4 import aces_ocio.generateLUT as genlut
5 from aces_ocio.util import ColorSpace, mat44FromMat33
12 def createLogC(gamut, transferFunction, exposureIndex, name, lutDir, lutResolution1d):
13 name = "%s (EI%s) - %s" % (transferFunction, exposureIndex, gamut)
14 if transferFunction == "":
15 name = "Linear - %s" % gamut
17 name = "%s (EI%s)" % (transferFunction, exposureIndex)
26 IDT_maker_version = "0.08"
29 blackSignal = 0.003907
31 encodingGain = 0.256598
32 encodingOffset = 0.391007
35 return (math.log(EI/nominalEI)/math.log(2) * (0.89 - 1) / 3 + 1) * encodingGain
37 def LogCInverseParametersForEI(EI) :
39 slope = 1.0 / (cut * math.log(10))
40 offset = math.log10(cut) - slope * cut
42 gray = midGraySignal / gain
43 # The higher the EI, the lower the gamma
44 encGain = gainForEI(EI)
45 encOffset = encodingOffset
47 nz = ((95.0 / 1023.0 - encOffset) / encGain - offset) / slope
48 encOffset = encodingOffset - math.log10(1 + nz) * encGain
49 # Calculate some intermediate values
51 b = nz - blackSignal / gray
52 e = slope * a * encGain
53 f = encGain * (slope * b + offset) + encOffset
54 # Manipulations so we can return relative exposure
63 'cut' : (cut - b) / a,
69 def logCtoLinear(codeValue, exposureIndex):
70 p = LogCInverseParametersForEI(exposureIndex)
71 breakpoint = p['e'] * p['cut'] + p['f']
72 if (codeValue > breakpoint):
73 linear = (pow(10,(codeValue/1023.0 - p['d']) / p['c']) - p['b']) / p['a']
75 linear = (codeValue/1023.0 - p['f']) / p['e']
77 #print( codeValue, linear )
81 cs.toReferenceTransforms = []
83 if transferFunction == "V3 LogC":
84 data = array.array('f', "\0" * lutResolution1d * 4)
85 for c in range(lutResolution1d):
86 data[c] = logCtoLinear(1023.0*c/(lutResolution1d-1), int(exposureIndex))
88 lut = "%s_to_linear.spi1d" % ("%s_%s" % (transferFunction, exposureIndex))
90 # Remove spaces and parentheses
91 lut = lut.replace(' ', '_').replace(')', '_').replace('(', '_')
93 genlut.writeSPI1D(lutDir + "/" + lut, 0.0, 1.0, data, lutResolution1d, 1)
95 #print( "Writing %s" % lut)
96 cs.toReferenceTransforms.append( {
99 'interpolation':'linear',
100 'direction':'forward'
103 if gamut == 'Wide Gamut':
104 cs.toReferenceTransforms.append( {
106 'matrix':mat44FromMat33([0.680206, 0.236137, 0.083658,
107 0.085415, 1.017471, -0.102886,
108 0.002057, -0.062563, 1.060506]),
109 'direction':'forward'
112 cs.fromReferenceTransforms = []
115 def createColorSpaces(lutDir, lutResolution1d):
118 transferFunction = "V3 LogC"
120 #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]
121 EIs = [160, 200, 250, 320, 400, 500, 640, 800, 1000, 1280, 1600, 2000, 2560, 3200]
126 LogCEIfull = createLogC(gamut, transferFunction, EI, "LogC", lutDir, lutResolution1d)
127 colorspaces.append(LogCEIfull)
131 LogCEIlinearization = createLogC("", transferFunction, EI, "LogC", lutDir, lutResolution1d)
132 colorspaces.append(LogCEIlinearization)
135 LogCEIprimaries = createLogC(gamut, "", defaultEI, "LogC", lutDir, lutResolution1d)
136 colorspaces.append(LogCEIprimaries)