src/ipa/libipa/camera_sensor_helper.cpp


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
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2021, Google Inc.
 *
 * camera_sensor_helper.cpp - Helper class that performs sensor-specific
 * parameter computations
 */
#include "camera_sensor_helper.h"

#include <libcamera/base/log.h>

/**
 * \file camera_sensor_helper.h
 * \brief Helper class that performs sensor-specific parameter computations
 *
 * Computation of sensor configuration parameters is a sensor specific
 * operation. Each CameraHelper derived class computes the value of
 * configuration parameters, for example the analogue gain value, using
 * sensor-specific functions and constants.
 *
 * Every subclass of CameraSensorHelper shall be registered with libipa using
 * the REGISTER_CAMERA_SENSOR_HELPER() macro.
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(CameraSensorHelper)

namespace ipa {

/**
 * \class CameraSensorHelper
 * \brief Base class for computing sensor tuning parameters using
 * sensor-specific constants
 *
 * Instances derived from CameraSensorHelper class are sensor-specific.
 * Each supported sensor will have an associated base class defined.
 */

/**
 * \brief Construct a CameraSensorHelper instance
 *
 * CameraSensorHelper derived class instances shall never be constructed
 * manually but always through the CameraSensorHelperFactory::create() function.
 */

/**
 * \brief Compute gain code from the analogue gain absolute value
 * \param[in] gain The real gain to pass
 *
 * This function aims to abstract the calculation of the gain letting the IPA
 * use the real gain for its estimations.
 *
 * The parameters come from the MIPI Alliance Camera Specification for
 * Camera Command Set (CCS).
 *
 * \return The gain code to pass to V4L2
 */
uint32_t CameraSensorHelper::gainCode(double gain) const
{
	ASSERT(analogueGainConstants_.m0 == 0 || analogueGainConstants_.m1 == 0);
	ASSERT(analogueGainConstants_.type == AnalogueGainLinear);

	return (analogueGainConstants_.c0 - analogueGainConstants_.c1 * gain) /
	       (analogueGainConstants_.m1 * gain - analogueGainConstants_.m0);
}

/**
 * \brief Compute the real gain from the V4L2 subdev control gain code
 * \param[in] gainCode The V4L2 subdev control gain
 *
 * This function aims to abstract the calculation of the gain letting the IPA
 * use the real gain for its estimations. It is the counterpart of the function
 * CameraSensorHelper::gainCode.
 *
 * The parameters come from the MIPI Alliance Camera Specification for
 * Camera Command Set (CCS).
 *
 * \return The real gain
 */
double CameraSensorHelper::gain(uint32_t gainCode) const
{
	ASSERT(analogueGainConstants_.m0 == 0 || analogueGainConstants_.m1 == 0);
	ASSERT(analogueGainConstants_.type == AnalogueGainLinear);

	return (analogueGainConstants_.m0 * static_cast<double>(gainCode) + analogueGainConstants_.c0) /
	       (analogueGainConstants_.m1 * static_cast<double>(gainCode) + analogueGainConstants_.c1);
}

/**
 * \enum CameraSensorHelper::AnalogueGainType
 * \brief The gain calculation modes as defined by the MIPI CCS
 *
 * Describes the image sensor analogue gain capabilities.
 * Two modes are possible, depending on the sensor: Linear and Exponential.
 */

/**
 * \var CameraSensorHelper::AnalogueGainLinear
 * \brief Gain is computed using linear gain estimation
 *
 * The relationship between the integer gain parameter and the resulting gain
 * multiplier is given by the following equation:
 *
 * \f$gain=\frac{m0x+c0}{m1x+c1}\f$
 *
 * Where 'x' is the gain control parameter, and m0, m1, c0 and c1 are
 * image-sensor-specific constants of the sensor.
 * These constants are static parameters, and for any given image sensor either
 * m0 or m1 shall be zero.
 *
 * The full Gain equation therefore reduces to either:
 *
 * \f$gain=\frac{c0}{m1x+c1}\f$ or \f$\frac{m0x+c0}{c1}\f$
 */

/**
 * \var CameraSensorHelper::AnalogueGainExponential
 * \brief Gain is computed using exponential gain estimation
 * (introduced in CCS v1.1)
 *
 * Starting with CCS v1.1, Alternate Global Analogue Gain is also available.
 * If the image sensor supports it, then the global analogue gain can be
 * controlled by linear and exponential gain formula:
 *
 * \f$gain = analogLinearGainGlobal * 2^{analogExponentialGainGlobal}\f$
 * \todo not implemented in libipa
 */

/**
 * \struct CameraSensorHelper::AnalogueGainConstants
 * \brief Analogue gain constants used for gain calculation
 */

/**
 * \var CameraSensorHelper::AnalogueGainConstants::type
 * \brief Analogue gain calculation mode
 */

/**
 * \var CameraSensorHelper::AnalogueGainConstants::m0
 * \brief Constant used in the analogue Gain coding/decoding
 *
 * \note Either m0 or m1 shall be zero.
 */

/**
 * \var CameraSensorHelper::AnalogueGainConstants::c0
 * \brief Constant used in the analogue gain coding/decoding
 */

/**
 * \var CameraSensorHelper::AnalogueGainConstants::m1
 * \brief Constant used in the analogue gain coding/decoding
 *
 * \note Either m0 or m1 shall be zero.
 */

/**
 * \var CameraSensorHelper::AnalogueGainConstants::c1
 * \brief Constant used in the analogue gain coding/decoding
 */

/**
 * \var CameraSensorHelper::analogueGainConstants_
 * \brief The analogue gain parameters used for calculation
 *
 * The analogue gain is calculated through a formula, and its parameters are
 * sensor specific. Use this variable to store the values at init time.
 */

/**
 * \class CameraSensorHelperFactory
 * \brief Registration of CameraSensorHelperFactory classes and creation of instances
 *
 * To facilitate discovery and instantiation of CameraSensorHelper classes, the
 * CameraSensorHelperFactory class maintains a registry of camera sensor helper
 * sub-classes. Each CameraSensorHelper subclass shall register itself using the
 * REGISTER_CAMERA_SENSOR_HELPER() macro, which will create a corresponding
 * instance of a CameraSensorHelperFactory subclass and register it with the
 * static list of factories.
 */

/**
 * \brief Construct a camera sensor helper factory
 * \param[in] name Name of the camera sensor helper class
 *
 * Creating an instance of the factory registers it with the global list of
 * factories, accessible through the factories() function.
 *
 * The factory \a name is used for debug purpose and shall be unique.
 */
CameraSensorHelperFactory::CameraSensorHelperFactory(const std::string name)
	: name_(name)
{
	registerType(this);
}

/**
 * \brief Create an instance of the CameraSensorHelper corresponding to
 * a named factory
 * \param[in] name Name of the factory
 *
 * \return A unique pointer to a new instance of the CameraSensorHelper subclass
 * corresponding to the named factory or a null pointer if no such factory
 * exists
 */
std::unique_ptr<CameraSensorHelper> CameraSensorHelperFactory::create(const std::string &name)
{
	std::vector<CameraSensorHelperFactory *> &factories =
		CameraSensorHelperFactory::factories();

	for (CameraSensorHelperFactory *factory : factories) {
		if (name != factory->name_)
			continue;

		CameraSensorHelper *helper = factory->createInstance();
		return std::unique_ptr<CameraSensorHelper>(helper);
	}

	return nullptr;
}

/**
 * \brief Add a camera sensor helper class to the registry
 * \param[in] factory Factory to use to construct the camera sensor helper
 *
 * The caller is responsible to guarantee the uniqueness of the camera sensor
 * helper name.
 */
void CameraSensorHelperFactory::registerType(CameraSensorHelperFactory *factory)
{
	std::vector<CameraSensorHelperFactory *> &factories =
		CameraSensorHelperFactory::factories();

	factories.push_back(factory);
}

/**
 * \brief Retrieve the list of all camera sensor helper factories
 * \return The list of camera sensor helper factories
 */
std::vector<CameraSensorHelperFactory *> &CameraSensorHelperFactory::factories()
{
	/*
	 * The static factories map is defined inside the function to ensure
	 * it gets initialized on first use, without any dependency on link
	 * order.
	 */
	static std::vector<CameraSensorHelperFactory *> factories;
	return factories;
}

/**
 * \fn CameraSensorHelperFactory::createInstance()
 * \brief Create an instance of the CameraSensorHelper corresponding to the
 * factory
 *
 * This virtual function is implemented by the REGISTER_CAMERA_SENSOR_HELPER()
 * macro. It creates a camera sensor helper instance associated with the camera
 * sensor model.
 *
 * \return A pointer to a newly constructed instance of the CameraSensorHelper
 * subclass corresponding to the factory
 */

/**
 * \var CameraSensorHelperFactory::name_
 * \brief The name of the factory
 */

/**
 * \def REGISTER_CAMERA_SENSOR_HELPER
 * \brief Register a camera sensor helper with the camera sensor helper factory
 * \param[in] name Sensor model name used to register the class
 * \param[in] helper Class name of CameraSensorHelper derived class to register
 *
 * Register a CameraSensorHelper subclass with the factory and make it available
 * to try and match sensors.
 */

/* -----------------------------------------------------------------------------
 * Sensor-specific subclasses
 */

#ifndef __DOXYGEN__

class CameraSensorHelperImx219 : public CameraSensorHelper
{
public:
	CameraSensorHelperImx219()
	{
		analogueGainConstants_ = { AnalogueGainLinear, 0, 256, -1, 256 };
	}
};
REGISTER_CAMERA_SENSOR_HELPER("imx219", CameraSensorHelperImx219)

class CameraSensorHelperImx258 : public CameraSensorHelper
{
public:
        CameraSensorHelperImx258()
        {
                analogueGainConstants_ = { AnalogueGainLinear, 0, 512, -1, 512 };
        }
};
REGISTER_CAMERA_SENSOR_HELPER("imx258", CameraSensorHelperImx258)

class CameraSensorHelperOv5670 : public CameraSensorHelper
{
public:
	CameraSensorHelperOv5670()
	{
		analogueGainConstants_ = { AnalogueGainLinear, 1, 0, 0, 128 };
	}
};
REGISTER_CAMERA_SENSOR_HELPER("ov5670", CameraSensorHelperOv5670)

class CameraSensorHelperOv5693 : public CameraSensorHelper
{
public:
	CameraSensorHelperOv5693()
	{
		analogueGainConstants_ = { AnalogueGainLinear, 1, 0, 0, 16 };
	}
};
REGISTER_CAMERA_SENSOR_HELPER("ov5693", CameraSensorHelperOv5693)

class CameraSensorHelperOv8865 : public CameraSensorHelper
{
public:
	CameraSensorHelperOv8865()
	{
		analogueGainConstants_ = { AnalogueGainLinear, 1, 0, 0, 128 };
	}
};
REGISTER_CAMERA_SENSOR_HELPER("ov8865", CameraSensorHelperOv8865)

class CameraSensorHelperOv13858 : public CameraSensorHelper
{
public:
	CameraSensorHelperOv13858()
	{
		analogueGainConstants_ = { AnalogueGainLinear, 1, 0, 0, 128 };
	}
};
REGISTER_CAMERA_SENSOR_HELPER("ov13858", CameraSensorHelperOv13858)

#endif /* __DOXYGEN__ */

} /* namespace ipa */

} /* namespace libcamera */