path: root/src/curve.py

#!/usr/bin/env python3

# Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
# 
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
import math

from colour import *



# /usr/share/blueshift
DATADIR = '.'

# Mapping input and output maximum values + 1
i_size = 2 ** 8
o_size = 2 ** 16

# Red, green and blue curves
r_curve = [i / (i_size - 1) for i in range(i_size)]
g_curve = [i / (i_size - 1) for i in range(i_size)]
b_curve = [i / (i_size - 1) for i in range(i_size)]



clip_result = True
'''
Set to `False` if you want to allow value overflow rather than clipping,
doing so can create visual artifacts
'''


def curves(r, g, b):
    '''
    Generate a tuple of curve–parameter pairs
    
    @param   r  The red parameter
    @param   g  The green parameter
    @param   b  The blue parameter
    @return     `((r_curve, r), (g_curve, g), (b_curve, b))`
    '''
    return ((r_curve, r), (g_curve, g), (b_curve, b))



def series_d(temperature):
    '''
    Calculate the colour for a blackbody temperature
    
    @param   temperature:float       The blackbody temperature in kelvins, must be inside [4000, 7000]
    @return  :(float, float, float)  The red, green and blue components of the white point
    '''
    x = 0
    ks = ((0.244063, 0), (0.09911, 1), (2.9678, 2), (-4.6070, 3))
    if temperature > 7000:
        ks = ((0.237040, 0), (0.24748, 1), (1.9018, 2), (-2.0064, 3))
    for (k, d) in ks:
        x += k * 10 ** (d * 3) / temperature ** d
    y = 2.870 * x - 3.000 * x ** 2 - 0.275
    return ciexy_to_srgb(x, y, 1.0)


def simple_whitepoint(temperature):
    '''
    Calculate the colour for a blackbody temperature using a simple, but inaccurate, algorithm
    
    @param   temperature:float       The blackbody temperature in kelvins, not guaranteed for values outside [1000, 40000]
    @return  :(float, float, float)  The red, green and blue components of the white point
    '''
    r, g, b = 1, 1, 1
    temp = temperature / 100
    if temp > 66:
        temp -= 60
        r = 1.292936186 * temp ** 0.1332047592
        g = 1.129890861 * temp ** -0.0755148492
    else:
        g = 0.390081579 * math.log(temp) - 0.631841444
        if temp <= 19:
            b = 0
        elif temp < 66:
            b = 0.543206789 * math.log(temp - 10) - 1.196254089
    return (r, g, b)


cmf_2deg_cache = None
def cmf_2deg(temperature):
    '''
    Calculate the colour for a blackbody temperature using raw CIE 1931 2 degree CMF data with interpolation
    
    @param   temperature:float       The blackbody temperature in kelvins, clipped to [1000, 40000]
    @return  :(float, float, float)  The red, green and blue components of the white point
    '''
    global cmf_2deg_cache
    if cmf_2deg_cache is None:
        with open(DATADIR + '/2deg', 'rb') as file:
            cmf_2deg_cache = file.read()
        cmf_2deg_cache = cmf_2deg_cache.decode('utf-8', 'error').split('\n')
        cmf_2deg_cache = filter(lambda x : not x == '', cmf_2deg_cache)
        cmf_2deg_cache = [[float(x) for x in x_y.split(' ')] for x_y in cmf_2deg_cache]
    temp = min(max(1000, temperature), 40000)
    x, y = 0, 0
    if (temp % 100) == 0:
        (x, y) = cmf_2deg_cache[(temp - 1000) // 100]
    else:
        temp -= 1000
        (x1, y1) = cmf_2deg_cache[temp // 100]
        (x2, y2) = cmf_2deg_cache[temp // 100 + 1]
        temp = (temp % 100) / 100
        x = x1 * temp + x2 * (1 - temp)
        y = y1 * temp + y2 * (1 - temp)
    return ciexyy_to_srgb(x, y, 1.0)


cmf_10deg_cache = None
def cmf_10deg(temperature):
    '''
    Calculate the colour for a blackbody temperature using raw CIE 1964 10 degree CMF data with interpolation
    
    @param   temperature:float       The blackbody temperature in kelvins, clipped to [1000, 40000]
    @return  :(float, float, float)  The red, green and blue components of the white point
    '''
    global cmf_10deg_cache
    if cmf_10deg_cache is None:
        with open(DATADIR + '/10deg', 'rb') as file:
            cmf_10deg_cache = file.read()
        cmf_10deg_cache = cmf_10deg_cache.decode('utf-8', 'error').split('\n')
        cmf_10deg_cache = filter(lambda x : not x == '', cmf_10deg_cache)
        cmf_10deg_cache = [[float(x) for x in x_y.split(' ')] for x_y in cmf_10deg_cache]
    temp = min(max(1000, temperature), 40000)
    x, y = 0, 0
    if (temp % 100) == 0:
        (x, y) = cmf_10deg_cache[(temp - 1000) // 100]
    else:
        temp -= 1000
        (x1, y1) = cmf_10deg_cache[temp // 100]
        (x2, y2) = cmf_10deg_cache[temp // 100 + 1]
        temp = (temp % 100) / 100
        x = x1 * temp + x2 * (1 - temp)
        y = y1 * temp + y2 * (1 - temp)
    return ciexyy_to_srgb(x, y, 1.0)



def temperature(temperature, algorithm, linear_rgb = True):
    '''
    Change colour temperature according to the CIE illuminant series D
    
    @param  temperature:float                        The blackbody temperature in kelvins
    @param  algorithm:(float)→(float, float, float)  Algorithm for calculating a white point, for example `series_d` or `simple_whitepoint`
    @param  linear_rgb:[bool]                        Whether to use linear RGB, otherwise sRG is used
    '''
    if temperature == 6500:
        return
    (r, g, b) = algorithm(temperature)
    if linear_rgb:
        for curve in (r_curve, g_curve, b_curve):
            for i in range(i_size):
                R, G, B = r_curve[i], g_curve[i], b_curve[i]
                (R, G, B) = standard_to_linear(R, G, B)
                r_curve[i], g_curve[i], b_curve[i] = R, G, B
    rgb_brightness(r, g, b)
    if linear_rgb:
        for curve in (r_curve, g_curve, b_curve):
            for i in range(i_size):
                R, G, B = r_curve[i], g_curve[i], b_curve[i]
                (R, G, B) = linear_to_standard(R, G, B)
                r_curve[i], g_curve[i], b_curve[i] = R, G, B


def divide_by_maximum(rgb):
    '''
    Divide all colour components by the value of the most prominent colour component
    
    @param   rgb:[float, float, float]  The three colour components
    @return  :[float, float, float]     The three colour components divided by the maximum
    '''
    m = max([abs(x) for x in rgb])
    if m != 0:
        return [x / m for x in rgb]
    return rgb


def clip_whitepoint(rgb):
    '''
    Clip all colour components to fit inside [0, 1]
    
    @param   rgb:[float, float, float]  The three colour components
    @return  :[float, float, float]     The three colour components clipped
    '''
    return [min(max(0, x), 1) for x in rgb]


def rgb_contrast(r, g, b):
    '''
    Apply contrast correction on the colour curves using sRGB
    
    @param  r:float  The contrast parameter for the red curve
    @param  g:float  The contrast parameter for the green curve
    @param  b:float  The contrast parameter for the blue curve
    '''
    for (curve, level) in curves(r, g, b):
        if not level == 1.0:
            for i in range(i_size):
                curve[i] = (curve[i] - 0.5) * level + 0.5


def cie_contrast(level):
    '''
    Apply contrast correction on the colour curves using CIE XYZ
    
    @param  level:float  The brightness parameter
    '''
    if not level == 1.0:
        for i in range(i_size):
            (x, y, Y) = srgb_to_ciexyy(r_curve[i], g_curve[i], b_curve[i])
            (r_curve[i], g_curve[i], b_curve[i]) = to_rgb(x, y, (Y - 0.5) * level + 0.5)


def rgb_brightness(r, g, b):
    '''
    Apply brightness correction on the colour curves using sRGB
    
    @param  r:float  The brightness parameter for the red curve
    @param  g:float  The brightness parameter for the green curve
    @param  b:float  The brightness parameter for the blue curve
    '''
    for (curve, level) in curves(r, g, b):
        if not level == 1.0:
            for i in range(i_size):
                curve[i] *= level


def cie_brightness(level):
    '''
    Apply brightness correction on the colour curves using CIE XYZ
    
    @param  level:float  The brightness parameter
    '''
    if not level == 1.0:
        for i in range(i_size):
            (x, y, Y) = srgb_to_ciexyy(r_curve[i], g_curve[i], b_curve[i])
            (r_curve[i], g_curve[i], b_curve[i]) = to_rgb(x, y, Y * level)


def gamma(r, g, b):
    '''
    Apply gamma correction on the colour curves
    
    @param  r:float  The gamma parameter for the red curve
    @param  g:float  The gamma parameter for the green curve
    @param  b:float  The gamma parameter for the blue curve
    '''
    for (curve, level) in curves(r, g, b):
        if not level == 1.0:
            for i in range(i_size):
                curve[i] **= level

    
def negative(r, g, b):
    '''
    Invert the colour curves (negative image)
    
    @param  r:bool  Whether to invert the red curve
    @param  g:bool  Whether to invert the green curve
    @param  b:bool  Whether to invert the blue curve
    '''
    for (curve, setting) in curves(r, g, b):
        if setting:
            for i in range(i_size):
                curve[i] = 1 - curve[i]

    
def sigmoid(r, g, b):
    '''
    Apply S-curve correction on the colour curves
    
    @param  r:float?  The sigmoid parameter for the red curve
    @param  g:float?  The sigmoid parameter for the green curve
    @param  b:float?  The sigmoid parameter for the blue curve
    '''
    for (curve, level) in curves(r, g, b):
        if level is not None:
            for i in range(i_size):
                try:
                    curve[i] = 0.5 - math.log(1 / curve[i] - 1) / level
                except:
                    curve[i] = 0;


def manipulate(r, g = None, b = None):
    '''
    Manipulate the colour curves using a lambda function
    
    @param  r:(float)→float   Lambda function to manipulate the red colour curve
    @param  g:(float)?→float  Lambda function to manipulate the green colour curve, defaults to `r` if `None`
    @param  b:(float)?→float  Lambda function to manipulate the blue colour curve, defaults to `r` if `None`
    
    The lambda functions thats a colour value and maps it to a new colour value.
    For example, if the red value 0.5 is already mapped to 0.25, then if the function
    maps 0.25 to 0.5, the red value 0.5 will revert back to being mapped to 0.5.
    '''
    if g is None:  g = r
    if b is None:  b = r
    for (curve, f) in curves(r, g, b):
        for i in range(i_size):
            curve[i] = f(curve[i])


def start_over():
    '''
    Reverts all colours curves to identity mappings.
    This intended for multi-monitor setups with different curves on each monitor.
    If you have a multi-monitor setups without different curves then you have not
    calibrated the monitors or you have awesome monitors that support hardware
    gamma correction.
    '''
    for i in range(i_size):
        v = i / (i_size - 1)
        r_curve[i] = v
        g_curve[i] = v
        b_curve[i] = v


def clip():
    '''
    Clip all values below the actual minimum and above actual maximums
    '''
    for curve in (r_curve, g_curve, b_curve):
        for i in range(i_size):
            curve[i] = min(max(0.0, curve[i]), 1.0)