1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2021-2022, Ideas On Board
*
* awb.cpp - AWB control algorithm
*/
#include "awb.h"
#include <algorithm>
#include <cmath>
#include <libcamera/base/log.h>
#include <libcamera/ipa/core_ipa_interface.h>
/**
* \file awb.h
*/
namespace libcamera {
namespace ipa::rkisp1::algorithms {
/**
* \class Awb
* \brief A Grey world white balance correction algorithm
*/
LOG_DEFINE_CATEGORY(RkISP1Awb)
/**
* \copydoc libcamera::ipa::Algorithm::configure
*/
int Awb::configure(IPAContext &context,
const IPACameraSensorInfo &configInfo)
{
context.frameContext.awb.gains.red = 1.0;
context.frameContext.awb.gains.blue = 1.0;
context.frameContext.awb.gains.green = 1.0;
/*
* Define the measurement window for AWB as a centered rectangle
* covering 3/4 of the image width and height.
*/
context.configuration.awb.measureWindow.h_offs = configInfo.outputSize.width / 8;
context.configuration.awb.measureWindow.v_offs = configInfo.outputSize.height / 8;
context.configuration.awb.measureWindow.h_size = 3 * configInfo.outputSize.width / 4;
context.configuration.awb.measureWindow.v_size = 3 * configInfo.outputSize.height / 4;
return 0;
}
uint32_t Awb::estimateCCT(double red, double green, double blue)
{
/* Convert the RGB values to CIE tristimulus values (XYZ) */
double X = (-0.14282) * (red) + (1.54924) * (green) + (-0.95641) * (blue);
double Y = (-0.32466) * (red) + (1.57837) * (green) + (-0.73191) * (blue);
double Z = (-0.68202) * (red) + (0.77073) * (green) + (0.56332) * (blue);
/* Calculate the normalized chromaticity values */
double x = X / (X + Y + Z);
double y = Y / (X + Y + Z);
/* Calculate CCT */
double n = (x - 0.3320) / (0.1858 - y);
return 449 * n * n * n + 3525 * n * n + 6823.3 * n + 5520.33;
}
/**
* \copydoc libcamera::ipa::Algorithm::prepare
*/
void Awb::prepare(IPAContext &context, rkisp1_params_cfg *params)
{
params->others.awb_gain_config.gain_green_b = 256 * context.frameContext.awb.gains.green;
params->others.awb_gain_config.gain_blue = 256 * context.frameContext.awb.gains.blue;
params->others.awb_gain_config.gain_red = 256 * context.frameContext.awb.gains.red;
params->others.awb_gain_config.gain_green_r = 256 * context.frameContext.awb.gains.green;
/* Update the gains. */
params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
/* If we already have configured the gains and window, return. */
if (context.frameContext.frameCount > 0)
return;
/* Configure the gains to apply. */
params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
/* Update the ISP to apply the gains configured. */
params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
/* Configure the measure window for AWB. */
params->meas.awb_meas_config.awb_wnd = context.configuration.awb.measureWindow;
/*
* Measure Y, Cr and Cb means.
* \todo RGB is not working, the kernel seems to not configure it ?
*/
params->meas.awb_meas_config.awb_mode = RKISP1_CIF_ISP_AWB_MODE_YCBCR;
/* Reference Cr and Cb. */
params->meas.awb_meas_config.awb_ref_cb = 128;
params->meas.awb_meas_config.awb_ref_cr = 128;
/* Y values to include are between min_y and max_y only. */
params->meas.awb_meas_config.min_y = 16;
params->meas.awb_meas_config.max_y = 250;
/* Maximum Cr+Cb value to take into account for awb. */
params->meas.awb_meas_config.max_csum = 250;
/* Minimum Cr and Cb values to take into account. */
params->meas.awb_meas_config.min_c = 16;
/* Number of frames to use to estimate the mean (0 means 1 frame). */
params->meas.awb_meas_config.frames = 0;
/* Update AWB measurement unit configuration. */
params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB;
/* Make sure the ISP is measuring the means for the next frame. */
params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB;
params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB;
}
/**
* \copydoc libcamera::ipa::Algorithm::process
*/
void Awb::process([[maybe_unused]] IPAContext &context,
[[maybe_unused]] IPAFrameContext *frameCtx,
const rkisp1_stat_buffer *stats)
{
const rkisp1_cif_isp_stat *params = &stats->params;
const rkisp1_cif_isp_awb_stat *awb = ¶ms->awb;
IPAFrameContext &frameContext = context.frameContext;
/* Get the YCbCr mean values */
double yMean = awb->awb_mean[0].mean_y_or_g;
double crMean = awb->awb_mean[0].mean_cr_or_r;
double cbMean = awb->awb_mean[0].mean_cb_or_b;
/*
* Convert from YCbCr to RGB.
* The hardware uses the following formulas:
* Y = 16 + 0.2500 R + 0.5000 G + 0.1094 B
* Cb = 128 - 0.1406 R - 0.2969 G + 0.4375 B
* Cr = 128 + 0.4375 R - 0.3750 G - 0.0625 B
*
* The inverse matrix is thus:
* [[1,1636, -0,0623, 1,6008]
* [1,1636, -0,4045, -0,7949]
* [1,1636, 1,9912, -0,0250]]
*/
yMean -= 16;
cbMean -= 128;
crMean -= 128;
double redMean = 1.1636 * yMean - 0.0623 * cbMean + 1.6008 * crMean;
double greenMean = 1.1636 * yMean - 0.4045 * cbMean - 0.7949 * crMean;
double blueMean = 1.1636 * yMean + 1.9912 * cbMean - 0.0250 * crMean;
/* Estimate the red and blue gains to apply in a grey world. */
double redGain = greenMean / (redMean + 1);
double blueGain = greenMean / (blueMean + 1);
/* Filter the values to avoid oscillations. */
double speed = 0.2;
redGain = speed * redGain + (1 - speed) * frameContext.awb.gains.red;
blueGain = speed * blueGain + (1 - speed) * frameContext.awb.gains.blue;
/*
* Gain values are unsigned integer value, range 0 to 4 with 8 bit
* fractional part.
*/
frameContext.awb.gains.red = std::clamp(redGain, 0.0, 1023.0 / 256);
frameContext.awb.gains.blue = std::clamp(blueGain, 0.0, 1023.0 / 256);
/* Hardcode the green gain to 1.0. */
frameContext.awb.gains.green = 1.0;
frameContext.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);
LOG(RkISP1Awb, Debug) << "Gain found for red: " << context.frameContext.awb.gains.red
<< " and for blue: " << context.frameContext.awb.gains.blue;
}
REGISTER_IPA_ALGORITHM(Awb, "Awb")
} /* namespace ipa::rkisp1::algorithms */
} /* namespace libcamera */
|
