move calculation of correlated colour temperature to the new module blackbody

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 201 insertions, 0 deletions

diff --git a/src/blackbody.py b/src/blackbody.py
new file mode 100644
index 0000000..42fc6ff
--- /dev/null
+++ b/src/blackbody.py
@@ -0,0 +1,201 @@
+#!/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]
+