summaryrefslogtreecommitdiff
path: root/src/ipa/rkisp1/algorithms/awb.cpp
blob: 59664d09b84c6ed3b877e0e8d809c8caa00d4cb7 (plain)
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
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
/* 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 <iomanip>

#include <libcamera/base/log.h>

#include <libcamera/control_ids.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)

Awb::Awb()
	: rgbMode_(false)
{
}

/**
 * \copydoc libcamera::ipa::Algorithm::configure
 */
int Awb::configure(IPAContext &context,
		   const IPACameraSensorInfo &configInfo)
{
	context.activeState.awb.gains.manual.red = 1.0;
	context.activeState.awb.gains.manual.blue = 1.0;
	context.activeState.awb.gains.manual.green = 1.0;
	context.activeState.awb.gains.automatic.red = 1.0;
	context.activeState.awb.gains.automatic.blue = 1.0;
	context.activeState.awb.gains.automatic.green = 1.0;
	context.activeState.awb.autoEnabled = true;

	/*
	 * 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;

	context.configuration.awb.enabled = true;

	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, const uint32_t frame,
		  IPAFrameContext &frameContext, rkisp1_params_cfg *params)
{
	/*
	 * This is the latest time we can read the active state. This is the
	 * most up-to-date automatic values we can read.
	 */
	if (frameContext.awb.autoEnabled) {
		frameContext.awb.gains.red = context.activeState.awb.gains.automatic.red;
		frameContext.awb.gains.green = context.activeState.awb.gains.automatic.green;
		frameContext.awb.gains.blue = context.activeState.awb.gains.automatic.blue;
	}

	params->others.awb_gain_config.gain_green_b = 256 * frameContext.awb.gains.green;
	params->others.awb_gain_config.gain_blue = 256 * frameContext.awb.gains.blue;
	params->others.awb_gain_config.gain_red = 256 * frameContext.awb.gains.red;
	params->others.awb_gain_config.gain_green_r = 256 * frameContext.awb.gains.green;

	/* Update the gains. */
	params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;

	/* If we have already set the AWB measurement parameters, return. */
	if (frame > 0)
		return;

	rkisp1_cif_isp_awb_meas_config &awb_config = params->meas.awb_meas_config;

	/* Configure the measure window for AWB. */
	awb_config.awb_wnd = context.configuration.awb.measureWindow;

	/* Number of frames to use to estimate the means (0 means 1 frame). */
	awb_config.frames = 0;

	/* Select RGB or YCbCr means measurement. */
	if (rgbMode_) {
		awb_config.awb_mode = RKISP1_CIF_ISP_AWB_MODE_RGB;

		/*
		 * For RGB-based measurements, pixels are selected with maximum
		 * red, green and blue thresholds that are set in the
		 * awb_ref_cr, awb_min_y and awb_ref_cb respectively. The other
		 * values are not used, set them to 0.
		 */
		awb_config.awb_ref_cr = 250;
		awb_config.min_y = 250;
		awb_config.awb_ref_cb = 250;

		awb_config.max_y = 0;
		awb_config.min_c = 0;
		awb_config.max_csum = 0;
	} else {
		awb_config.awb_mode = RKISP1_CIF_ISP_AWB_MODE_YCBCR;

		/* Set the reference Cr and Cb (AWB target) to white. */
		awb_config.awb_ref_cb = 128;
		awb_config.awb_ref_cr = 128;

		/*
		 * Filter out pixels based on luminance and chrominance values.
		 * The acceptable luma values are specified as a [16, 250]
		 * range, while the acceptable chroma values are specified with
		 * a minimum of 16 and a maximum Cb+Cr sum of 250.
		 */
		awb_config.min_y = 16;
		awb_config.max_y = 250;
		awb_config.min_c = 16;
		awb_config.max_csum = 250;
	}

	/* Enable the AWB gains. */
	params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
	params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;

	/* Update the AWB measurement parameters and enable the AWB module. */
	params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB;
	params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB;
	params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB;
}

/**
 * \copydoc libcamera::ipa::Algorithm::queueRequest
 */
void Awb::queueRequest(IPAContext &context,
		       [[maybe_unused]] const uint32_t frame,
		       IPAFrameContext &frameContext,
		       const ControlList &controls)
{
	auto &awb = context.activeState.awb;

	const auto &awbEnable = controls.get(controls::AwbEnable);
	if (awbEnable && *awbEnable != awb.autoEnabled) {
		awb.autoEnabled = *awbEnable;

		LOG(RkISP1Awb, Debug)
			<< (*awbEnable ? "Enabling" : "Disabling") << " AWB";
	}

	const auto &colourGains = controls.get(controls::ColourGains);
	if (colourGains && !awb.autoEnabled) {
		awb.gains.manual.red = (*colourGains)[0];
		awb.gains.manual.blue = (*colourGains)[1];

		LOG(RkISP1Awb, Debug)
			<< "Set colour gains to red: " << awb.gains.manual.red
			<< ", blue: " << awb.gains.manual.blue;
	}

	frameContext.awb.autoEnabled = awb.autoEnabled;

	if (!awb.autoEnabled) {
		frameContext.awb.gains.red = awb.gains.manual.red;
		frameContext.awb.gains.green = 1.0;
		frameContext.awb.gains.blue = awb.gains.manual.blue;
	}
}

/**
 * \copydoc libcamera::ipa::Algorithm::process
 */
void Awb::process(IPAContext &context,
		  [[maybe_unused]] const uint32_t frame,
		  IPAFrameContext &frameContext,
		  const rkisp1_stat_buffer *stats)
{
	const rkisp1_cif_isp_stat *params = &stats->params;
	const rkisp1_cif_isp_awb_stat *awb = &params->awb;
	IPAActiveState &activeState = context.activeState;
	double greenMean;
	double redMean;
	double blueMean;

	if (rgbMode_) {
		greenMean = awb->awb_mean[0].mean_y_or_g;
		redMean = awb->awb_mean[0].mean_cr_or_r;
		blueMean = awb->awb_mean[0].mean_cb_or_b;
	} else {
		/* Get the YCbCr mean values */
		double yMean = awb->awb_mean[0].mean_y_or_g;
		double cbMean = awb->awb_mean[0].mean_cb_or_b;
		double crMean = awb->awb_mean[0].mean_cr_or_r;

		/*
		 * 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;
		redMean = 1.1636 * yMean - 0.0623 * cbMean + 1.6008 * crMean;
		greenMean = 1.1636 * yMean - 0.4045 * cbMean - 0.7949 * crMean;
		blueMean = 1.1636 * yMean + 1.9912 * cbMean - 0.0250 * crMean;

		/*
		 * Due to hardware rounding errors in the YCbCr means, the
		 * calculated RGB means may be negative. This would lead to
		 * negative gains, messing up calculation. Prevent this by
		 * clamping the means to positive values.
		 */
		redMean = std::max(redMean, 0.0);
		greenMean = std::max(greenMean, 0.0);
		blueMean = std::max(blueMean, 0.0);
	}

	/*
	 * The ISP computes the AWB means after applying the colour gains,
	 * divide by the gains that were used to get the raw means from the
	 * sensor.
	 */
	redMean /= frameContext.awb.gains.red;
	greenMean /= frameContext.awb.gains.green;
	blueMean /= frameContext.awb.gains.blue;

	frameContext.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);

	/* 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) * activeState.awb.gains.automatic.red;
	blueGain = speed * blueGain + (1 - speed) * activeState.awb.gains.automatic.blue;

	/*
	 * Gain values are unsigned integer value, range 0 to 4 with 8 bit
	 * fractional part. Hardcode the green gain to 1.0.
	 */
	activeState.awb.gains.automatic.red = std::clamp(redGain, 0.0, 1023.0 / 256);
	activeState.awb.gains.automatic.blue = std::clamp(blueGain, 0.0, 1023.0 / 256);
	activeState.awb.gains.automatic.green = 1.0;

	LOG(RkISP1Awb, Debug) << std::showpoint
		<< "Means [" << redMean << ", " << greenMean << ", " << blueMean
		<< "], gains [" << activeState.awb.gains.automatic.red << ", "
		<< activeState.awb.gains.automatic.green << ", "
		<< activeState.awb.gains.automatic.blue << "], temp "
		<< frameContext.awb.temperatureK << "K";
}

REGISTER_IPA_ALGORITHM(Awb, "Awb")

} /* namespace ipa::rkisp1::algorithms */

} /* namespace libcamera */