init

wavelength2rgb.py

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+#!/usr/bin/env python
+from __future__ import division
+
+def wavelength_to_rgb(wavelength, gamma=0.8):
+
+    '''
+    noah.org
+    http://www.noah.org/wiki/Wavelength_to_RGB_in_Python
+
+    This converts a given wavelength into an approximate RGB value.
+    The given wavelength is in nanometers.
+    The range of wavelength is 380 nm through 750 nm.
+
+    Based on code by Dan Bruton
+    http://www.physics.sfasu.edu/astro/color/spectra.html
+    '''
+
+    wavelength = float(wavelength)
+    if 440. >= wavelength >= 380.:
+        attenuation = 0.3 + 0.7 * (wavelength - 380) / (440 - 380)
+        R = ((-(wavelength - 440) / (440 - 380)) * attenuation) ** gamma
+        G = 0.
+        B = (1. * attenuation) ** gamma
+    elif wavelength >= 440 and wavelength <= 490:
+        R = 0.0
+        G = ((wavelength - 440) / (490 - 440)) ** gamma
+        B = 1.
+    elif wavelength >= 490 and wavelength <= 510:
+        R = 0.
+        G = 1.
+        B = (-(wavelength - 510) / (510 - 490)) ** gamma
+    elif wavelength >= 510 and wavelength <= 580:
+        R = ((wavelength - 510) / (580 - 510)) ** gamma
+        G = 1.
+        B = 0.
+    elif wavelength >= 580 and wavelength <= 645:
+        R = 1.0
+        G = (-(wavelength - 645) / (645 - 580)) ** gamma
+        B = 0.
+    elif wavelength >= 645 and wavelength <= 750:
+        attenuation = 0.3 + 0.7 * (750 - wavelength) / (750 - 645)
+        R = (1.0 * attenuation) ** gamma
+        G = 0.
+        B = 0.
+    else:
+        R = 0.
+        G = 0.
+        B = 0.
+
+    R = int(R*255)
+    G = int(G*255)
+    B = int(B*255)
+
+    assert 255>=R>=0 and 255>=G>=0 and 255>=B>=0
+
+    return R,G,B
+
+if __name__ == '__main__':
+    from argparse import ArgumentParser
+    p = ArgumentParser()
+    p.add_argument('wavelength_nm',help='wavelength in nm',type=float)
+    p.add_argument('--gamma',type=float,default=0.8)
+    p = p.parse_args()
+
+    R,G,B = wavelength_to_rgb(p.wavelength_nm,p.gamma)
+
+    print(R)
+    print(G)
+    print(B)