new file mode 100644
@@ -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 */
new file mode 100644
@@ -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 */
@@ -32,15 +32,26 @@ int Gamma::init(IPAContext &context,
void Gamma::updateGammaTable(IPAContext &context)
{
auto &gammaTable = context.activeState.gamma.gammaTable;
- auto blackLevel = context.activeState.black.level;
+ const auto blackLevel = context.activeState.black.level;
const unsigned int blackIndex =
blackLevel * IPAActiveState::kGammaLookupSize;
+ const auto contrast = context.activeState.knobs.contrast.value_or(1.0);
+
std::fill(gammaTable.begin(), gammaTable.begin() + blackIndex, 0);
const float divisor = kGammaLookupSize - blackIndex - 1.0;
- for (unsigned int i = blackIndex; i < kGammaLookupSize; i++)
- gammaTable[i] = UINT8_MAX * powf((i - blackIndex) / divisor,
- context.configuration.gamma);
+ for (unsigned int i = blackIndex; i < kGammaLookupSize; 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 Gamma::prepare(IPAContext &context,
@@ -53,7 +64,8 @@ void Gamma::prepare(IPAContext &context,
* since the black level gets updated only if a lower value is observed,
* it's not permanently prone to minor fluctuations or rounding errors.
*/
- if (context.activeState.gamma.blackLevel != context.activeState.black.level)
+ if (context.activeState.gamma.blackLevel != context.activeState.black.level ||
+ context.activeState.gamma.contrast != context.activeState.knobs.contrast)
updateGammaTable(context);
}
@@ -4,6 +4,7 @@ soft_simple_ipa_algorithms = files([
'awb.cpp',
'agc.cpp',
'blc.cpp',
+ 'contrast.cpp',
'gamma.cpp',
'lut.cpp',
])
@@ -46,7 +46,11 @@ struct IPAActiveState {
struct {
std::array<double, kGammaLookupSize> gammaTable;
double blackLevel;
+ double contrast;
} gamma;
+ struct {
+ std::optional<double> contrast; // 0..inf, 1 = neutral
+ } knobs;
};
struct IPAFrameContext : public FrameContext {
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@redhat.com> --- src/ipa/simple/algorithms/contrast.cpp | 45 ++++++++++++++++++++++++++ src/ipa/simple/algorithms/contrast.h | 37 +++++++++++++++++++++ src/ipa/simple/algorithms/gamma.cpp | 22 ++++++++++--- src/ipa/simple/algorithms/meson.build | 1 + src/ipa/simple/ipa_context.h | 4 +++ 5 files changed, 104 insertions(+), 5 deletions(-) create mode 100644 src/ipa/simple/algorithms/contrast.cpp create mode 100644 src/ipa/simple/algorithms/contrast.h