What are web safe colors?

Web safe color has no concept for most people who write programs. Of course, web safe color itself is a historical issue, and there is no need to discuss it much today. . The introduction of web safe colors here is just to help friends who are still Google "is web safe color still important" (the useful information searched on Google is indeed much better than Baidu) to understand what web safe colors are. 216 web-safe colors are a thing of the past.

Why use web safety colors?

The opposite of security is of course unsafe. When you write a paper of tens of thousands of words in Word on Mac and take it to the copy shop to print and find that the TMD is all garbled, you will Can deeply appreciate the wonderful use of web security colors.

The so-called web safe colors refer to colors that display the same effect on different platforms. For example, it originally displays dark red under Mac, but it may be rendered into other colors under Windows.

In short, using web safe colors can ensure that the effects on different platforms are consistent with expectations.

Why does the web security color appear?

You can always avoid dithering colors on a 256-color computer system - "The Definitive Guide to CSS"

The principle of displaying different colors on the monitor is different combinations of red, green and blue. In a CRT computer monitor, there are three "guns" that emit three kinds of light: red, green, and blue respectively. By controlling the intensity of different light beams, various colors are formed.

Before talking about the emergence of web safe colors, let’s popularize the representation of colors:

There are many ways to express colors, please refer to Wikipedia for details.

Here we only explain the hexadecimal representation method. If we need white, the usual writing method is #FFFFFF or (#FFF). Use two hexadecimal digits to represent red (green, blue) and convert it to The base 10 system is (255,255,255).

Why is it 255?

How many colors a computer can represent depends on how many bits are used for color storage. If 24 bits are used, it is what we often call true color. There can be a total of 256*256*256 different colors. .

Let’s talk about Dithering

Old-fashioned computers are limited by the size of the video memory. Generally, they only have 4 to 16 bits of space to store colors, so they can only display a maximum of 256 colors. In order to display more For color, the technology of dithering is proposed. Dithering interleaves different colors to produce the visual effect of new colors, as shown below:

But the color matching of different platforms Boards are different, which means dithering techniques may have different effects.

Speaking of this, do you understand? The most basic 256 colors can actually be used as safe colors. However, because some platforms only support 216 colors (can someone explain this), these 216 colors Officially what we call safe colors.

Safe colors are all multiples of RGB value 51, so rgb(0,204,153) and rgb(255,0,102) are both safe colors.

Why is it a multiple of 51? See the structure of the palette under different platforms in the picture below:

Now it is Almost no computers still use 256 colors, so go ahead and use web safe color.

Recommended tutorial: "CSS Tutorial"

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