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# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (C) 2019, Raspberry Pi (Trading) Limited
#
# ctt_ccm.py - camera tuning tool for CCM (colour correction matrix)
from ctt_image_load import *
from ctt_awb import get_alsc_patches
"""
takes 8-bit macbeth chart values, degammas and returns 16 bit
"""
def degamma(x):
x = x / ((2**8)-1)
x = np.where(x < 0.04045, x/12.92, ((x+0.055)/1.055)**2.4)
x = x * ((2**16)-1)
return x
"""
FInds colour correction matrices for list of images
"""
def ccm(Cam, cal_cr_list, cal_cb_list):
imgs = Cam.imgs
"""
standard macbeth chart colour values
"""
m_rgb = np.array([ # these are in sRGB
[116, 81, 67], # dark skin
[199, 147, 129], # light skin
[91, 122, 156], # blue sky
[90, 108, 64], # foliage
[130, 128, 176], # blue flower
[92, 190, 172], # bluish green
[224, 124, 47], # orange
[68, 91, 170], # purplish blue
[198, 82, 97], # moderate red
[94, 58, 106], # purple
[159, 189, 63], # yellow green
[230, 162, 39], # orange yellow
[35, 63, 147], # blue
[67, 149, 74], # green
[180, 49, 57], # red
[238, 198, 20], # yellow
[193, 84, 151], # magenta
[0, 136, 170], # cyan (goes out of gamut)
[245, 245, 243], # white 9.5
[200, 202, 202], # neutral 8
[161, 163, 163], # neutral 6.5
[121, 121, 122], # neutral 5
[82, 84, 86], # neutral 3.5
[49, 49, 51] # black 2
])
"""
convert reference colours from srgb to rgb
"""
m_srgb = degamma(m_rgb)
"""
reorder reference values to match how patches are ordered
"""
m_srgb = np.array([m_srgb[i::6] for i in range(6)]).reshape((24, 3))
"""
reformat alsc correction tables or set colour_cals to None if alsc is
deactivated
"""
if cal_cr_list is None:
colour_cals = None
else:
colour_cals = {}
for cr, cb in zip(cal_cr_list, cal_cb_list):
cr_tab = cr['table']
cb_tab = cb['table']
"""
normalise tables so min value is 1
"""ss="hl num">0.055) * 255 for colour in x]
"""
FInds colour correction matrices for list of images
"""
def ccm(Cam, cal_cr_list, cal_cb_list):
global matrix_selection_types, typenum
imgs = Cam.imgs
"""
standard macbeth chart colour values
"""
m_rgb = np.array([ # these are in RGB
[116, 81, 67], # dark skin
[199, 147, 129], # light skin
[91, 122, 156], # blue sky
[90, 108, 64], # foliage
[130, 128, 176], # blue flower
[92, 190, 172], # bluish green
[224, 124, 47], # orange
[68, 91, 170], # purplish blue
[198, 82, 97], # moderate red
[94, 58, 106], # purple
[159, 189, 63], # yellow green
[230, 162, 39], # orange yellow
[35, 63, 147], # blue
[67, 149, 74], # green
[180, 49, 57], # red
[238, 198, 20], # yellow
[193, 84, 151], # magenta
[0, 136, 170], # cyan (goes out of gamut)
[245, 245, 243], # white 9.5
[200, 202, 202], # neutral 8
[161, 163, 163], # neutral 6.5
[121, 121, 122], # neutral 5
[82, 84, 86], # neutral 3.5
[49, 49, 51] # black 2
])
"""
convert reference colours from srgb to rgb
"""
m_srgb = degamma(m_rgb) # now in 16 bit color.
# Produce array of LAB values for ideal color chart
m_lab = [colors.RGB_to_LAB(color / 256) for color in m_srgb]
"""
reorder reference values to match how patches are ordered
"""
m_srgb = np.array([m_srgb[i::6] for i in range(6)]).reshape((24, 3))
m_lab = np.array([m_lab[i::6] for i in range(6)]).reshape((24, 3))
m_rgb = np.array([m_rgb[i::6] for i in range(6)]).reshape((24, 3))
"""
reformat alsc correction tables or set colour_cals to None if alsc is
deactivated
"""
if cal_cr_list is None:
colour_cals = None
else:
colour_cals = {}
for cr, cb in zip(cal_cr_list, cal_cb_list):
cr_tab = cr['table']
cb_tab = cb['table']
"""
normalise tables so min value is 1
"""
cr_tab = cr_tab / np.min(cr_tab)
cb_tab = cb_tab / np.min(cb_tab)
colour_cals[cr['ct']] = [cr_tab, cb_tab]
"""
for each image, perform awb and alsc corrections.
Then calculate the colour correction matrix for that image, recording the
ccm and the colour tempertaure.
"""
ccm_tab = {}
for Img in imgs:
Cam.log += '\nProcessing image: ' + Img.name
"""
get macbeth patches with alsc applied if alsc enabled.
Note: if alsc is disabled then colour_cals will be set to None and no
the function will simply return the macbeth patches
"""
r, b, g = get_alsc_patches(Img, colour_cals, grey=False)
# 256 values for each patch of sRGB values
"""
do awb
Note: awb is done by measuring the macbeth chart in the image, rather
than from the awb calibration. This is done so the awb will be perfect
and the ccm matrices will be more accurate.
"""
r_greys, b_greys, g_greys = r[3::4], b[3::4], g[3::4]
r_g = np.mean(r_greys / g_greys)
b_g = np.mean(b_greys / g_greys)
r = r / r_g
b = b / b_g
"""
normalise brightness wrt reference macbeth colours and then average
each channel for each patch
"""
gain = np.mean(m_srgb) / np.mean((r, g, b))
Cam.log += '\nGain with respect to standard colours: {:.3f}'.format(gain)
r = np.mean(gain * r, axis=1)
b = np.mean(gain * b, axis=1)
g = np.mean(gain * g, axis=1)
"""
calculate ccm matrix
"""
# ==== All of below should in sRGB ===##
sumde = 0
ccm = do_ccm(r, g, b, m_srgb)
# This is the initial guess that our optimisation code works with.
original_ccm = ccm
r1 = ccm[0]
r2 = ccm[1]
g1 = ccm[3]
g2 = ccm[4]
b1 = ccm[6]
b2 = ccm[7]
'''
COLOR MATRIX LOOKS AS BELOW
R1 R2 R3 Rval Outr
G1 G2 G3 * Gval = G
B1 B2 B3 Bval B
Will be optimising 6 elements and working out the third element using 1-r1-r2 = r3
'''
x0 = [r1, r2, g1, g2, b1, b2]
'''
We use our old CCM as the initial guess for the program to find the
optimised matrix
'''
result = minimize(guess, x0, args=(r, g, b, m_lab), tol=0.01)
'''
This produces a color matrix which has the lowest delta E possible,
based off the input data. Note it is impossible for this to reach
zero since the input data is imperfect
'''
Cam.log += ("\n \n Optimised Matrix Below: \n \n")
[r1, r2, g1, g2, b1, b2] = result.x
# The new, optimised color correction matrix values
optimised_ccm = [r1, r2, (1 - r1 - r2), g1, g2, (1 - g1 - g2), b1, b2, (1 - b1 - b2)]
# This is the optimised Color Matrix (preserving greys by summing rows up to 1)
Cam.log += str(optimised_ccm)
Cam.log += "\n Old Color Correction Matrix Below \n"
Cam.log += str(ccm)
formatted_ccm = np.array(original_ccm).reshape((3, 3))
'''
below is a whole load of code that then applies the latest color
matrix, and returns LAB values for color. This can then be used
to calculate the final delta E
'''
optimised_ccm_rgb = [] # Original Color Corrected Matrix RGB / LAB
optimised_ccm_lab = []
formatted_optimised_ccm = np.array(optimised_ccm).reshape((3, 3))
after_gamma_rgb = []
after_gamma_lab = []
for RGB in zip(r, g, b):
ccm_applied_rgb = np.dot(formatted_ccm, (np.array(RGB) / 256))
optimised_ccm_rgb.append(gamma(ccm_applied_rgb))
optimised_ccm_lab.append(colors.RGB_to_LAB(ccm_applied_rgb))
optimised_ccm_applied_rgb = np.dot(formatted_optimised_ccm, np.array(RGB) / 256)
after_gamma_rgb.append(gamma(optimised_ccm_applied_rgb))
after_gamma_lab.append(colors.RGB_to_LAB(optimised_ccm_applied_rgb))
'''
Gamma After RGB / LAB - not used in calculations, only used for visualisation
We now want to spit out some data that shows
how the optimisation has improved the color matrices
'''
Cam.log += "Here are the Improvements"
# CALCULATE WORST CASE delta e
old_worst_delta_e = 0
before_average = transform_and_evaluate(formatted_ccm, r, g, b, m_lab)
new_worst_delta_e = 0
after_average = transform_and_evaluate(formatted_optimised_ccm, r, g, b, m_lab)
for i in range(24):
old_delta_e = deltae(optimised_ccm_lab[i], m_lab[i]) # Current Old Delta E
new_delta_e = deltae(after_gamma_lab[i], m_lab[i]) # Current New Delta E
if old_delta_e > old_worst_delta_e:
old_worst_delta_e = old_delta_e
if new_delta_e > new_worst_delta_e:
new_worst_delta_e = new_delta_e
Cam.log += "Before color correction matrix was optimised, we got an average delta E of " + str(before_average) + " and a maximum delta E of " + str(old_worst_delta_e)
Cam.log += "After color correction matrix was optimised, we got an average delta E of " + str(after_average) + " and a maximum delta E of " + str(new_worst_delta_e)
visualise_macbeth_chart(m_rgb, optimised_ccm_rgb, after_gamma_rgb, str(Img.col) + str(matrix_selection_types[typenum]))
'''
The program will also save some visualisations of improvements.
Very pretty to look at. Top rectangle is ideal, Left square is
before optimisation, right square is after.
'''
"""
if a ccm has already been calculated for that temperature then don't
overwrite but save both. They will then be averaged later on
""" # Now going to use optimised color matrix, optimised_ccm
if Img.col in ccm_tab.keys():
ccm_tab[Img.col].append(optimised_ccm)
else:
ccm_tab[Img.col] = [optimised_ccm]
Cam.log += '\n'
Cam.log += '\nFinished processing images'
"""
average any ccms that share a colour temperature
"""
for k, v in ccm_tab.items():
tab = np.mean(v, axis=0)
tab = np.where((10000 * tab) % 1 <= 0.05, tab + 0.00001, tab)
tab = np.where((10000 * tab) % 1 >= 0.95, tab - 0.00001, tab)
ccm_tab[k] = list(np.round(tab, 5))
Cam.log += '\nMatrix calculated for colour temperature of {} K'.format(k)
"""
return all ccms with respective colour temperature in the correct format,
sorted by their colour temperature
"""
sorted_ccms = sorted(ccm_tab.items(), key=lambda kv: kv[0])
ccms = []
for i in sorted_ccms:
ccms.append({
'ct': i[0],
'ccm': i[1]
})
return ccms
def guess(x0, r, g, b, m_lab): # provides a method of numerical feedback for the optimisation code
[r1, r2, g1, g2, b1, b2] = x0
ccm = np.array([r1, r2, (1 - r1 - r2),
g1, g2, (1 - g1 - g2),
b1, b2, (1 - b1 - b2)]).reshape((3, 3)) # format the matrix correctly
return transform_and_evaluate(ccm, r, g, b, m_lab)
def transform_and_evaluate(ccm, r, g, b, m_lab): # Transforms colors to LAB and applies the correction matrix
# create list of matrix changed colors
realrgb = []
for RGB in zip(r, g, b):
rgb_post_ccm = np.dot(ccm, np.array(RGB) / 256) # This is RGB values after the color correction matrix has been applied
realrgb.append(colors.RGB_to_LAB(rgb_post_ccm))
# now compare that with m_lab and return numeric result, averaged for each patch
return (sumde(realrgb, m_lab) / 24) # returns an average result of delta E
def sumde(listA, listB):
global typenum, test_patches
sumde = 0
maxde = 0
patchde = [] # Create array of the delta E values for each patch. useful for optimisation of certain patches
for listA_item, listB_item in zip(listA, listB):
if maxde < (deltae(listA_item, listB_item)):
maxde = deltae(listA_item, listB_item)
patchde.append(deltae(listA_item, listB_item))
sumde += deltae(listA_item, listB_item)
'''
The different options specified at the start allow for
the maximum to be returned, average or specific patches
'''
if typenum == 0:
return sumde
if typenum == 1:
return maxde
if typenum == 2:
output = sum([patchde[test_patch] for test_patch in test_patches])
# Selects only certain patches and returns the output for them
return output
"""
calculates the ccm for an individual image.
ccms are calculated in rgb space, and are fit by hand. Although it is a 3x3
matrix, each row must add up to 1 in order to conserve greyness, simplifying
calculation.
The initial CCM is calculated in RGB, and then optimised in LAB color space
This simplifies the initial calculation but then gets us the accuracy of
using LAB color space.
"""
def do_ccm(r, g, b, m_srgb):
rb = r-b
gb = g-b
rb_2s = (rb * rb)
rb_gbs = (rb * gb)
gb_2s = (gb * gb)
r_rbs = rb * (m_srgb[..., 0] - b)
r_gbs = gb * (m_srgb[..., 0] - b)
g_rbs = rb * (m_srgb[..., 1] - b)
g_gbs = gb * (m_srgb[..., 1] - b)
b_rbs = rb * (m_srgb[..., 2] - b)
b_gbs = gb * (m_srgb[..., 2] - b)
"""
Obtain least squares fit
"""
rb_2 = np.sum(rb_2s)
gb_2 = np.sum(gb_2s)
rb_gb = np.sum(rb_gbs)
r_rb = np.sum(r_rbs)
r_gb = np.sum(r_gbs)
g_rb = np.sum(g_rbs)
g_gb = np.sum(g_gbs)
b_rb = np.sum(b_rbs)
b_gb = np.sum(b_gbs)
det = rb_2 * gb_2 - rb_gb * rb_gb
"""
Raise error if matrix is singular...
This shouldn't really happen with real data but if it does just take new
pictures and try again, not much else to be done unfortunately...
"""
if det < 0.001:
raise ArithmeticError
r_a = (gb_2 * r_rb - rb_gb * r_gb) / det
r_b = (rb_2 * r_gb - rb_gb * r_rb) / det
"""
Last row can be calculated by knowing the sum must be 1
"""
r_c = 1 - r_a - r_b
g_a = (gb_2 * g_rb - rb_gb * g_gb) / det
g_b = (rb_2 * g_gb - rb_gb * g_rb) / det
g_c = 1 - g_a - g_b
b_a = (gb_2 * b_rb - rb_gb * b_gb) / det
b_b = (rb_2 * b_gb - rb_gb * b_rb) / det
b_c = 1 - b_a - b_b
"""
format ccm
"""
ccm = [r_a, r_b, r_c, g_a, g_b, g_c, b_a, b_b, b_c]
return ccm
def deltae(colorA, colorB):
return ((colorA[0] - colorB[0]) ** 2 + (colorA[1] - colorB[1]) ** 2 + (colorA[2] - colorB[2]) ** 2) ** 0.5
# return ((colorA[1]-colorB[1]) * * 2 + (colorA[2]-colorB[2]) * * 2) * * 0.5
# UNCOMMENT IF YOU WANT TO NEGLECT LUMINANCE FROM CALCULATION OF DELTA E
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