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test_blackbody.py
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'''
test_blackbody.py - Test cases for blackbody.py
License:
Copyright (C) 2008 Mark Kness
Author - Mark Kness - [email protected]
This file is part of ColorPy.
ColorPy is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation, either version 3 of
the License, or (at your option) any later version.
ColorPy is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with ColorPy. If not, see <http://www.gnu.org/licenses/>.
'''
import math, random, numpy
import colormodels
import blackbody
STEFAN_BOLTZMAN = 5.670e-8 # W/(m^2 K^4)
def blackbody_total_intensity (T_K, start_wl_nm, end_wl_nm):
'''Get the sum of the specific intensity, at 1 nm increments, from start_wl_nm to end_wl_nm.'''
total = 0.0
for wl_nm in xrange (start_wl_nm, end_wl_nm+1):
specific = blackbody.blackbody_specific_intensity (wl_nm, T_K)
total += specific
return total
def blackbody_total_intensity_stefan_boltzman (T_K):
'''Get the sum of the intensities over all wavelengths, assuming the Stefan-Boltzman law.'''
total = STEFAN_BOLTZMAN * math.pow (T_K, 4)
# TODO - What (if any) scaling is required of this result to correspond to blackbody_specific_intensity()?
# I am not sure, and there is a mismatch.
# not entirely sure about the following scaling... See Shu.
scaling = blackbody.SPEED_OF_LIGHT # almost
total *= scaling
return total
# Tests
def test_Wyszecki_p29 ():
'''Calculations re Wyszecki p29 table.'''
T = 1336.0 # 'Gold' point
xyz = blackbody.blackbody_color (T)
print 'blackbody color at gold point', str (xyz)
# this source is supposed to be 0.11 cd/cm^2 = 1100 cd/m^2
# whereas monitors are c. 80 cd/m^2 to 300 cd/m^2
def test_stefan_boltzman (verbose=1):
'''Test that the total intensity over many wavelengths matches the Stefan-Boltman formula.
NOTE - This currently does not match. I am not sure what the situation is.'''
T = 100.0
sb_test0 = blackbody_total_intensity_stefan_boltzman (T)
print 'sb_test0', sb_test0
sb_test1 = blackbody_total_intensity (T, 0, 1000)
print 'sb_test1', sb_test1
sb_test2 = blackbody_total_intensity (T, 0, 10000)
print 'sb_test2', sb_test2
sb_test3 = blackbody_total_intensity (T, 0, 100000)
print 'sb_test3', sb_test3
# following start to get slow...
#sb_test4 = blackbody_total_intensity (T, 0, 1000000)
#print 'sb_test4', sb_test4
#sb_test5 = blackbody_total_intensity (T, 0, 10000000)
#print 'sb_test5', sb_test5
# compare the computed result with the stefan-boltzman formula
# TODO - these do not match, although the T^4 behavior is observed...
T_list = [100.0, 1000.0, 4000.0, 6500.0, 10000.0, 15000.0]
for T in T_list:
total_sb = blackbody_total_intensity_stefan_boltzman (T)
# larger wavelength intervals capture more of the total power
total1 = blackbody_total_intensity (T, 360, 830)
total2 = blackbody_total_intensity (T, 1, 1000)
total3 = blackbody_total_intensity (T, 1, 10000)
total4 = blackbody_total_intensity (T, 1, 100000)
ratio = total4 / total_sb
#if verbose >= 1:
if True:
print 'T', T
print 'total_sb', total_sb
print 'total1', total1
print 'total2', total2
print 'total3', total3
print 'total4', total4
print 'ratio', ratio
def test_blackbody (verbose=0):
'''Test the blackbody functions.'''
num_passed = 0
num_failed = 0
# a few calls with specific arguments
test_zero1 = blackbody_total_intensity (100.0, 0, 100)
test_zero2 = blackbody_total_intensity (0.0, 0, 100)
test_zero3 = blackbody_total_intensity (100000.0, 0, 100)
test_zero4 = blackbody_total_intensity (0.0, 0, 100000)
test_zero5 = blackbody_total_intensity (100000.0, 0, 100000)
num_passed += 5
# determine the color for several temperatures - 10000.0 is a particularly good range
temp_ranges = [100.0, 1000.0, 10000.0, 100000.0, 1000000.0 ]
for T0 in temp_ranges:
for i in xrange (0, 20):
T_K = T0 * random.random()
xyz = blackbody.blackbody_color (T_K)
if verbose >= 1:
print 'T = %g K, xyz = %s' % (T_K, str (xyz))
num_passed += 1 # didn't exception
msg = 'test_blackbody() : %d tests passed, %d tests failed' % (
num_passed, num_failed)
print msg
# Table of xy chromaticities for blackbodies
# From (I think): Judd and Wyszecki, Color in Business, Science and Industry, 1975, p. 164
book_chrom_table = numpy.array ([
[ 1000.0, 0.6528, 0.3444],
[ 1400.0, 0.5985, 0.3858],
[ 1600.0, 0.5732, 0.3993],
[ 1800.0, 0.5493, 0.4082],
[ 2000.0, 0.5267, 0.4133],
[ 2200.0, 0.5056, 0.4152],
[ 2400.0, 0.4862, 0.4147],
[ 2600.0, 0.4682, 0.4123],
[ 2800.0, 0.4519, 0.4086],
[ 3000.0, 0.4369, 0.4041],
[ 3200.0, 0.4234, 0.3990],
[ 3400.0, 0.4110, 0.3935],
[ 3600.0, 0.3999, 0.3879],
[ 3800.0, 0.3897, 0.3823],
[ 4200.0, 0.3720, 0.3714],
[ 4500.0, 0.3608, 0.3636],
[ 4800.0, 0.3510, 0.3562],
[ 5200.0, 0.3397, 0.3472],
[ 5800.0, 0.3260, 0.3354],
[ 6500.0, 0.3135, 0.3237],
[ 7500.0, 0.3004, 0.3103],
[ 8500.0, 0.2908, 0.3000],
[10000.0, 0.2807, 0.2884],
[30000.0, 0.2501, 0.2489]])
def test_book (verbose=1):
'''Test that the computed chromaticities match an existing table, from Judd and Wyszecki.'''
num_passed = 0
num_failed = 0
(num_rows, num_cols) = book_chrom_table.shape
for i in xrange (0, num_rows):
T = book_chrom_table [i][0]
book_x = book_chrom_table [i][1]
book_y = book_chrom_table [i][2]
# calculate color for T
xyz = blackbody.blackbody_color (T)
colormodels.xyz_normalize (xyz)
dx = xyz [0] - book_x
dy = xyz [1] - book_y
# did we match the tablulated result?
tolerance = 2.0e-4
passed = (math.fabs (dx) <= tolerance) and (math.fabs (dy) <= tolerance)
if passed:
status = 'pass'
else:
status = 'FAILED'
msg = 'test_book() : T = %g : calculated x,y = %g,%g : book values x,y = %g,%g : errors = %g,%g' % (
T, xyz [0], xyz [1], book_x, book_y, dx, dy)
if verbose >= 1:
print msg
if not passed:
pass
raise ValueError, msg
if passed:
num_passed += 1
else:
num_failed += 1
msg = 'test_book() : %d tests passed, %d tests failed' % (
num_passed, num_failed)
print msg
# Tests
def test (verbose=0):
'''Test the blackbody module.'''
test_blackbody (verbose=verbose)
test_book (verbose=verbose)
#test_stefan_boltzman (verbose=verbose)