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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2021, Google inc.
*
* tone_mapping.cpp - IPU3 ToneMapping and Gamma control
*/
#include "tone_mapping.h"
#include <cmath>
#include <string.h>
/**
* \file tone_mapping.h
*/
namespace libcamera {
namespace ipa::ipu3::algorithms {
/**
* \class ToneMapping
* \brief A class to handle tone mapping based on gamma
*
* This algorithm improves the image dynamic using a look-up table which is
* generated based on a gamma parameter.
*/
ToneMapping::ToneMapping()
: gamma_(1.0)
{
}
/**
* \brief Configure the tone mapping given a configInfo
* \param[in] context The shared IPA context
* \param[in] configInfo The IPA configuration data
*
* \return 0
*/
int ToneMapping::configure(IPAContext &context,
[[maybe_unused]] const IPAConfigInfo &configInfo)
{
/* Initialise tone mapping gamma value. */
context.activeState.toneMapping.gamma = 0.0;
return 0;
}
/**
* \brief Fill in the parameter structure, and enable gamma control
* \param context The shared IPA context
* \param params The IPU3 parameters
*
* Populate the IPU3 parameter structure with our tone mapping look up table and
* enable the gamma control module in the processing blocks.
*/
void ToneMapping::prepare([[maybe_unused]] IPAContext &context,
ipu3_uapi_params *params)
{
/* Copy the calculated LUT into the parameters buffer. */
memcpy(params->acc_param.gamma.gc_lut.lut,
context.activeState.toneMapping.gammaCorrection.lut,
IPU3_UAPI_GAMMA_CORR_LUT_ENTRIES *
sizeof(params->acc_param.gamma.gc_lut.lut[0]));
/* Enable the custom gamma table. */
params->use.acc_gamma = 1;
params->acc_param.gamma.gc_ctrl.enable = 1;
}
/**
* \brief Calculate the tone mapping look up table
* \param context The shared IPA context
* \param frameContext The current frame context
* \param stats The IPU3 statistics and ISP results
*
* The tone mapping look up table is generated as an inverse power curve from
* our gamma setting.
*/
void ToneMapping::process(IPAContext &context, [[maybe_unused]] IPAFrameContext *frameContext,
[[maybe_unused]] const ipu3_uapi_stats_3a *stats)
{
/*
* Hardcode gamma to 1.1 as a default for now.
*
* \todo Expose gamma control setting through the libcamera control API
*/
gamma_ = 1.1;
if (context.activeState.toneMapping.gamma == gamma_)
return;
struct ipu3_uapi_gamma_corr_lut &lut =
context.activeState.toneMapping.gammaCorrection;
for (uint32_t i = 0; i < std::size(lut.lut); i++) {
double j = static_cast<double>(i) / (std::size(lut.lut) - 1);
double gamma = std::pow(j, 1.0 / gamma_);
/* The output value is expressed on 13 bits. */
lut.lut[i] = gamma * 8191;
}
context.activeState.toneMapping.gamma = gamma_;
}
} /* namespace ipa::ipu3::algorithms */
} /* namespace libcamera */
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