Bit Depth,位深

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Bit Depth是一个术语,用来描述图片中用来表达颜色需要用到的bit数。

声音数据也有bit depth概念。


Every color pixel in a digital image is created through some combination of the three primary colors: red, green, and blue. Each primary color is often referred to as a "color channel" and can have any range of intensity values specified by its bit depth. The bit depth for each primary color is termed the "bits per channel." The "bits per pixel" (bpp) refers to the sum of the bits in all three color channels and represents the total colors available at each pixel. Confusion arises frequently with color images because it may be unclear whether a posted number refers to the bits per pixel or bits per channel. Using "bpp" as a suffix helps distinguish these two terms.

bits per channel,每个颜色通道的bit depth。

bits per pixel,每像素点总共的bit depth,bpp。

一般的数码相机的bpp都是24,即每个channel有 8 bit depth。

Bits Per Pixel Number of Colors Available Common Name(s)
1 2 Monochrome
2 4 CGA
4 16 EGA
8 256 VGA
16 65536 XGA, High Color
24 16777216 SVGA, True Color
32 16777216 + Transparency
48 281 Trillion


The human eye can only discern about 10 million different colors, so saving an image in any more than 24 bpp is excessive if the only intended purpose is for viewing. On the other hand, images with more than 24 bpp are still quite useful since they hold up better under post-processing.


HDR10支持10bit bit-depth,DOLBY VISION支持12bit色深。(首先是12 位色深,我们在以前常常听到XX手机或者电视支持1600万色,那是因为在HDTV时期,8位色深最多可以显示1600万种颜色,而近几年,在支持10位色深的HDR10标准下,可以显示10.7 亿种颜色,但杜比视界的12位色深则更进一步,可以显示680亿种颜色,杜比视界相比HDR10能够支持更丰富的色彩显示。)



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