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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Copyright (C) 2019, Raspberry Pi (Trading) Limited
*
* contrast.cpp - contrast (gamma) control algorithm
*/
#include <stdint.h>
#include <libcamera/base/log.h>
#include "../contrast_status.h"
#include "../histogram.hpp"
#include "contrast.hpp"
using namespace RPiController;
using namespace libcamera;
LOG_DEFINE_CATEGORY(RPiContrast)
// This is a very simple control algorithm which simply retrieves the results of
// AGC and AWB via their "status" metadata, and applies digital gain to the
// colour channels in accordance with those instructions. We take care never to
// apply less than unity gains, as that would cause fully saturated pixels to go
// off-white.
#define NAME "rpi.contrast"
Contrast::Contrast(Controller *controller)
: ContrastAlgorithm(controller), brightness_(0.0), contrast_(1.0)
{
}
char const *Contrast::Name() const
{
return NAME;
}
void Contrast::Read(boost::property_tree::ptree const ¶ms)
{
// enable adaptive enhancement by default
config_.ce_enable = params.get<int>("ce_enable", 1);
// the point near the bottom of the histogram to move
config_.lo_histogram = params.get<double>("lo_histogram", 0.01);
// where in the range to try and move it to
config_.lo_level = params.get<double>("lo_level", 0.015);
// but don't move by more than this
config_.lo_max = params.get<double>("lo_max", 500);
// equivalent values for the top of the histogram...
config_.hi_histogram = params.get<double>("hi_histogram", 0.95);
config_.hi_level = params.get<double>("hi_level", 0.95);
config_.hi_max = params.get<double>("hi_max", 2000);
config_.gamma_curve.Read(params.get_child("gamma_curve"));
}
void Contrast::SetBrightness(double brightness)
{
brightness_ = brightness;
}
void Contrast::SetContrast(double contrast)
{
contrast_ = contrast;
}
static void fill_in_status(ContrastStatus &status, double brightness,
double contrast, Pwl &gamma_curve)
{
status.brightness = brightness;
status.contrast = contrast;
for (int i = 0; i < CONTRAST_NUM_POINTS - 1; i++) {
int x = i < 16 ? i * 1024
: (i < 24 ? (i - 16) * 2048 + 16384
: (i - 24) * 4096 + 32768);
status.points[i].x = x;
status.points[i].y = std::min(65535.0, gamma_curve.Eval(x));
}
status.points[CONTRAST_NUM_POINTS - 1].x = 65535;
status.points[CONTRAST_NUM_POINTS - 1].y = 65535;
}
void Contrast::Initialise()
{
// Fill in some default values as Prepare will run before Process gets
// called.
fill_in_status(status_, brightness_, contrast_, config_.gamma_curve);
}
void Contrast::Prepare(Metadata *image_metadata)
{
std::unique_lock<std::mutex> lock(mutex_);
image_metadata->Set("contrast.status", status_);
}
Pwl compute_stretch_curve(Histogram const &histogram,
ContrastConfig const &config)
{
Pwl enhance;
enhance.Append(0, 0);
// If the start of the histogram is rather empty, try to pull it down a
// bit.
double hist_lo = histogram.Quantile(config.lo_histogram) *
(65536 / NUM_HISTOGRAM_BINS);
double level_lo = config.lo_level * 65536;
LOG(RPiContrast, Debug)
<< "Move histogram point " << hist_lo << " to " << level_lo;
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