“像素”（Pixel） 是由 Picture 和 Element这两个单词组成的，是用来计算数码影像的最基本单位，如同摄影的相片一样，数码影像也具有连续性的浓淡阶调，我们若把影像放大数倍，会发现这些连续色调其实是由许多色彩相近的小方点所组成，这些小方点就是构成影像的最小单位“像素”（Pixel）。
单一像素长与宽的比例不见得是正方形（1：1），依照不同的系统尚有“1.45：1”以及“0.97：1”的比例，每一个像素都有一个对应的色板。
|
1bit＝2色 |
7bit＝128色 |
|
4bit＝16色 |
8bit＝256色 |
|
5bit＝32色 |
16bit＝32768色 |
|
6bit＝64色 |
24bit＝16777216色 |
也就是说，越高位的像素，其拥有的色板也就越丰富，越能表达颜色的真实感。
Pixel
Short for Picture Element, a pixel is a single point in a graphic image. Graphics monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels are so close together that they appear connected.
The number of bits used to represent each pixel determines how many colors or shades of gray can be displayed. For example, in 8-bit color mode, the color monitor uses 8 bits for each pixel, making it possible to display 2 to the 8th power (256) different colors or shades of gray.
On color monitors, each pixel is actually composed of three dots -- a red, a blue, and a green one. Ideally, the three dots should all converge at the same point, but all monitors have some convergence error that can make color pixels appear fuzzy.
The quality of a display system largely depends on its resolution, how many pixels it can display, and how many bits are used to represent each pixel. VGA systems display 640 by 480, or about 300,000 pixels. In contrast, SVGA systems display 800 by 600, or 480,000 pixels. True Color systems use 24 bits per pixel, allowing them to display more than 16 million different colors.
