[PATCH v2 1/2] libcamera: software_isp: Add contrast algorithm
Milan Zamazal
mzamazal at redhat.com
Wed Oct 9 21:33:16 CEST 2024
Software ISP is currently fully automatic and doesn't allow image
modifications by explicitly set control values. The user has no means
to make the image looking better.
This patch introduces contrast control algorithm, which can improve
e.g. a flat looking image. Based on the provided contrast value with a
range 0..infinity and 1.0 being the normal value, it applies a simple
S-curve modification to the image. The contrast algorithm just handles
the provided values, while the S-curve is applied in the gamma algorithm
on the computed gamma curve whenever the contrast value changes. Since
the algorithm is applied only on the lookup table already present, its
overhead is negligible.
This is a preparation patch without actually activating the contrast
algorithm, which will be done in the following patch.
Signed-off-by: Milan Zamazal <mzamazal at redhat.com>
---
src/ipa/simple/algorithms/contrast.cpp | 45 ++++++++++++++++++++++++++
src/ipa/simple/algorithms/contrast.h | 37 +++++++++++++++++++++
src/ipa/simple/algorithms/lut.cpp | 20 +++++++++---
src/ipa/simple/algorithms/meson.build | 1 +
src/ipa/simple/ipa_context.h | 7 ++++
5 files changed, 105 insertions(+), 5 deletions(-)
create mode 100644 src/ipa/simple/algorithms/contrast.cpp
create mode 100644 src/ipa/simple/algorithms/contrast.h
diff --git a/src/ipa/simple/algorithms/contrast.cpp b/src/ipa/simple/algorithms/contrast.cpp
new file mode 100644
index 000000000..1a2c14cf9
--- /dev/null
+++ b/src/ipa/simple/algorithms/contrast.cpp
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Red Hat Inc.
+ *
+ * Contrast adjustment
+ */
+
+#include "contrast.h"
+
+#include <optional>
+
+#include <libcamera/base/log.h>
+
+#include "control_ids.h"
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(IPASoftContrast)
+
+namespace ipa::soft::algorithms {
+
+int Contrast::configure(typename Module::Context &context,
+ [[maybe_unused]] const typename Module::Config &configInfo)
+{
+ context.activeState.knobs.contrast = std::optional<double>();
+ return 0;
+}
+
+void Contrast::queueRequest(typename Module::Context &context,
+ [[maybe_unused]] const uint32_t frame,
+ [[maybe_unused]] typename Module::FrameContext &frameContext,
+ const ControlList &controls)
+{
+ const auto &contrast = controls.get(controls::Contrast);
+ if (contrast.has_value()) {
+ context.activeState.knobs.contrast = contrast;
+ LOG(IPASoftContrast, Debug) << "Setting contrast to " << contrast.value();
+ }
+}
+
+REGISTER_IPA_ALGORITHM(Contrast, "Contrast")
+
+} /* namespace ipa::soft::algorithms */
+
+} /* namespace libcamera */
diff --git a/src/ipa/simple/algorithms/contrast.h b/src/ipa/simple/algorithms/contrast.h
new file mode 100644
index 000000000..0b3933099
--- /dev/null
+++ b/src/ipa/simple/algorithms/contrast.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Red Hat Inc.
+ *
+ * Contrast adjustment
+ */
+
+#pragma once
+
+#include <libcamera/controls.h>
+
+#include "algorithm.h"
+
+namespace libcamera {
+
+namespace ipa::soft::algorithms {
+
+class Contrast : public Algorithm
+{
+public:
+ Contrast() = default;
+ ~Contrast() = default;
+
+ int configure(typename Module::Context &context,
+ const typename Module::Config &configInfo)
+ override;
+
+ void queueRequest(typename Module::Context &context,
+ const uint32_t frame,
+ typename Module::FrameContext &frameContext,
+ const ControlList &controls)
+ override;
+};
+
+} /* namespace ipa::soft::algorithms */
+
+} /* namespace libcamera */
diff --git a/src/ipa/simple/algorithms/lut.cpp b/src/ipa/simple/algorithms/lut.cpp
index 9744e773a..8ebc824ce 100644
--- a/src/ipa/simple/algorithms/lut.cpp
+++ b/src/ipa/simple/algorithms/lut.cpp
@@ -32,16 +32,25 @@ int Lut::configure(IPAContext &context,
void Lut::updateGammaTable(IPAContext &context)
{
auto &gammaTable = context.activeState.gamma.gammaTable;
- auto blackLevel = context.activeState.blc.level;
+ const auto blackLevel = context.activeState.blc.level;
const unsigned int blackIndex = blackLevel * gammaTable.size() / 256;
+ const auto contrast = context.activeState.knobs.contrast.value_or(1.0);
std::fill(gammaTable.begin(), gammaTable.begin() + blackIndex, 0);
const float divisor = gammaTable.size() - blackIndex - 1.0;
- for (unsigned int i = blackIndex; i < gammaTable.size(); i++)
- gammaTable[i] = UINT8_MAX * std::pow((i - blackIndex) / divisor,
- context.configuration.gamma);
+ for (unsigned int i = blackIndex; i < gammaTable.size(); i++) {
+ double normalized = (i - blackIndex) / divisor;
+ /* Apply simple S-curve */
+ if (normalized < 0.5)
+ normalized = 0.5 * std::pow(normalized / 0.5, contrast);
+ else
+ normalized = 1.0 - 0.5 * std::pow((1.0 - normalized) / 0.5, contrast);
+ gammaTable[i] = UINT8_MAX *
+ std::pow(normalized, context.configuration.gamma);
+ }
context.activeState.gamma.blackLevel = blackLevel;
+ context.activeState.gamma.contrast = contrast;
}
void Lut::prepare(IPAContext &context,
@@ -55,7 +64,8 @@ void Lut::prepare(IPAContext &context,
* observed, it's not permanently prone to minor fluctuations or
* rounding errors.
*/
- if (context.activeState.gamma.blackLevel != context.activeState.blc.level)
+ if (context.activeState.gamma.blackLevel != context.activeState.blc.level ||
+ context.activeState.gamma.contrast != context.activeState.knobs.contrast)
updateGammaTable(context);
auto &gains = context.activeState.gains;
diff --git a/src/ipa/simple/algorithms/meson.build b/src/ipa/simple/algorithms/meson.build
index 37a2eb534..d75a7b2a1 100644
--- a/src/ipa/simple/algorithms/meson.build
+++ b/src/ipa/simple/algorithms/meson.build
@@ -4,5 +4,6 @@ soft_simple_ipa_algorithms = files([
'awb.cpp',
'agc.cpp',
'blc.cpp',
+ 'contrast.cpp',
'lut.cpp',
])
diff --git a/src/ipa/simple/ipa_context.h b/src/ipa/simple/ipa_context.h
index 3519f20f6..5118d6abf 100644
--- a/src/ipa/simple/ipa_context.h
+++ b/src/ipa/simple/ipa_context.h
@@ -8,8 +8,11 @@
#pragma once
#include <array>
+#include <optional>
#include <stdint.h>
+#include <libcamera/controls.h>
+
#include <libipa/fc_queue.h>
namespace libcamera {
@@ -44,7 +47,11 @@ struct IPAActiveState {
struct {
std::array<double, kGammaLookupSize> gammaTable;
uint8_t blackLevel;
+ double contrast;
} gamma;
+ struct {
+ std::optional<double> contrast; // 0..inf, 1 = neutral
+ } knobs;
};
struct IPAFrameContext : public FrameContext {
--
2.44.1
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