/
study_apple_log.py
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/
study_apple_log.py
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# -*- coding: utf-8 -*-
"""
"""
# import standard libraries
import os
# import third-party libraries
import numpy as np
from colour import LUT3D, write_LUT
from colour.io import write_image, read_image
from colour.utilities import tstack
from colour.models import eotf_sRGB, log_encoding_ARRILogC4, \
log_encoding_SLog3, oetf_ARIBSTDB67, eotf_inverse_ST2084, \
oetf_inverse_ARIBSTDB67
# import my libraries
import test_pattern_generator2 as tpg
import plot_utility as pu
# information
__author__ = 'Toru Yoshihara'
__copyright__ = 'Copyright (C) 2023 - Toru Yoshihara'
__license__ = 'New BSD License - https://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Toru Yoshihara'
__email__ = 'toru.ver.11 at-sign gmail.com'
__all__ = []
EXP_RANGE = 12
EXP_REF_VAL = 0.18
def log_encoding_apple_log(x):
"""
Scence linear to Apple Log.
Parameters
----------
x : ndarray
A scene linear light (1.0 is SDR diffuse white)
Examples
--------
>>> log_encoding_apple_log(0.18)
0.488271418052
Note
----
Valid range of `x` is from 2^-12 to 2^12
"""
lut_1d = np.load("./secret/apple_log_encode_lut.npy")
y = np.interp(x, xp=lut_1d[..., 0], fp=lut_1d[..., 1])
return y
def log_decoding_apple_log(x):
"""
Scence Apple Log to linear.
Parameters
----------
x : ndarray
Apple Log value
Examples
--------
>>> log_decoding_apple_log(0.488271418052)
0.179995837368
"""
lut_1d = np.load("./secret/apple_log_decode_lut.npy")
y = np.interp(x, xp=lut_1d[..., 0], fp=lut_1d[..., 1])
return y
def create_test_pattern_for_verify_on_Resolve():
width = 1920
height = 1080
ref_val = 0.18
exp_range = 6
# apply oetf
x_scene = np.linspace(
ref_val*(2**(-exp_range)), ref_val*(2**(exp_range)), width)
apple_log = log_encoding_apple_log(x_scene)
apple_log_img = tpg.h_mono_line_to_img(apple_log, height)
fname = f"./img/verify_apple_log_src-{exp_range}_to_{exp_range}_stops.png"
print(fname)
tpg.img_wirte_float_as_16bit_int(fname, apple_log_img)
# apply eotf
x_apple_log = np.linspace(0, 1, width)
scene_linear = log_decoding_apple_log(x_apple_log)
apple_linear_img = tpg.h_mono_line_to_img(scene_linear, height)
fname = "./img/verify_scene_linear_src-0_to_1023_apple_log.exr"
print(fname)
write_image(apple_linear_img, fname)
def create_test_pattern_for_apple_log_encoding_analysis():
width = 1920
height = 1080
ref_val = EXP_REF_VAL
exp_range = EXP_RANGE
x = tpg.get_log2_x_scale(
sample_num=width, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
img = tpg.h_mono_line_to_img(x, height)
fname = f"./img/src_log2_-{exp_range}_to_{exp_range}_stops.exr"
print(fname)
write_image(img, fname)
def create_test_pattern_for_apple_log_decoding_analysis():
width = 1920
height = 1080
x = np.linspace(0, 1, width)
img = tpg.h_mono_line_to_img(x, height)
fname = "./img/src_0_to_1.png"
print(fname)
tpg.img_wirte_float_as_16bit_int(fname, img)
def debug_plot_apple_log_encoding():
fname = "./secret/apple_log_encode_out.exr"
img = read_image(fname)
width = img.shape[1]
ref_val = EXP_REF_VAL
exp_range = EXP_RANGE
x_resolve = tpg.get_log2_x_scale(
sample_num=width, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
y_resolve = img[0, ..., 1]
x_lut = tpg.get_log2_x_scale(
sample_num=36, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
y_lut = log_encoding_apple_log(x_lut)
fig, ax1 = pu.plot_1_graph(
fontsize=20,
figsize=(12, 8),
bg_color=(0.96, 0.96, 0.96),
graph_title="Apple Log Encoding Characteristics",
xlabel=r"Stops from 18% gray",
ylabel="Code Value",
axis_label_size=None,
ylim=[-0.05, 1.65],
ytick=[x * 0.2 for x in range(9)],
legend_size=17,
linewidth=3)
ax1.set_xscale('log', base=2)
ax1.set_xticks([2**i for i in range(-exp_range, exp_range+1, 2)])
ax1.set_xticklabels([str(i) for i in range(-exp_range, exp_range+1, 2)])
ax1.plot(
x_resolve/ref_val, y_resolve, color=pu.RED, label="Apple_Log_EXR_Out")
ax1.plot(
x_lut/ref_val, y_lut, '--o', color=pu.GREEN, lw=1,
label="Apple_Log_1DLUT")
pu.show_and_save(
fig=fig, legend_loc='upper left', show=True,
save_fname="./img/apple_log_encoding_characteristics.png")
def debug_plot_apple_log_decoding():
fname = "./secret/apple_log_decode_out.exr"
img = read_image(fname)
width = img.shape[1]
x_resolve = np.linspace(0, 1, width)
y_resolve = img[0, ..., 1]
x_lut = np.linspace(0, 1, 256)
y_lut = log_decoding_apple_log(x_lut)
fig, ax1 = pu.plot_1_graph(
fontsize=20,
figsize=(12, 8),
bg_color=(0.96, 0.96, 0.96),
graph_title="Apple Log Encoding Characteristics",
xlabel="Code Value (10-bit)",
ylabel="Scene Linear Value",
axis_label_size=None,
legend_size=17,
linewidth=3)
ax1.set_yscale('log', base=2)
ax1.plot(
x_resolve, y_resolve, color=pu.RED, label="Apple_Log_EXR_Out")
ax1.plot(
x_lut, y_lut, '--', color=pu.GREEN, lw=1,
label="Apple_Log_1DLUT")
pu.show_and_save(
fig=fig, legend_loc='upper left', show=True,
save_fname="./img/apple_log_decoding_characteristics.png")
def save_apple_log_as_1dlut():
# encoding function
fname = "./secret/apple_log_encode_out.exr"
img = read_image(fname)
width = img.shape[1]
ref_val = EXP_REF_VAL
exp_range = EXP_RANGE
x = tpg.get_log2_x_scale(
sample_num=width, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
y = img[0, ..., 1]
lut = tstack([x, y])
np.save("./secret/apple_log_encode_lut.npy", lut)
# deconding function
fname = "./secret/apple_log_decode_out.exr"
img = read_image(fname)
width = img.shape[1]
x = np.linspace(0, 1, width)
y = img[0, ..., 1]
lut = tstack([x, y])
np.save("./secret/apple_log_decode_lut.npy", lut)
def create_el_zone_3dlut(
decode_func=log_decoding_apple_log, fname_prefix="Apple_Log"):
"""
A test implementation of EL Zone System.
https://www.elzonesystem.com/
Please note that this is not an official implementation.
It's an unofficial version based on my own interpretation.
"""
def rgb_to_y_bt2020(rgb):
y = rgb[..., 0] * 0.2627 + rgb[..., 1] * 0.6780 + rgb[..., 2] * 0.0593
return y
gray18 = 0.18
lut3d_num_of_grid = 65
exp_range = 7
stops_list = [
-7, -6, -5, -4, -3, -2, -1, -0.5, 0, 0.5, 1, 2, 3, 4, 5, 6, 7]
color_list_8bit = [
[3, 3, 3], [98, 71, 155], [158, 126, 184], [24, 116, 167],
[39, 174, 228], [27, 168, 75], [93, 187, 71], [148, 200, 64],
[144, 140, 135], [251, 232, 0], [255, 248, 166], [244, 112, 42],
[247, 170, 71], [239, 28, 38], [229, 126, 140], [243, 190, 192],
[255, 255, 255]
]
color_list_linear = eotf_sRGB(np.array(color_list_8bit) / 255)
color_list_log = color_list_linear ** (1/2.4)
log_value = LUT3D.linear_table(lut3d_num_of_grid)
out_lut = np.zeros_like(log_value)
linear = decode_func(log_value)
linear_y = rgb_to_y_bt2020(linear)
for idx, stops in enumerate(stops_list):
if stops == -exp_range:
upper_diff = stops_list[idx + 1] - stops_list[idx]
high_stops = stops + upper_diff / 2
low_stops = -20
elif stops == exp_range:
lower_diff = stops_list[idx] - stops_list[idx - 1]
high_stops = 20
low_stops = stops - lower_diff / 2
else:
upper_diff = stops_list[idx + 1] - stops_list[idx]
lower_diff = stops_list[idx] - stops_list[idx - 1]
high_stops = stops + upper_diff / 2
low_stops = stops - lower_diff / 2
low_value = gray18 * (2 ** low_stops)
high_value = gray18 * (2 ** high_stops)
# print(f"{stops}, {low_stops}, {high_stops}, {low_value}, {high_value}")
t_idx = ((low_value <= linear_y) & (linear_y < high_value))
out_lut[t_idx] = color_list_log[idx]
info_txt = f"EL Zone System for {fname_prefix}"
lut_fname = f"./lut/EL_Zone_System_for_{fname_prefix}_"
lut_fname += f"{lut3d_num_of_grid}-grid_BT1886.cube"
lut3d = LUT3D(table=out_lut, name=info_txt)
write_LUT(lut3d, lut_fname)
def plot_apple_log_encodings():
num_of_sample = 43
ref_val = 0.18
exp_range = 8
x = tpg.get_log2_x_scale(
sample_num=num_of_sample, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
y = log_encoding_apple_log(x)
y_10bit = y * 1023
fig, ax1 = pu.plot_1_graph(
fontsize=20,
figsize=(12, 8),
bg_color=(0.96, 0.96, 0.96),
graph_title="Apple Log Encoding Characteristics",
graph_title_size=None,
xlabel=r"Stops from 18% gray",
ylabel="Code Value (10-bit)",
axis_label_size=None,
legend_size=17,
xlim=None,
ylim=[-30, 1053],
xtick=None,
ytick=[x * 64 for x in range(16)] + [1023],
xtick_size=None, ytick_size=None,
linewidth=3,
minor_xtick_num=None,
minor_ytick_num=None)
ax1.set_xscale('log', base=2)
ax1.set_xticks([2**i for i in range(-exp_range, exp_range+1)])
ax1.set_xticklabels([str(i) for i in range(-exp_range, exp_range+1)])
# ax1.set_xticks([-8 + x for x in range(exp_range * 2 + 1)])
ax1.plot(x/ref_val, y_10bit, '-o', color=pu.RED, label="Apple Log")
pu.show_and_save(
fig=fig, legend_loc='upper left', show=True,
save_fname="./img/Apple_Log_Encode.png")
def plot_log_encodings():
def to_10bit(x, clip=False):
if clip:
return np.round(np.clip(x, 0.0, 1.0) * 1023).astype(np.uint16)
else:
return np.round(x * 1023).astype(np.uint16)
num_of_sample = 43
ref_val = 0.18
exp_range = 12
x = tpg.get_log2_x_scale(
sample_num=num_of_sample, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
apple_log = log_encoding_apple_log(x)
apple_log_10bit = to_10bit(apple_log)
logc4 = log_encoding_ARRILogC4(x)
logc4_10bit = to_10bit(logc4)
slog3 = log_encoding_SLog3(x)
slog3_10_bit = to_10bit(slog3)
hlg = oetf_ARIBSTDB67(x)
hlg_10bit = np.round((hlg * 219 + 16) * 4).astype(np.uint16)
st2084 = eotf_inverse_ST2084(x*100)
st2084_10bit = to_10bit(st2084)
fig, ax1 = pu.plot_1_graph(
fontsize=20,
figsize=(12, 8),
bg_color=(0.96, 0.96, 0.96),
graph_title="Log Encoding Characteristics",
graph_title_size=None,
xlabel=r"Stops from 18% gray",
ylabel="Code Value (10-bit)",
axis_label_size=None,
legend_size=17,
xlim=None,
ylim=[-30, 1053],
xtick=None,
ytick=[x * 64 for x in range(16)] + [1023],
xtick_size=None, ytick_size=None,
linewidth=2,
minor_xtick_num=None,
minor_ytick_num=None)
ax1.set_xscale('log', base=2)
ax1.set_xticks([2**i for i in range(-exp_range, exp_range+1, 2)])
ax1.set_xticklabels([str(i) for i in range(-exp_range, exp_range+1, 2)])
ax1.plot(
x/ref_val, st2084_10bit, '-o', color=pu.ORANGE,
label="ST 2084 (Inverse EOTF)")
ax1.plot(
x/ref_val, slog3_10_bit, '-o', color=pu.BLUE, label="S-Log3")
ax1.plot(
x/ref_val, logc4_10bit, '-o', color=pu.GREEN,
label="LogC4 (Full Range)")
ax1.plot(
x/ref_val, hlg_10bit, '-o', color=pu.BROWN, label="HLG (ARIB STD-B67)")
ax1.plot(
x/ref_val, apple_log_10bit, '-o', color=pu.RED, label="Apple Log")
pu.show_and_save(
fig=fig, legend_loc='upper left', show=True,
save_fname="./img/Log_Encodes.png")
def create_tp_for_verify_el_zone_system_lut_apple_log():
width = 1920
height = 1080
num_of_sample = width
ref_val = 0.18
exp_range = 8
x = tpg.get_log2_x_scale(
sample_num=num_of_sample, ref_val=ref_val,
min_exposure=-exp_range, max_exposure=exp_range)
y = log_encoding_apple_log(x)
img = tpg.h_mono_line_to_img(y, height)
fname = "./img/src_apple_log_log2_"
fname += f"-{exp_range}_to_{exp_range}_stops.exr"
print(fname)
write_image(img, fname)
if __name__ == '__main__':
os.chdir(os.path.dirname(os.path.abspath(__file__)))
# create_test_pattern_for_apple_log_encoding_analysis()
# create_test_pattern_for_apple_log_decoding_analysis()
# create_test_pattern_for_verify_on_Resolve()
# save_apple_log_as_1dlut()
# debug_plot_apple_log_encoding()
# debug_plot_apple_log_decoding()
# plot_apple_log_encodings()
# plot_log_encodings()
# create_el_zone_3dlut(
# decode_func=oetf_inverse_ARIBSTDB67, fname_prefix="HLG")
# create_el_zone_3dlut(
# decode_func=log_decoding_apple_log, fname_prefix="Apple_Log")
# create_tp_for_verify_el_zone_system_lut_apple_log()