--- /dev/null
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Implements support for *ARRI* colorspaces conversions and transfer functions.
+"""
+
+from __future__ import division
+
+import array
+import math
+import os
+
+import PyOpenColorIO as ocio
+
+import aces_ocio.generate_lut as genlut
+from aces_ocio.utilities import ColorSpace, mat44_from_mat33, sanitize
+
+__author__ = 'ACES Developers'
+__copyright__ = 'Copyright (C) 2014 - 2015 - ACES Developers'
+__license__ = ''
+__maintainer__ = 'ACES Developers'
+__email__ = 'aces@oscars.org'
+__status__ = 'Production'
+
+__all__ = ['create_log_c',
+ 'create_colorspaces']
+
+
+def create_log_c(gamut,
+ transfer_function,
+ exposure_index,
+ lut_directory,
+ lut_resolution_1d,
+ aliases):
+ """
+ Creates colorspace covering the conversion from LogC to ACES, with various transfer
+ functions and encoding gamuts covered
+
+ Parameters
+ ----------
+ gamut : str
+ The name of the encoding gamut to use.
+ transfer_function : str
+ The name of the transfer function to use
+ exposure_index : str
+ The exposure index to use
+ lut_directory : str or unicode
+ The directory to use when generating LUTs
+ lut_resolution_1d : int
+ The resolution of generated 1D LUTs
+ aliases : list of str
+ Aliases for this colorspace
+
+ Returns
+ -------
+ ColorSpace
+ A ColorSpace container class referencing the LUTs, matrices and identifying
+ information for the requested colorspace.
+ """
+
+ name = '%s (EI%s) - %s' % (transfer_function, exposure_index, gamut)
+ if transfer_function == '':
+ name = 'Linear - ARRI %s' % gamut
+ if gamut == '':
+ name = 'Curve - %s (EI%s)' % (transfer_function, exposure_index)
+
+ cs = ColorSpace(name)
+ cs.description = name
+ cs.aliases = aliases
+ cs.equality_group = ''
+ cs.family = 'Input/ARRI'
+ cs.is_data = False
+
+ if gamut and transfer_function:
+ cs.aces_transform_id = (
+ 'IDT.ARRI.Alexa-v3-logC-EI%s.a1.v1' % exposure_index)
+
+ # A linear space needs allocation variables.
+ if transfer_function == '':
+ cs.allocation_type = ocio.Constants.ALLOCATION_LG2
+ cs.allocation_vars = [-8, 5, 0.00390625]
+
+ IDT_maker_version = '0.08'
+
+ nominal_EI = 400
+ black_signal = 0.003907
+ mid_gray_signal = 0.01
+ encoding_gain = 0.256598
+ encoding_offset = 0.391007
+
+ def gain_for_EI(EI):
+ return (math.log(EI / nominal_EI) / math.log(2) * (
+ 0.89 - 1) / 3 + 1) * encoding_gain
+
+ def log_c_inverse_parameters_for_EI(EI):
+ cut = 1 / 9
+ slope = 1 / (cut * math.log(10))
+ offset = math.log10(cut) - slope * cut
+ gain = EI / nominal_EI
+ gray = mid_gray_signal / gain
+ # The higher the EI, the lower the gamma.
+ enc_gain = gain_for_EI(EI)
+ enc_offset = encoding_offset
+ for i in range(0, 3):
+ nz = ((95 / 1023 - enc_offset) / enc_gain - offset) / slope
+ enc_offset = encoding_offset - math.log10(1 + nz) * enc_gain
+
+ a = 1 / gray
+ b = nz - black_signal / gray
+ e = slope * a * enc_gain
+ f = enc_gain * (slope * b + offset) + enc_offset
+
+ # Ensuring we can return relative exposure.
+ s = 4 / (0.18 * EI)
+ t = black_signal
+ b += a * t
+ a *= s
+ f += e * t
+ e *= s
+
+ return {'a': a,
+ 'b': b,
+ 'cut': (cut - b) / a,
+ 'c': enc_gain,
+ 'd': enc_offset,
+ 'e': e,
+ 'f': f}
+
+ def normalized_log_c_to_linear(code_value, exposure_index):
+ p = log_c_inverse_parameters_for_EI(exposure_index)
+ breakpoint = p['e'] * p['cut'] + p['f']
+ if code_value > breakpoint:
+ linear = ((pow(10, (code_value - p['d']) / p['c']) -
+ p['b']) / p['a'])
+ else:
+ linear = (code_value - p['f']) / p['e']
+ return linear
+
+ cs.to_reference_transforms = []
+
+ if transfer_function == 'V3 LogC':
+ data = array.array('f', '\0' * lut_resolution_1d * 4)
+ for c in range(lut_resolution_1d):
+ data[c] = normalized_log_c_to_linear(c / (lut_resolution_1d - 1),
+ int(exposure_index))
+
+ lut = '%s_to_linear.spi1d' % (
+ '%s_%s' % (transfer_function, exposure_index))
+
+ lut = sanitize(lut)
+
+ genlut.write_SPI_1d(
+ os.path.join(lut_directory, lut),
+ 0,
+ 1,
+ data,
+ lut_resolution_1d,
+ 1)
+
+ cs.to_reference_transforms.append({
+ 'type': 'lutFile',
+ 'path': lut,
+ 'interpolation': 'linear',
+ 'direction': 'forward'})
+
+ if gamut == 'Wide Gamut':
+ cs.to_reference_transforms.append({
+ 'type': 'matrix',
+ 'matrix': mat44_from_mat33([0.680206, 0.236137, 0.083658,
+ 0.085415, 1.017471, -0.102886,
+ 0.002057, -0.062563, 1.060506]),
+ 'direction': 'forward'})
+
+ cs.from_reference_transforms = []
+ return cs
+
+
+def create_colorspaces(lut_directory, lut_resolution_1d):
+ """
+ Generates the colorspace conversions.
+
+ Parameters
+ ----------
+ lut_directory : str or unicode
+ The directory to use when generating LUTs
+ lut_resolution_1d : int
+ The resolution of generated 1D LUTs
+
+ Returns
+ -------
+ list
+ A list of colorspaces for ARRI cameras and encodings
+ """
+
+ colorspaces = []
+
+ transfer_function = 'V3 LogC'
+ gamut = 'Wide Gamut'
+
+ # EIs = [160, 200, 250, 320, 400, 500, 640, 800,
+ # 1000, 1280, 1600, 2000, 2560, 3200]
+ EIs = [160, 200, 250, 320, 400, 500, 640, 800,
+ 1000, 1280, 1600, 2000, 2560, 3200]
+ default_EI = 800
+
+ # Full Conversion
+ for EI in EIs:
+ log_c_EI_full = create_log_c(
+ gamut,
+ transfer_function,
+ EI,
+ lut_directory,
+ lut_resolution_1d,
+ ['%sei%s_%s' % ('logc3', str(EI), 'arriwide')])
+ colorspaces.append(log_c_EI_full)
+
+ # Linearization Only
+ for EI in [800]:
+ log_c_EI_linearization = create_log_c(
+ '',
+ transfer_function,
+ EI,
+ lut_directory,
+ lut_resolution_1d,
+ ['crv_%sei%s' % ('logc3', str(EI))])
+ colorspaces.append(log_c_EI_linearization)
+
+ # Primaries Only
+ log_c_EI_primaries = create_log_c(
+ gamut,
+ '',
+ default_EI,
+ lut_directory,
+ lut_resolution_1d,
+ ['%s_%s' % ('lin', 'arriwide')])
+ colorspaces.append(log_c_EI_primaries)
+
+ return colorspaces
projects / OpenColorIO-Configs.git / blobdiff