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authorMattias Andrée <maandree@operamail.com>2014-03-16 21:51:07 +0100
committerMattias Andrée <maandree@operamail.com>2014-03-16 21:51:13 +0100
commit2f469a3dcb8d08421b3d369fa47e68b19c1106ed (patch)
tree671f6e6a053f45d010dff00054883d7bcf0b2486 /src/blackbody.py
parentm doc (diff)
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move calculation of correlated colour temperature to the new module blackbody
Signed-off-by: Mattias Andrée <maandree@operamail.com>
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+#!/usr/bin/env python3
+
+# Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import math
+
+from colour import *
+
+
+
+# /usr/share/blueshift
+DATADIR = 'res'
+
+
+
+def series_d(temperature):
+ '''
+ Calculate the colour for a blackbody temperature
+
+ Using `lambda t : divide_by_maximum(series_d(t))` as the algorithm is better than just `series_d`
+
+ @param temperature:float The blackbody temperature in kelvins, must be inside [4000, 7000]
+ @return :(float, float, float) The red, green and blue components of the white point
+ '''
+ x = 0
+ ks = ((0.244063, 0), (0.09911, 1), (2.9678, 2), (-4.6070, 3))
+ if temperature > 7000:
+ ks = ((0.237040, 0), (0.24748, 1), (1.9018, 2), (-2.0064, 3))
+ for (k, d) in ks:
+ x += k * 10 ** (d * 3) / temperature ** d
+ y = 2.870 * x - 3.000 * x ** 2 - 0.275
+ return ciexyy_to_srgb(x, y, 1.0)
+
+
+def simple_whitepoint(temperature):
+ '''
+ Calculate the colour for a blackbody temperature using a simple algorithm
+
+ @param temperature:float The blackbody temperature in kelvins, not guaranteed for values outside [1000, 40000]
+ @return :(float, float, float) The red, green and blue components of the white point
+ '''
+ r, g, b = 1, 1, 1
+ temp = temperature / 100
+ if temp > 66:
+ temp -= 60
+ r = 1.292936186 * temp ** 0.1332047592
+ g = 1.129890861 * temp ** -0.0755148492
+ else:
+ g = 0.390081579 * math.log(temp) - 0.631841444
+ if temp <= 19:
+ b = 0
+ elif temp < 66:
+ b = 0.543206789 * math.log(temp - 10) - 1.196254089
+ return (r, g, b)
+
+
+cmf_2deg_cache = None
+def cmf_2deg(temperature):
+ '''
+ Calculate the colour for a blackbody temperature using raw CIE 1931 2 degree CMF data with interpolation
+
+ Using `lambda t : divide_by_maximum(cmf_2deg(t))` as the algorithm is better than just `cmf_2deg`
+
+ @param temperature:float The blackbody temperature in kelvins, clipped to [1000, 40000]
+ @return :(float, float, float) The red, green and blue components of the white point
+ '''
+ global cmf_2deg_cache
+ if cmf_2deg_cache is None:
+ with open(DATADIR + '/2deg', 'rb') as file:
+ cmf_2deg_cache = file.read()
+ cmf_2deg_cache = cmf_2deg_cache.decode('utf-8', 'error').split('\n')
+ cmf_2deg_cache = filter(lambda x : not x == '', cmf_2deg_cache)
+ cmf_2deg_cache = [[float(x) for x in x_y.split(' ')] for x_y in cmf_2deg_cache]
+ temp = min(max(1000, temperature), 40000)
+ x, y = 0, 0
+ if (temp % 100) == 0:
+ (x, y) = cmf_2deg_cache[int((temp - 1000) // 100)]
+ else:
+ temp -= 1000
+ (x1, y1) = cmf_2deg_cache[int(temp // 100)]
+ (x2, y2) = cmf_2deg_cache[int(temp // 100 + 1)]
+ temp = (temp % 100) / 100
+ x = x1 * temp + x2 * (1 - temp)
+ y = y1 * temp + y2 * (1 - temp)
+ return ciexyy_to_srgb(x, y, 1.0)
+
+
+cmf_10deg_cache = None
+def cmf_10deg(temperature):
+ '''
+ Calculate the colour for a blackbody temperature using raw CIE 1964 10 degree CMF data with interpolation
+
+ Using `lambda t : divide_by_maximum(cmf_10deg(t))` as the algorithm is better than just `cmf_10deg`
+
+ @param temperature:float The blackbody temperature in kelvins, clipped to [1000, 40000]
+ @return :(float, float, float) The red, green and blue components of the white point
+ '''
+ global cmf_10deg_cache
+ if cmf_10deg_cache is None:
+ with open(DATADIR + '/10deg', 'rb') as file:
+ cmf_10deg_cache = file.read()
+ cmf_10deg_cache = cmf_10deg_cache.decode('utf-8', 'error').split('\n')
+ cmf_10deg_cache = filter(lambda x : not x == '', cmf_10deg_cache)
+ cmf_10deg_cache = [[float(x) for x in x_y.split(' ')] for x_y in cmf_10deg_cache]
+ temp = min(max(1000, temperature), 40000)
+ x, y = 0, 0
+ if (temp % 100) == 0:
+ (x, y) = cmf_10deg_cache[int((temp - 1000) // 100)]
+ else:
+ temp -= 1000
+ (x1, y1) = cmf_10deg_cache[int(temp // 100)]
+ (x2, y2) = cmf_10deg_cache[int(temp // 100 + 1)]
+ temp = (temp % 100) / 100
+ x = x1 * temp + x2 * (1 - temp)
+ y = y1 * temp + y2 * (1 - temp)
+ return ciexyy_to_srgb(x, y, 1)
+
+
+redshift_cache, redshift_old_cache = None, None
+def redshift(temperature, old_version = False, linear_interpolation = False):
+ '''
+ Calculate the colour for a blackbody temperature using same data as in the program redshift
+
+ @param temperature:float The blackbody temperature in kelvins, clipped to [1000, 25100] (100 more kelvins than in redshift)
+ @param old_version:bool Whether to the method used in redshift<=1.8, in which case
+ `temperature` is clipped to [1000, 10000] (1 more kelvin than in redshift)
+ @param linear_interpolation:bool Whether to interpolate one linear RGB instead of sRGB
+ @return :(float, float, float) The red, green and blue components of the white point
+ '''
+ global redshift_cache, redshift_old_cache
+ cache = None
+ if not old_version:
+ if redshift_cache is None:
+ with open(DATADIR + '/redshift', 'rb') as file:
+ redshift_cache = file.read()
+ redshift_cache = redshift_cache.decode('utf-8', 'error').split('\n')
+ redshift_cache = filter(lambda x : not x == '', redshift_cache)
+ redshift_cache = [[float(x) for x in r_g_b.split(' ')] for r_g_b in redshift_cache]
+ cache = redshift_cache
+ else:
+ if redshift_old_cache is None:
+ with open(DATADIR + '/redshift_old', 'rb') as file:
+ redshift_old_cache = file.read()
+ redshift_old_cache = redshift_old_cache.decode('utf-8', 'error').split('\n')
+ redshift_old_cache = filter(lambda x : not x == '', redshift_old_cache)
+ redshift_old_cache = [[float(x) for x in r_g_b.split(' ')] for r_g_b in redshift_old_cache]
+ cache = redshift_old_cache
+ temp = min(max(1000, temperature), 10000 if old_version else 25100)
+ r, g, b = 1, 1, 1
+ if (temp % 100) == 0:
+ (r, g, b) = cache[int((temp - 1000) // 100)]
+ else:
+ temp -= 1000
+ (r1, g1, b1) = cache[int(temp // 100)]
+ (r2, g2, b2) = cache[int(temp // 100 + 1)]
+ temp = (temp % 100) / 100
+ if linear_interpolation:
+ (r, g, b) = standard_to_linear(r, g, b)
+ r = r1 * temp + r2 * (1 - temp)
+ g = g1 * temp + g2 * (1 - temp)
+ b = b1 * temp + b2 * (1 - temp)
+ if linear_interpolation:
+ (r, g, b) = linear_to_standard(r, g, b)
+ return (r, g, b)
+
+
+
+def divide_by_maximum(rgb):
+ '''
+ Divide all colour components by the value of the most prominent colour component
+
+ @param rgb:[float, float, float] The three colour components
+ @return :[float, float, float] The three colour components divided by the maximum
+ '''
+ m = max([abs(x) for x in rgb])
+ if m != 0:
+ return [x / m for x in rgb]
+ return rgb
+
+
+def clip_whitepoint(rgb):
+ '''
+ Clip all colour components to fit inside [0, 1]
+
+ @param rgb:[float, float, float] The three colour components
+ @return :[float, float, float] The three colour components clipped
+ '''
+ return [min(max(0, x), 1) for x in rgb]
+