Written by Paul Bourke
May 1995
This table is the "standard" set as used by the SGI X windows server. The values are in the range of 0 to 255 inclusive.
Contribution by Robert Rapplean, C++ program that creates an image that can be folded together to form the RGB colour cube.
A colour space is a means of uniquely specifying a colour. There are a number of colour spaces in common usage depending on the particular industry and/or application involved. For example as humans we normally determine colour by parameters such as brightness, hue, and colourfulness. On computers it is more common to describe colour by three components, normally red, green, and blue. These are related to the excitation of red, green, and blue phosphors on a computer monitor. Another similar system geared more towards the printing industry uses cyan, magenta, and yellow to specify colour, they are related to the reflectance and absorbance of inks on paper.
Some other major colour spaces are:There are generally ways of converting (transforming) between different colour spaces although in most cases the transformation is nonlinear. Some colour spaces for example can represent colours which cannot be represented in others.
The colour space for computer based applications is often visualised by a unit cube. Each colour (red, green, blue) is assigned to one of the three orthogonal coordinate axes in 3D space. An example of such a cube is shown below along with some key colours and their coordinates.
The first set below was originally compiled by Steve Hollasch and is organised as follows: the first column is the descriptive name of the colour; the next three columns are the RGB coordinates in the 0 to 255 range as if the components were being stored in one unsigned byte; the last three columns are the RGB colour coordinates in the range of 0 to 1 inclusive.
Whites antique_white 250 235 215 0.9804 0.9216 0.8431 azure 240 255 255 0.9412 1.0000 1.0000 bisque 255 228 196 1.0000 0.8941 0.7686 blanched_almond 255 235 205 1.0000 0.9216 0.8039 cornsilk 255 248 220 1.0000 0.9725 0.8627 eggshell 252 230 201 0.9900 0.9000 0.7900 floral_white 255 250 240 1.0000 0.9804 0.9412 gainsboro 220 220 220 0.8627 0.8627 0.8627 ghost_white 248 248 255 0.9725 0.9725 1.0000 honeydew 240 255 240 0.9412 1.0000 0.9412 ivory 255 255 240 1.0000 1.0000 0.9412 lavender 230 230 250 0.9020 0.9020 0.9804 lavender_blush 255 240 245 1.0000 0.9412 0.9608 lemon_chiffon 255 250 205 1.0000 0.9804 0.8039 linen 250 240 230 0.9804 0.9412 0.9020 mint_cream 245 255 250 0.9608 1.0000 0.9804 misty_rose 255 228 225 1.0000 0.8941 0.8824 moccasin 255 228 181 1.0000 0.8941 0.7098 navajo_white 255 222 173 1.0000 0.8706 0.6784 old_lace 253 245 230 0.9922 0.9608 0.9020 papaya_whip 255 239 213 1.0000 0.9373 0.8353 peach_puff 255 218 185 1.0000 0.8549 0.7255 seashell 255 245 238 1.0000 0.9608 0.9333 snow 255 250 250 1.0000 0.9804 0.9804 thistle 216 191 216 0.8471 0.7490 0.8471 titanium_white 252 255 240 0.9900 1.0000 0.9400 wheat 245 222 179 0.9608 0.8706 0.7020 white 255 255 255 1.0000 1.0000 1.0000 white_smoke 245 245 245 0.9608 0.9608 0.9608 zinc_white 253 248 255 0.9900 0.9700 1.0000 Greys cold_grey 128 138 135 0.5000 0.5400 0.5300 dim_grey 105 105 105 0.4118 0.4118 0.4118 grey 192 192 192 0.7529 0.7529 0.7529 light_grey 211 211 211 0.8275 0.8275 0.8275 slate_grey 112 128 144 0.4392 0.5020 0.5647 slate_grey_dark 47 79 79 0.1843 0.3098 0.3098 slate_grey_light 119 136 153 0.4667 0.5333 0.6000 warm_grey 128 128 105 0.5000 0.5000 0.4100 Blacks black 0 0 0 0.0000 0.0000 0.0000 ivory_black 41 36 33 0.1600 0.1400 0.1300 lamp_black 46 71 59 0.1800 0.2800 0.2300 Reds alizarin_crimson 227 38 54 0.8900 0.1500 0.2100 brick 156 102 31 0.6100 0.4000 0.1200 cadmium_red_deep 227 23 13 0.8900 0.0900 0.0500 coral 255 127 80 1.0000 0.4980 0.3137 coral_light 240 128 128 0.9412 0.5020 0.5020 deep_pink 255 20 147 1.0000 0.0784 0.5765 english_red 212 61 26 0.8300 0.2400 0.1000 firebrick 178 34 34 0.6980 0.1333 0.1333 geranium_lake 227 18 48 0.8900 0.0700 0.1900 hot_pink 255 105 180 1.0000 0.4118 0.7059 indian_red 176 23 31 0.6900 0.0900 0.1200 light_salmon 255 160 122 1.0000 0.6275 0.4784 madder_lake_deep 227 46 48 0.8900 0.1800 0.1900 maroon 176 48 96 0.6902 0.1882 0.3765 pink 255 192 203 1.0000 0.7529 0.7961 pink_light 255 182 193 1.0000 0.7137 0.7569 raspberry 135 38 87 0.5300 0.1500 0.3400 red 255 0 0 1.0000 0.0000 0.0000 rose_madder 227 54 56 0.8900 0.2100 0.2200 salmon 250 128 114 0.9804 0.5020 0.4471 tomato 255 99 71 1.0000 0.3882 0.2784 venetian_red 212 26 31 0.8300 0.1000 0.1200 Browns beige 163 148 128 0.6400 0.5800 0.5000 brown 128 42 42 0.5000 0.1647 0.1647 brown_madder 219 41 41 0.8600 0.1600 0.1600 brown_ochre 135 66 31 0.5300 0.2600 0.1200 burlywood 222 184 135 0.8706 0.7216 0.5294 burnt_sienna 138 54 15 0.5400 0.2100 0.0600 burnt_umber 138 51 36 0.5400 0.2000 0.1400 chocolate 210 105 30 0.8235 0.4118 0.1176 deep_ochre 115 61 26 0.4500 0.2400 0.1000 flesh 255 125 64 1.0000 0.4900 0.2500 flesh_ochre 255 87 33 1.0000 0.3400 0.1300 gold_ochre 199 120 38 0.7800 0.4700 0.1500 greenish_umber 255 61 13 1.0000 0.2400 0.0500 khaki 240 230 140 0.9412 0.9020 0.5490 khaki_dark 189 183 107 0.7412 0.7176 0.4196 light_beige 245 245 220 0.9608 0.9608 0.8627 peru 205 133 63 0.8039 0.5216 0.2471 rosy_brown 188 143 143 0.7373 0.5608 0.5608 raw_sienna 199 97 20 0.7800 0.3800 0.0800 raw_umber 115 74 18 0.4500 0.2900 0.0700 sepia 94 38 18 0.3700 0.1500 0.0700 sienna 160 82 45 0.6275 0.3216 0.1765 saddle_brown 139 69 19 0.5451 0.2706 0.0745 sandy_brown 244 164 96 0.9569 0.6431 0.3765 tan 210 180 140 0.8235 0.7059 0.5490 van_dyke_brown 94 38 5 0.3700 0.1500 0.0200 Oranges cadmium_orange 255 97 3 1.0000 0.3800 0.0100 cadmium_red_light 255 3 13 1.0000 0.0100 0.0500 carrot 237 145 33 0.9300 0.5700 0.1300 dark_orange 255 140 0 1.0000 0.5490 0.0000 mars_orange 150 69 20 0.5900 0.2700 0.0800 mars_yellow 227 112 26 0.8900 0.4400 0.1000 orange 255 128 0 1.0000 0.5000 0.0000 orange_red 255 69 0 1.0000 0.2706 0.0000 yellow_ochre 227 130 23 0.8900 0.5100 0.0900 Yellows aureoline_yellow 255 168 36 1.0000 0.6600 0.1400 banana 227 207 87 0.8900 0.8100 0.3400 cadmium_lemon 255 227 3 1.0000 0.8900 0.0100 cadmium_yellow 255 153 18 1.0000 0.6000 0.0700 gold 255 215 0 1.0000 0.8431 0.0000 goldenrod 218 165 32 0.8549 0.6471 0.1255 goldenrod_dark 184 134 11 0.7216 0.5255 0.0431 goldenrod_light 250 250 210 0.9804 0.9804 0.8235 goldenrod_pale 238 232 170 0.9333 0.9098 0.6667 light_goldenrod 238 221 130 0.9333 0.8667 0.5098 melon 227 168 105 0.8900 0.6600 0.4100 naplesyellowdeep 255 168 18 1.0000 0.6600 0.0700 yellow 255 255 0 1.0000 1.0000 0.0000 yellow_light 255 255 224 1.0000 1.0000 0.8784 Greens chartreuse 127 255 0 0.4980 1.0000 0.0000 chromeoxidegreen 102 128 20 0.4000 0.5000 0.0800 cinnabar_green 97 179 41 0.3800 0.7000 0.1600 cobalt_green 61 145 64 0.2400 0.5700 0.2500 emerald_green 0 201 87 0.0000 0.7900 0.3400 forest_green 34 139 34 0.1333 0.5451 0.1333 green 0 255 0 0.0000 1.0000 0.0000 green_dark 0 100 0 0.0000 0.3922 0.0000 green_pale 152 251 152 0.5961 0.9843 0.5961 green_yellow 173 255 47 0.6784 1.0000 0.1843 lawn_green 124 252 0 0.4863 0.9882 0.0000 lime_green 50 205 50 0.1961 0.8039 0.1961 mint 189 252 201 0.7400 0.9900 0.7900 olive 59 94 43 0.2300 0.3700 0.1700 olive_drab 107 142 35 0.4196 0.5569 0.1373 olive_green_dark 85 107 47 0.3333 0.4196 0.1843 permanent_green 10 201 43 0.0400 0.7900 0.1700 sap_green 48 128 20 0.1900 0.5000 0.0800 sea_green 46 139 87 0.1804 0.5451 0.3412 sea_green_dark 143 188 143 0.5608 0.7373 0.5608 sea_green_medium 60 179 113 0.2353 0.7020 0.4431 sea_green_light 32 178 170 0.1255 0.6980 0.6667 spring_green 0 255 127 0.0000 1.0000 0.4980 spring_greenmedium 0 250 154 0.0000 0.9804 0.6039 terre_verte 56 94 15 0.2200 0.3700 0.0600 viridian_light 110 255 112 0.4300 1.0000 0.4400 yellow_green 154 205 50 0.6039 0.8039 0.1961 Cyans aquamarine 127 255 212 0.4980 1.0000 0.8314 aquamarinemedium 102 205 170 0.4000 0.8039 0.6667 cyan 0 255 255 0.0000 1.0000 1.0000 cyan_white 224 255 255 0.8784 1.0000 1.0000 turquoise 64 224 208 0.2510 0.8784 0.8157 turquoise_dark 0 206 209 0.0000 0.8078 0.8196 turquoise_medium 72 209 204 0.2824 0.8196 0.8000 turquoise_pale 175 238 238 0.6863 0.9333 0.9333 Blues alice_blue 240 248 255 0.9412 0.9725 1.0000 blue 0 0 255 0.0000 0.0000 1.0000 blue_light 173 216 230 0.6784 0.8471 0.9020 blue_medium 0 0 205 0.0000 0.0000 0.8039 cadet 95 158 160 0.3725 0.6196 0.6275 cobalt 61 89 171 0.2400 0.3500 0.6700 cornflower 100 149 237 0.3922 0.5843 0.9294 cerulean 5 184 204 0.0200 0.7200 0.8000 dodger_blue 30 144 255 0.1176 0.5647 1.0000 indigo 8 46 84 0.0300 0.1800 0.3300 manganese_blue 3 168 158 0.0100 0.6600 0.6200 midnight_blue 25 25 112 0.0980 0.0980 0.4392 navy 0 0 128 0.0000 0.0000 0.5020 peacock 51 161 201 0.2000 0.6300 0.7900 powder_blue 176 224 230 0.6902 0.8784 0.9020 royal_blue 65 105 225 0.2549 0.4118 0.8824 slate_blue 106 90 205 0.4157 0.3529 0.8039 slate_blue_dark 72 61 139 0.2824 0.2392 0.5451 slate_blue_light 132 112 255 0.5176 0.4392 1.0000 slate_blue_medium 123 104 238 0.4824 0.4078 0.9333 sky_blue 135 206 235 0.5294 0.8078 0.9216 sky_blue_deep 0 191 255 0.0000 0.7490 1.0000 sky_blue_light 135 206 250 0.5294 0.8078 0.9804 steel_blue 70 130 180 0.2745 0.5098 0.7059 steel_blue_light 176 196 222 0.6902 0.7686 0.8706 turquoise_blue 0 199 140 0.0000 0.7800 0.5500 ultramarine 18 10 143 0.0700 0.0400 0.5600 Magentas blue_violet 138 43 226 0.5412 0.1686 0.8863 cobalt_violetdeep 145 33 158 0.5700 0.1300 0.6200 magenta 255 0 255 1.0000 0.0000 1.0000 orchid 218 112 214 0.8549 0.4392 0.8392 orchid_dark 153 50 204 0.6000 0.1961 0.8000 orchid_medium 186 85 211 0.7294 0.3333 0.8275 permanent_violet 219 38 69 0.8600 0.1500 0.2700 plum 221 160 221 0.8667 0.6275 0.8667 purple 160 32 240 0.6275 0.1255 0.9412 purple_medium 147 112 219 0.5765 0.4392 0.8588 ultramarine_violet 92 36 110 0.3600 0.1400 0.4300 violet 143 94 153 0.5600 0.3700 0.6000 violet_dark 148 0 211 0.5804 0.0000 0.8275 violet_red 208 32 144 0.8157 0.1255 0.5647 violet_redmedium 199 21 133 0.7804 0.0824 0.5216 violet_red_pale 219 112 147 0.8588 0.4392 0.5765
Calibration of a computer controlled color monitor
Brainard, D.H,
Color Research & Application, 14, 1, pp 23-34 (1989).
Color Monitor Colorimetry
SMPTE Recommended Practice RP 145-1987
Color Temperature for Color Television Studio Monitors
SMPTE Recommended Practice RP 37
Color Science in Television and Display Systems
Sproson, W, N, Adam Hilger Ltd, 1983. ISBN 0-85274-413-7
CIE Colorimetry
Official recommendations of the International
Commission on Illumination, Publication 15.2 1986
CRT Colorimetry:Part 1 Theory and Practice, Part 2 Metrology
Berns, R.S., Motta, R.J. and Gorzynski, M.E., Color Research and
Application, 18, (1993)
Effective Color Displays. Theory and Practice
Travis, D, Academic Press, 1991. ISBN 0-12-697690-2
Color and Its Reproduction
Field, G.G., Graphics Arts Technical, Foundation, 1988, pp. 320-9
Gamma and its disguises: The nonlinear mappings of intensity in perception,
CRT's, Film and Video
C. A. Poynton, SMPTE Journal, December 1993
Measuring Color (second edition),
R. W. G. Hunt, Ellis Horwood 1991, ISBN 0-13-567686-x
On the Gun Independence and Phosphor Consistency of Color Video
Monitors
W.B. Cowan N. Rowell, Color Research and Application, V.11 Supplement 1986
Precision requirements for digital color reproduction
M Stokes MD Fairchild RS Berns, ACM Transactions on graphics, v11 n4 1992
The colorimetry of self luminous displays - a bibliography
CIE Publication n.87, Central Bureau of the CIE, Vienna 1990
The Reproduction of Color in PhotoGraphy, Printing and Television
R. W. G. Hunt, Fountain Press, Tolworth, England, 1987
Fully Utilizing Photo CD Images, Article No. 4, PhotoYCC Color Encoding and
Compression Schemes
Eastman Kodak Company, Rochester NY (USA) (1993).
Digital halftoning
Robert Ulichney, MIT Press, 1987, ISBN 0-262-21009-6
Achieving consistent colour representation within WWW documents between browsers (NetScape, MSIE) and hardware platforms (Macintosh, Windows, UNIX) requires some knowledge of how browsers allocate colours when running in 8 bit mode (256 colours). If 16, 24 or higher colour modes are being used then exact colour representation is achieved without dithering and the following doesn't apply.
Colour in HTML is represented by 3 hexadecimal (hex) pairs, representing the red, green, blue components of the final colour. Each RGB component is stored as 1 byte (unsigned) ranging numerically from 0 to 255, in hex this is "00" to "ff". The colour model is the familiar colour cube used in computer graphics.
Any colour can be requested by a WWW page but the browser will not necessarily use that colour precisely due to hardware limitations. Even if the hardware is capable of 24 bit colour, the actual RGB components are often rounded to multiples of 4, fortunately this is not discernable by humans even if it could be resolved by the monitor. In index colour system such as the most common 256 colour system, the actual colours that can be displayed are quantised into much coarser steps. The operating system generally needs some colours for its own use such as drawing window boundaries, menus, etc. Browsers on Macintosh and MSWindows systems use 216 of the available 256 colours, the remaining 40 are left available for the operating system to allocate as necessary. If colours are used that are not in the palette of 256 colours the browser will either convert the colour to one that is closest in the palette or it will give the bext representation of the requested colour by dithering a number of the available colours. If these colours are being used for backgrounds and/or text it can often mean the difference between a readable and unreadable page.
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Consider the rectangle on the right. It is created using a colour that is in the standard 216 palette used by browsers (NetScape and MSIE). |
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The rectangle on the right however uses a colour not in the standard palette. It will either look like a solid colour if you have a 16 or 24 bit colour system or dithered if you have a 256 indexed colour system. |
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The set of colours which, if used, will look the same on all 256 palette systems is simply a 6x6x6 (216) partitioning of the colour cube. The discrete steps in each RGB component are
| 000 | 051 | 102 | 153 | 204 | 255 |
or in hex
| 00 | 33 | 66 | 99 | cc | ff |
or as percentages
| 000% | 020% | 040% | 060% | 080% | 100% |
This doesn't include any grey scale levels (where r = g = b) but fortunately the 40 system wide colours usually include a good range of grey values.
| 00 00 00 | 00 00 33 | 00 00 66 | 00 00 99 | 00 00 CC | 00 00 FF |
| 00 33 00 | 00 33 33 | 00 33 66 | 00 33 99 | 00 33 CC | 00 33 FF |
| 00 66 00 | 00 66 33 | 00 66 66 | 00 66 99 | 00 66 CC | 00 66 FF |
| 00 99 00 | 00 99 33 | 00 99 66 | 00 99 99 | 00 99 CC | 00 99 FF |
| 00 CC 00 | 00 CC 33 | 00 CC 66 | 00 CC 99 | 00 CC CC | 00 CC FF |
| 00 FF 00 | 00 FF 33 | 00 FF 66 | 00 FF 99 | 00 FF CC | 00 FF FF |
| 33 00 00 | 33 00 33 | 33 00 66 | 33 00 99 | 33 00 CC | 33 00 FF |
| 33 33 00 | 33 33 33 | 33 33 66 | 33 33 99 | 33 33 CC | 33 33 FF |
| 33 66 00 | 33 66 33 | 33 66 66 | 33 66 99 | 33 66 CC | 33 66 FF |
| 33 99 00 | 33 99 33 | 33 99 66 | 33 99 99 | 33 99 CC | 33 99 FF |
| 33 CC 00 | 33 CC 33 | 33 CC 66 | 33 CC 99 | 33 CC CC | 33 CC FF |
| 33 FF 00 | 33 FF 33 | 33 FF 66 | 33 FF 99 | 33 FF CC | 33 FF FF |
| 66 00 00 | 66 00 33 | 66 00 66 | 66 00 99 | 66 00 CC | 66 00 FF |
| 66 33 00 | 66 33 33 | 66 33 66 | 66 33 99 | 66 33 CC | 66 33 FF |
| 66 66 00 | 66 66 33 | 66 66 66 | 66 66 99 | 66 66 CC | 66 66 FF |
| 66 99 00 | 66 99 33 | 66 99 66 | 66 99 99 | 66 99 CC | 66 99 FF |
| 66 CC 00 | 66 CC 33 | 66 CC 66 | 66 CC 99 | 66 CC CC | 66 CC FF |
| 66 FF 00 | 66 FF 33 | 66 FF 66 | 66 FF 99 | 66 FF CC | 66 FF FF |
| 99 00 00 | 99 00 33 | 99 00 66 | 99 00 99 | 99 00 CC | 99 00 FF |
| 99 33 00 | 99 33 33 | 99 33 66 | 99 33 99 | 99 33 CC | 99 33 FF |
| 99 66 00 | 99 66 33 | 99 66 66 | 99 66 99 | 99 66 CC | 99 66 FF |
| 99 99 00 | 99 99 33 | 99 99 66 | 99 99 99 | 99 99 CC | 99 99 FF |
| 99 CC 00 | 99 CC 33 | 99 CC 66 | 99 CC 99 | 99 CC CC | 99 CC FF |
| 99 FF 00 | 99 FF 33 | 99 FF 66 | 99 FF 99 | 99 FF CC | 99 FF FF |
| CC 00 00 | CC 00 33 | CC 00 66 | CC 00 99 | CC 00 CC | CC 00 FF |
| CC 33 00 | CC 33 33 | CC 33 66 | CC 33 99 | CC 33 CC | CC 33 FF |
| CC 66 00 | CC 66 33 | CC 66 66 | CC 66 99 | CC 66 CC | CC 66 FF |
| CC 99 00 | CC 99 33 | CC 99 66 | CC 99 99 | CC 99 CC | CC 99 FF |
| CC CC 00 | CC CC 33 | CC CC 66 | CC CC 99 | CC CC CC | CC CC FF |
| CC FF 00 | CC FF 33 | CC FF 66 | CC FF 99 | CC FF CC | CC FF FF |
| FF 00 00 | FF 00 33 | FF 00 66 | FF 00 99 | FF 00 CC | FF 00 FF |
| FF 33 00 | FF 33 33 | FF 33 66 | FF 33 99 | FF 33 CC | FF 33 FF |
| FF 66 00 | FF 66 33 | FF 66 66 | FF 66 99 | FF 66 CC | FF 66 FF |
| FF 99 00 | FF 99 33 | FF 99 66 | FF 99 99 | FF 99 CC | FF 99 FF |
| FF CC 00 | FF CC 33 | FF CC 66 | FF CC 99 | FF CC CC | FF CC FF |
| FF FF 00 | FF FF 33 | FF FF 66 | FF FF 99 | FF FF CC | FF FF FF |
The above table was generated by slicing along the red axis of the colour cube, that is, each table above is a sampled plane parallel to the green-blue plane. Slices could be generated along the other two axes as well.
Laid out as a PhotoShop table, the 256 colour palette for the Macintosh is shown on the left and the 216 palette for MS based machines is shown on the right.
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All three slices can be viewed below
Note: The above refers to what colours should be used when creating simple colour diagrams, for example, backgrounds, logos, etc. For photographic or other images with more than 256 colours it is better to use an adaptive colour table when creating the gif rather than dithering to the browser palette.
C code to create colour table.