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April 17, 2019 20:36
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JavaScript nm to RGB color function
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| nmToRGB: function(wavelength){ | |
| var Gamma = 0.80, | |
| IntensityMax = 255, | |
| factor, red, green, blue; | |
| if((wavelength >= 380) && (wavelength<440)){ | |
| red = -(wavelength - 440) / (440 - 380); | |
| green = 0.0; | |
| blue = 1.0; | |
| }else if((wavelength >= 440) && (wavelength<490)){ | |
| red = 0.0; | |
| green = (wavelength - 440) / (490 - 440); | |
| blue = 1.0; | |
| }else if((wavelength >= 490) && (wavelength<510)){ | |
| red = 0.0; | |
| green = 1.0; | |
| blue = -(wavelength - 510) / (510 - 490); | |
| }else if((wavelength >= 510) && (wavelength<580)){ | |
| red = (wavelength - 510) / (580 - 510); | |
| green = 1.0; | |
| blue = 0.0; | |
| }else if((wavelength >= 580) && (wavelength<645)){ | |
| red = 1.0; | |
| green = -(wavelength - 645) / (645 - 580); | |
| blue = 0.0; | |
| }else if((wavelength >= 645) && (wavelength<781)){ | |
| red = 1.0; | |
| green = 0.0; | |
| blue = 0.0; | |
| }else{ | |
| red = 0.0; | |
| green = 0.0; | |
| blue = 0.0; | |
| }; | |
| // Let the intensity fall off near the vision limits | |
| if((wavelength >= 380) && (wavelength<420)){ | |
| factor = 0.3 + 0.7*(wavelength - 380) / (420 - 380); | |
| }else if((wavelength >= 420) && (wavelength<701)){ | |
| factor = 1.0; | |
| }else if((wavelength >= 701) && (wavelength<781)){ | |
| factor = 0.3 + 0.7*(780 - wavelength) / (780 - 700); | |
| }else{ | |
| factor = 0.0; | |
| }; | |
| if (red !== 0){ | |
| red = Math.round(IntensityMax * Math.pow(red * factor, Gamma)); | |
| } | |
| if (green !== 0){ | |
| green = Math.round(IntensityMax * Math.pow(green * factor, Gamma)); | |
| } | |
| if (blue !== 0){ | |
| blue = Math.round(IntensityMax * Math.pow(blue * factor, Gamma)); | |
| } | |
| return [red,green,blue]; | |
| } |
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From this page: https://academo.org/demos/wavelength-to-colour-relationship/