def blackbody_spectrum(T_K):
'''Get the spectrum of a blackbody, as a numpy array.'''
spectrum = ciexyz.empty_spectrum()
num_wl = spectrum.shape[0]
for i in range(0, num_wl):
# Intensity per unit wavelength.
specific_intensity = blackbody_specific_intensity(spectrum[i][0], T_K)
# Scale by size of wavelength interval.
spectrum[i][1] = specific_intensity * ciexyz.delta_wl_nm * 1.0e-9
return spectrum
def get_constant_illuminant():
'''Get an illuminant, with spectrum constant over wavelength, normalized to Y = 1.0.'''
illuminant = ciexyz.empty_spectrum()
(num_wl, num_cols) = illuminant.shape
for i in range(0, num_wl):
illuminant[i][1] = 1.0
xyz = ciexyz.xyz_from_spectrum(illuminant)
if xyz[1] != 0.0:
scaling = 1.0 / xyz[1]
illuminant[:, 1] *= scaling
return illuminant
def cie_matching_functions_plot ():
'''Plot the CIE XYZ matching functions, as three spectral subplots.'''
# get 'spectra' for x,y,z matching functions
spectrum_x = ciexyz.empty_spectrum()
spectrum_y = ciexyz.empty_spectrum()
spectrum_z = ciexyz.empty_spectrum()
(num_wl, num_cols) = spectrum_x.shape
for i in range (0, num_wl):
wl_nm = spectrum_x [i][0]
xyz = ciexyz.xyz_from_wavelength (wl_nm)
spectrum_x [i][1] = xyz [0]
spectrum_y [i][1] = xyz [1]
spectrum_z [i][1] = xyz [2]
# Plot three separate subplots, with CIE X in the first, CIE Y in the second, and CIE Z in the third.
# Label appropriately for the whole plot.
pylab.clf ()
# X
pylab.subplot (3,1,1)
pylab.title ('1931 CIE XYZ Matching Functions')
pylab.ylabel ('CIE $X$')
spectrum_subplot (spectrum_x)
tighten_x_axis (spectrum_x [:,0])
# Y
pylab.subplot (3,1,2)
pylab.ylabel ('CIE $Y$')
spectrum_subplot (spectrum_y)
tighten_x_axis (spectrum_x [:,0])
# Z
pylab.subplot (3,1,3)
pylab.xlabel ('Wavelength (nm)')
pylab.ylabel ('CIE $Z$')
spectrum_subplot (spectrum_z)
tighten_x_axis (spectrum_x [:,0])
# done
filename = 'CIEXYZ_Matching'
print ('Saving plot %s' % str (filename))
pylab.savefig (filename)
def init():
'''Initialize CIE Illuminant D65. This runs on module startup.'''
first_wl = _Illuminant_D65_table[0][0]
# for now, only consider the part in the normal visible range (360-830 nm)
first_index = ciexyz.start_wl_nm - first_wl
table_first = _Illuminant_D65_table[first_index][0]
assert (table_first == 360), 'Mismatch finding 360 nm entry in D65 table'
global _Illuminant_D65
_Illuminant_D65 = ciexyz.empty_spectrum()
(num_wl, num_cols) = _Illuminant_D65.shape
for i in range(0, num_wl):
_Illuminant_D65[i][1] = _Illuminant_D65_table[first_index + i][1]
# normalization - illuminant is scaled so that Y = 1.0
xyz = ciexyz.xyz_from_spectrum(_Illuminant_D65)
scaling = 1.0 / xyz[1]
_Illuminant_D65[:, 1] *= scaling
def scattered_visual_brightness ():
'''Plot the perceptual brightness of Rayleigh scattered light.'''
# get 'spectra' for y matching functions and multiply by 1/wl^4
spectrum_y = ciexyz.empty_spectrum()
(num_wl, num_cols) = spectrum_y.shape
for i in range (0, num_wl):
wl_nm = spectrum_y [i][0]
rayleigh = math.pow (550.0 / wl_nm, 4)
xyz = ciexyz.xyz_from_wavelength (wl_nm)
spectrum_y [i][1] = xyz [1] * rayleigh
pylab.clf ()
pylab.title ('Perceptual Brightness of Rayleigh Scattered Light')
pylab.xlabel ('Wavelength (nm)')
pylab.ylabel ('CIE $Y$ / $\lambda^4$')
spectrum_subplot (spectrum_y)
tighten_x_axis (spectrum_y [:,0])
# done
filename = 'Visual_scattering'
print ('Saving plot %s' % str (filename))
pylab.savefig (filename)
def visible_spectrum_plot ():
'''Plot the visible spectrum, as a plot vs wavelength.'''
spectrum = ciexyz.empty_spectrum()
(num_wl, num_cols) = spectrum.shape
# get rgb colors for each wavelength
rgb_colors = numpy.empty ((num_wl, 3))
for i in range (0, num_wl):
xyz = ciexyz.xyz_from_wavelength (spectrum [i][0])
rgb = colormodels.rgb_from_xyz (xyz)
rgb_colors [i] = rgb
# scale to make brightest rgb value = 1.0
rgb_max = numpy.max (rgb_colors)
scaling = 1.0 / rgb_max
rgb_colors *= scaling
# plot colors and rgb values vs wavelength
color_vs_param_plot (
spectrum [:,0],
rgb_colors,
'The Visible Spectrum',
'VisibleSpectrum',
tight = True,
xlabel = r'Wavelength (nm)',
ylabel = r'RGB Color')
def visible_spectrum_table (filename='visible_spectrum.html'):
'''Write an HTML table with the visible spectrum colors.'''
spectrum = ciexyz.empty_spectrum()
(num_wl, num_cols) = spectrum.shape
# get rgb colors for each wavelength
rgb_colors_1 = numpy.empty ((num_wl, 3))
rgb_colors_2 = numpy.empty ((num_wl, 3))
for i in range (0, num_wl):
xyz = ciexyz.xyz_from_wavelength (spectrum [i][0])
rgb_1 = colormodels.rgb_from_xyz (xyz)
rgb_2 = colormodels.brightest_rgb_from_xyz (xyz)
rgb_colors_1 [i] = rgb_1
rgb_colors_2 [i] = rgb_2
# scale 1 to make brightest rgb value = 1.0
rgb_max = numpy.max (rgb_colors_1)
scaling = 1.0 / rgb_max
rgb_colors_1 *= scaling
# write HTML file
def write_link (f, url, text):
'''Write an html link.'''
link = '<a href="%s">%s</a><br/>\n' % (url, text)
f.write (link)
f = open (filename, 'w')
# html headers
f.write ('<html>\n')
f.write ('<head>\n')
f.write ('<title>Colors of Pure Spectral Lines</title>\n')
f.write ('</head>\n')
f.write ('<body>\n')
f.write ('<p><h1>Colors of Pure Spectral Lines</h1></p>\n')
f.write ('<p>%s</p>\n' % 'White added to undisplayable pure colors to fit into rgb space.')
f.write ('<hr/>\n')
# table header
f.write ('<table border cellpadding="5">\n')
f.write ('<tr>\n')
f.write ('<th>Wavelength</th>\n')
f.write ('<th>R</th>\n')
f.write ('<th>G</th>\n')
f.write ('<th>B</th>\n')
f.write ('<th>Hex Code</th>\n')
f.write ('<th width=200>Full Brightness</th>\n')
f.write ('<th width=200>Perceptual Brightness</th>\n')
f.write ('</tr>\n')
# each row
for i in range (0, num_wl):
irgb_1 = colormodels.irgb_from_rgb (rgb_colors_1 [i])
irgb_2 = colormodels.irgb_from_rgb (rgb_colors_2 [i])
red = irgb_2 [0]
green = irgb_2 [1]
blue = irgb_2 [2]
hexstr_1 = colormodels.irgb_string_from_irgb (irgb_1)
hexstr_2 = colormodels.irgb_string_from_irgb (irgb_2)
iwl = spectrum [i][0]
code = '%.1f nm' % iwl
f.write ('<tr>\n')
f.write ('<td>%s</td>\n' % (code))
f.write ('<td>%d</td>\n' % (red))
f.write ('<td>%d</td>\n' % (green))
f.write ('<td>%d</td>\n' % (blue))
f.write ('<td>%s</td>\n' % (hexstr_2))
swatch = " "
f.write ('<td bgcolor="%s">%s</td>\n' % (hexstr_2, swatch))
f.write ('<td bgcolor="%s">%s</td>\n' % (hexstr_1, swatch))
f.write ('</tr>\n')
f.write ('</table>\n')
# references
f.write ('<hr/>\n')
f.write ('<p>References</p>\n')
# one source for data
write_link (f, 'http://goffgrafix.com/pantone-rgb-100.php', 'Goffgrafix.com')
# another source with basically the same data
write_link (f, 'http://www.sandaleo.com/pantone.asp', 'Sandaleo.com')
# one with more colors including metallic (also some errors), not quite consistent with the first two
write_link (f, 'http://www.loral.org/Z/Colors/100.html',
'Loral.org - Conversions based on CorelDRAW v12 Pantone Solid Coated or Pastel Coated tables and sRGB color space.')
# some colors for various sports teams
write_link (f, 'http://www.pennjersey.info/forums/questions-answers/7895-pantone-colors-colleges-university-mlb-nfl-teams.html',
'Pantone colors for some sports teams.')
# some colors for various national flags
write_link (f, 'http://desktoppub.about.com/od/colorpalettes/l/aa_flagcolors.htm', 'What color is your flag? Pantone colors for some flags.')
write_link (f, 'http://desktoppub.about.com/library/weekly/blcpflagsrwb.htm', 'Red, White, & Blue - Pantone colors for some flags.')
write_link (f, 'http://desktoppub.about.com/library/weekly/blcpflagsyellow.htm', 'Yellow or Gold - Pantone colors for some flags.')
write_link (f, 'http://desktoppub.about.com/library/weekly/blcpflagsgreen.htm', 'Green - Pantone colors for some flags.')
write_link (f, 'http://desktoppub.about.com/library/weekly/blcpatrioticswatches.htm', 'Color swatches - Pantone colors for some flags.')
# official Pantone webpages
write_link (f, 'http://pantone.com/pages/pantone/Pantone.aspx?pg=19970&ca=25', 'An official PANTONE page')
write_link (f, 'http://pantone.com/pages/products/product.aspx?ca=1&pid=293&', 'Another official PANTONE page')
# html ending
f.write ('</body>\n')
f.write ('</html>\n')
f.close()