216 Web安全色

HTML#000000 RGB000

HTML#000033 RGB0051

HTML#000066 RGB00102

HTML#000099 RGB00153

HTML#0000CC RGB00204

HTML#0000FF RGB00255

HTML#003300 RGB0510

HTML#003333 RGB05151

HTML#003366 RGB051102

HTML#003399 RGB051153

HTML#0033CC RGB051204

HTML#0033FF RGB051255

HTML#006600 RGB01020

HTML#006633 RGB010251

HTML#006666 RGB0102102

HTML#006699 RGB0102153

HTML#0066CC RGB0102204

HTML#0066FF RGB0102255

HTML#009900 RGB01530

HTML#009933 RGB015351

HTML#009966 RGB0153102

HTML#009999 RGB0153153

HTML#0099CC RGB0153204

HTML#0099FF RGB0153255

HTML#00CC00 RGB02040

HTML#00CC33 RGB020451

HTML#00CC66 RGB0204102

HTML#00CC99 RGB0204153

HTML#00CCCC RGB0204204

HTML#00CCFF RGB0204255

HTML#00FF00 RGB02550

HTML#00FF33 RGB025551

HTML#00FF66 RGB0255102

HTML#00FF99 RGB0255153

HTML#00FFCC RGB0255204

HTML#00FFFF RGB0255255

HTML#330000 RGB5100

HTML#330033 RGB51051

HTML#330066 RGB510102

HTML#330099 RGB510153

HTML#3300CC RGB510204

HTML#3300FF RGB510255

HTML#333300 RGB51510

HTML#333333 RGB515151

HTML#333366 RGB5151102

HTML#333399 RGB5151153

HTML#3333CC RGB5151204

HTML#3333FF RGB5151255

HTML#336600 RGB511020

HTML#336633 RGB5110251

HTML#336666 RGB51102102

HTML#336699 RGB51102153

HTML#3366CC RGB51102204

HTML#3366FF RGB51102255

HTML#339900 RGB511530

HTML#339933 RGB5115351

HTML#339966 RGB51153102

HTML#339999 RGB51153153

HTML#3399CC RGB51153204

HTML#3399FF RGB51153255

HTML#33CC00 RGB512040

HTML#33CC33 RGB5120451

HTML#33CC66 RGB51204102

HTML#33CC99 RGB51204153

HTML#33CCCC RGB51204204

HTML#33CCFF RGB51204255

HTML#33FF00 RGB512550

HTML#33FF33 RGB5125551

HTML#33FF66 RGB51255102

HTML#33FF99 RGB51255153

HTML#33FFCC RGB51255204

HTML#33FFFF RGB51255255

HTML#660000 RGB10200

HTML#660033 RGB102051

HTML#660066 RGB1020102

HTML#660099 RGB1020153

HTML#6600CC RGB1020204

HTML#6600FF RGB1020255

HTML#663300 RGB102510

HTML#663333 RGB1025151

HTML#663366 RGB10251102

HTML#663399 RGB10251153

HTML#6633CC RGB10251204

HTML#6633FF RGB10251255

HTML#666600 RGB1021020

HTML#666633 RGB10210251

HTML#666666 RGB102102102

HTML#666699 RGB102102153

HTML#6666CC RGB102102204

HTML#6666FF RGB102102255

HTML#669900 RGB1021530

HTML#669933 RGB10215351

HTML#669966 RGB102153102

HTML#669999 RGB102153153

HTML#6699CC RGB102153204

HTML#6699FF RGB102153255

HTML#66CC00 RGB1022040

HTML#66CC33 RGB10220451

HTML#66CC66 RGB102204102

HTML#66CC99 RGB102204153

HTML#66CCCC RGB102204204

HTML#66CCFF RGB102204255

HTML#66FF00 RGB1022550

HTML#66FF33 RGB10225551

HTML#66FF66 RGB102255102

HTML#66FF99 RGB102255153

HTML#66FFCC RGB102255204

HTML#66FFFF RGB102255255

HTML#990000 RGB15300

HTML#990033 RGB153051

HTML#990066 RGB1530102

HTML#990099 RGB1530153

HTML#9900CC RGB1530204

HTML#9900FF RGB1530255

HTML#993300 RGB153510

HTML#993333 RGB1535151

HTML#993366 RGB15351102

HTML#993399 RGB15351153

HTML#9933CC RGB15351204

HTML#9933FF RGB15351255

HTML#996600 RGB1531020

HTML#996633 RGB15310251

HTML#996666 RGB153102102

HTML#996699 RGB153102153

HTML#9966CC RGB153102204

HTML#9966FF RGB153102255

HTML#999900 RGB1531530

HTML#999933 RGB15315351

HTML#999966 RGB153153102

HTML#999999 RGB153153153

HTML#9999CC RGB153153204

HTML#9999FF RGB153153255

HTML#99CC00 RGB1532040

HTML#99CC33 RGB15320451

HTML#99CC66 RGB153204102

HTML#99CC99 RGB153204153

HTML#99CCCC RGB153204204

HTML#99CCFF RGB153204255

HTML#99FF00 RGB1532550

HTML#99FF33 RGB15325551

HTML#99FF66 RGB153255102

HTML#99FF99 RGB153255153

HTML#99FFCC RGB153255204

HTML#99FFFF RGB153255255

HTML#CC0000 RGB20400

HTML#CC0033 RGB204051

HTML#CC0066 RGB2040102

HTML#CC0099 RGB2040153

HTML#CC00CC RGB2040204

HTML#CC00FF RGB2040255

HTML#CC3300 RGB204510

HTML#CC3333 RGB2045151

HTML#CC3366 RGB20451102

HTML#CC3399 RGB20451153

HTML#CC33CC RGB20451204

HTML#CC33FF RGB20451255

HTML#CC6600 RGB2041020

HTML#CC6633 RGB20410251

HTML#CC6666 RGB204102102

HTML#CC6699 RGB204102153

HTML#CC66CC RGB204102204

HTML#CC66FF RGB204102255

HTML#CC9900 RGB2041530

HTML#CC9933 RGB20415351

HTML#CC9966 RGB204153102

HTML#CC9999 RGB204153153

HTML#CC99CC RGB204153204

HTML#CC99FF RGB204153255

HTML#CCCC00 RGB2042040

HTML#CCCC33 RGB20420451

HTML#CCCC66 RGB204204102

HTML#CCCC99 RGB204204153

HTML#CCCCCC RGB204204204

HTML#CCCCFF RGB204204255

HTML#CCFF00 RGB2042550

HTML#CCFF33 RGB20425551

HTML#CCFF66 RGB204255102

HTML#CCFF99 RGB204255153

HTML#CCFFCC RGB204255204

HTML#CCFFFF RGB204255255

HTML#FF0000 RGB25500

HTML#FF0033 RGB255051

HTML#FF0066 RGB2550102

HTML#FF0099 RGB2550153

HTML#FF00CC RGB2550204

HTML#FF00FF RGB2550255

HTML#FF3300 RGB255510

HTML#FF3333 RGB2555151

HTML#FF3366 RGB25551102

HTML#FF3399 RGB25551153

HTML#FF33CC RGB25551204

HTML#FF33FF RGB25551255

HTML#FF6600 RGB2551020

HTML#FF6633 RGB25510251

HTML#FF6666 RGB255102102

HTML#FF6699 RGB255102153

HTML#FF66CC RGB255102204

HTML#FF66FF RGB255102255

HTML#FF9900 RGB2551530

HTML#FF9933 RGB25515351

HTML#FF9966 RGB255153102

HTML#FF9999 RGB255153153

HTML#FF99CC RGB255153204

HTML#FF99FF RGB255153255

HTML#FFCC00 RGB2552040

HTML#FFCC33 RGB25520451

HTML#FFCC66 RGB255204102

HTML#FFCC99 RGB255204153

HTML#FFCCCC RGB255204204

HTML#FFCCFF RGB255204255

HTML#FFFF00 RGB2552550

HTML#FFFF33 RGB25525551

HTML#FFFF66 RGB255255102

HTML#FFFF99 RGB255255153

HTML#FFFFCC RGB255255204

HTML#FFFFFF RGB255255255

[edit]

Web-safe colors

In the mid-90s, many displays were only capable of displaying 256 colors.[11] These may be dictated by the hardware or changeable by a "color table". When a color is found (e.g., in an image) that is not one available, a different one had to be used. This can be done by either using the closest color, or by using dithering.

There were various attempts to make a "standard" color palette. A set of colors was needed that could be shown without dithering on 256-color displays; the number 216 was chosen partly because computer operating systems customarily reserved sixteen to twenty colors for their own use; it was also selected because it allows exactly six equally spaced shades of red, green, and blue (6 × 6 × 6 = 216), each from 00 to FF (including both limits).

The list of colors is presented as if it had special properties that render them immune to dithering, but on 256-color displays applications can actually set a palette of any selection of colors that they choose, dithering the rest. These colors were chosen specifically because they matched the palettes selected by various browser applications. There were not very different palettes in use in different browsers.[_citation needed_]

"Web-safe" colors had a flaw in that, on systems such as X11 where the palette is shared between applications, smaller color cubes (5×5×5 or 4×4×4) were allocated by browsers—the "web safe" colors would dither on such systems. Different results were obtained by providing an image with a larger range of colors and allowing the browser to quantize the color space if needed, rather than suffer the quality loss of a double quantization.

As of 2011, personal computers typically[12] have 24-bit (TrueColor) and the use of "web-safe" colors has fallen into practical disuse.

The "web-safe" colors do not all have standard names, but each can be specified by an RGB triplet: each component (red, green, and blue) takes one of the six values from the following table (out of the 256 possible values available for each component in full 24-bit color).

6 shades of each color
KeyHexDecimalFraction
00000
333510.2
6661020.4
9991530.6
C or (12)CC2040.8
F or (15)FF2551

The following table shows all of the "web-safe" colors. One shortcoming of the web-safe palette is its small range of light colors for webpage backgrounds, whereas the intensities at the low end of the range, such as the two darkest, are similar to each other, making them hard to distinguish.