors", and "16.7M colors" all at once (they are all terms for color depth/number of colors, not resolution or color gamut):
| Common names | Number of bits per color channel (R/G/B) | Total bits per pixel | Number of displayable colors | Common data formats |
| 65K colors | 5/6/5 positions (R5 G6 B5) | 16-bit | 2¹⁶ = 65,536 | RGB565 |
| 262K colors | 6/6/6 positions (R6 G6 B6) | 18-bit | 2¹⁸ = 262,144 | RGB666 |
| 16.7M colors | 8/8/8 positions (R8 G8 B8) | 24-bit | 2²⁴ = 16,777,216 | RGB888 |
The reason for the extra bit for green is that the human eye is more sensitive to green, and historically, R1G5B6 has been commonly used as a 5-bit pixel format. "16M colors" is often written as "16.7M" or "16.7M," and the exact value is 16.
For delicate transitions like gradients, skin tones, and skies, higher bit depth results in less banding and smoother transitions. For UI/icons/text with noticeable color blocks, the visual difference between 65KB and 262KB/16.7MB is minimal. For photos/videos/medical imaging/in-car video, 16.7MB is recommended (ideally true 8-bit).
当8/16位深度时，单个原始颜色(R/G/B)最大只能表示为(0~2^3)/(0~2^6)，无法满足(0-0xf)的范围，所以显示的颜色范围有限。
When the depth is 24 bits, a pixel is displayed using 24 bits, which is composed of 8 bits of red, 8 bits of green, and 8 bits of blue. Each original color (R/GIB) can be fully displayed (0~0xff), so 24 bits and above are called true color.
When the depth is 32 bits, it is the same as 24 bits, and all colors can be displayed, and an additional transparency value is added.
