2 # -*- coding: utf-8 -*-
7 import aces_ocio.generateLUT as genlut
8 from aces_ocio.util import ColorSpace, mat44FromMat33
15 def createLogC(gamut, transferFunction, exposureIndex, name, lutDir, lutResolution1d):
16 name = "%s (EI%s) - %s" % (transferFunction, exposureIndex, gamut)
17 if transferFunction == "":
18 name = "Linear - %s" % gamut
20 name = "%s (EI%s)" % (transferFunction, exposureIndex)
29 IDT_maker_version = "0.08"
32 blackSignal = 0.003907
34 encodingGain = 0.256598
35 encodingOffset = 0.391007
38 return (math.log(EI/nominalEI)/math.log(2) * (0.89 - 1) / 3 + 1) * encodingGain
40 def LogCInverseParametersForEI(EI) :
42 slope = 1.0 / (cut * math.log(10))
43 offset = math.log10(cut) - slope * cut
45 gray = midGraySignal / gain
46 # The higher the EI, the lower the gamma
47 encGain = gainForEI(EI)
48 encOffset = encodingOffset
50 nz = ((95.0 / 1023.0 - encOffset) / encGain - offset) / slope
51 encOffset = encodingOffset - math.log10(1 + nz) * encGain
52 # Calculate some intermediate values
54 b = nz - blackSignal / gray
55 e = slope * a * encGain
56 f = encGain * (slope * b + offset) + encOffset
57 # Manipulations so we can return relative exposure
66 'cut' : (cut - b) / a,
72 def logCtoLinear(codeValue, exposureIndex):
73 p = LogCInverseParametersForEI(exposureIndex)
74 breakpoint = p['e'] * p['cut'] + p['f']
75 if (codeValue > breakpoint):
76 linear = (pow(10,(codeValue/1023.0 - p['d']) / p['c']) - p['b']) / p['a']
78 linear = (codeValue/1023.0 - p['f']) / p['e']
80 #print( codeValue, linear )
84 cs.toReferenceTransforms = []
86 if transferFunction == "V3 LogC":
87 data = array.array('f', "\0" * lutResolution1d * 4)
88 for c in range(lutResolution1d):
89 data[c] = logCtoLinear(1023.0*c/(lutResolution1d-1), int(exposureIndex))
91 lut = "%s_to_linear.spi1d" % ("%s_%s" % (transferFunction, exposureIndex))
93 # Remove spaces and parentheses
94 lut = lut.replace(' ', '_').replace(')', '_').replace('(', '_')
96 genlut.writeSPI1D(lutDir + "/" + lut, 0.0, 1.0, data, lutResolution1d, 1)
98 #print( "Writing %s" % lut)
99 cs.toReferenceTransforms.append( {
102 'interpolation':'linear',
103 'direction':'forward'
106 if gamut == 'Wide Gamut':
107 cs.toReferenceTransforms.append( {
109 'matrix':mat44FromMat33([0.680206, 0.236137, 0.083658,
110 0.085415, 1.017471, -0.102886,
111 0.002057, -0.062563, 1.060506]),
112 'direction':'forward'
115 cs.fromReferenceTransforms = []
118 def createColorSpaces(lutDir, lutResolution1d):
121 transferFunction = "V3 LogC"
123 #EIs = [160.0, 200.0, 250.0, 320.0, 400.0, 500.0, 640.0, 800.0, 1000.0, 1280.0, 1600.0, 2000.0, 2560.0, 3200.0]
124 EIs = [160, 200, 250, 320, 400, 500, 640, 800, 1000, 1280, 1600, 2000, 2560, 3200]
129 LogCEIfull = createLogC(gamut, transferFunction, EI, "LogC", lutDir, lutResolution1d)
130 colorspaces.append(LogCEIfull)
134 LogCEIlinearization = createLogC("", transferFunction, EI, "LogC", lutDir, lutResolution1d)
135 colorspaces.append(LogCEIlinearization)
138 LogCEIprimaries = createLogC(gamut, "", defaultEI, "LogC", lutDir, lutResolution1d)
139 colorspaces.append(LogCEIprimaries)