X-Git-Url: http://users.mur.at/ms/git/gitweb/?p=OpenColorIO-Configs.git;a=blobdiff_plain;f=aces%2Fluts%2Fslog2.py;fp=aces%2Fluts%2Fslog2.py;h=656827df049b357033b550b4129ab2ee96fbbb2c;hp=0000000000000000000000000000000000000000;hb=ea0a4385de103d2f811936e5f9e29a97ff4be8aa;hpb=4c13f6d0e40c33c922ef20bec91fe59194fcad14

diff --git a/aces/luts/slog2.py b/aces/luts/slog2.py
new file mode 100755
index 0000000..656827d
--- /dev/null
+++ b/aces/luts/slog2.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+
+import math
+
+# IT's annoying that the 1023,4 and 4095,16 almost, but dont exactly, cancel. UGH
+# The intent is clearly to have the same mapping, but it's not done very well.
+# Sony engineers and/or the Academy should pick one of these mappings for both.
+
+def SLog_to_lin(x):
+    return (math.pow(10.0,(((((x*1023.0)/4.0-16.0)/219.0)-0.616596-0.03)/0.432699))-0.037584)*0.9
+
+def SLog2_to_lin(x):
+    if x < 0.030001222851889303:
+        return (x-0.030001222851889303 ) * 0.28258064516129
+    return (219.0*(math.pow(10.0, ((x-0.616596-0.03)/0.432699)) - 0.037584) /155.0)
+
+steps = 21
+for i in xrange(steps):
+    x = i/(steps-1.0)
+    print x, SLog_to_lin(x), SLog2_to_lin(x)
+
+def WriteSPI1D(filename, fromMin, fromMax, data):
+    f = file(filename,'w')
+    f.write("Version 1\n")
+    f.write("From %s %s\n" % (fromMin, fromMax))
+    f.write("Length %d\n" % len(data))
+    f.write("Components 1\n")
+    f.write("{\n")
+    for value in data:
+        f.write("        %s\n" % value)
+    f.write("}\n")
+    f.close()
+
+def Fit(value, fromMin, fromMax, toMin, toMax):
+    if fromMin == fromMax:
+        raise ValueError("fromMin == fromMax")
+    return (value - fromMin) / (fromMax - fromMin) * (toMax - toMin) + toMin
+
+"""
+5500K:
+
+ACESR = 0.8764457030 * Rraw +  0.0145411681 * Graw +  0.1090131290 * Braw;
+ACESG = 0.0774075345 * Rraw +  0.9529571767 * Graw + -0.0303647111 * Braw;
+ACESB = 0.0573564351 * Rraw + -0.1151066335 * Graw +  1.0577501984 * Braw;
+
+3200K:
+
+ACESR = 1.0110238740 * Rraw +  -0.1362526051 * Graw +  0.1252287310 * Braw;
+ACESG = 0.1011994504 * Rraw +   0.9562196265 * Graw + -0.0574190769 * Braw;
+ACESB = 0.0600766530 * Rraw +  -0.1010185315 * Graw +  1.0409418785 * Braw;
+"""
+
+"""
+NUM_SAMPLES = 2**11
+RANGE = (-0.125, 1.125)
+data = []
+for i in xrange(NUM_SAMPLES):
+    x = i/(NUM_SAMPLES-1.0)
+    x = Fit(x, 0.0, 1.0, RANGE[0], RANGE[1])
+    data.append(SLog10_to_lin(x))
+WriteSPI1D('slog2.spi1d', RANGE[0], RANGE[1], data)
+"""