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ipa: rpi:: denoise: Implement TDN back-off for CDN deviation

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The CDN (colour denoise) deviation gets gradually reduced frame by
frame as TDN (temporal denoise) comes in and has more effect. CDN is
more harmful to image detail than TDN, so ramping it down in favour of
TDN is beneficial.

The tuning file parameters are chosen so that existing tuning files
don't have to be updated and will carry on working "mostly like they
did" (apart from the new back-off).

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
David Plowman
2025-08-15 08:24:26 +01:00
committed by Kieran Bingham
parent db288a6ce4
commit 524fb97084
2 changed files with 23 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
src/ipa/rpi/controller/rpi/denoise.cpp
View File

@@ -37,7 +37,18 @@ int DenoiseConfig::read(const libcamera::YamlObject &params)
cdnEnable = params.contains("cdn");
if (cdnEnable) {
auto &cdnParams = params["cdn"];
cdnDeviation = cdnParams["deviation"].get<double>(120);
/*
* For backwards compatibility with existing tuning files, interpret "deviation"
* as giving the "no TDN" deviation, where present. But "deviation_no_tdn" takes
* precedence when that's available.
*/
cdnDeviationNoTdn = cdnParams["deviation"].get<double>(150);
cdnDeviationNoTdn = cdnParams["deviation_no_tdn"].get<double>(cdnDeviationNoTdn);
/*
* A third the value of the no TDN deviation is about right for with-TDN, if
* the user hasn't specified otherwise.
*/
cdnDeviationWithTdn = cdnParams["deviation_with_tdn"].get<double>(cdnDeviationNoTdn / 3);
cdnStrength = cdnParams["strength"].get<double>(0.2);
}
@@ -48,13 +59,14 @@ int DenoiseConfig::read(const libcamera::YamlObject &params)
tdnThreshold = tdnParams["threshold"].get<double>(0.75);
} else if (sdnEnable) {
/*
* If SDN is enabled but TDN isn't, overwrite all the SDN settings
* If SDN is enabled but TDN isn't, overwrite all the SDN/CDN settings
* with the "no TDN" versions. This makes it easier to enable or
* disable TDN in the tuning file without editing all the other
* parameters.
*/
sdnDeviation = sdnDeviation2 = sdnDeviationNoTdn;
sdnStrength = sdnStrengthNoTdn;
cdnDeviationWithTdn = cdnDeviationNoTdn;
}
return 0;
@@ -107,6 +119,7 @@ void Denoise::switchMode([[maybe_unused]] CameraMode const &cameraMode,
currentSdnDeviation_ = currentConfig_->sdnDeviationNoTdn;
currentSdnStrength_ = currentConfig_->sdnStrengthNoTdn;
currentSdnDeviation2_ = currentConfig_->sdnDeviationNoTdn;
currentCdnDeviation_ = currentConfig_->cdnDeviationNoTdn;
}
void Denoise::prepare(Metadata *imageMetadata)
@@ -159,8 +172,12 @@ void Denoise::prepare(Metadata *imageMetadata)
if (currentConfig_->cdnEnable && mode_ != DenoiseMode::ColourOff) {
struct CdnStatus cdn;
cdn.threshold = currentConfig_->cdnDeviation * noiseStatus.noiseSlope + noiseStatus.noiseConstant;
cdn.threshold = currentCdnDeviation_ * noiseStatus.noiseSlope + noiseStatus.noiseConstant;
cdn.strength = currentConfig_->cdnStrength;
/* For the next frame, we back off the CDN deviation as TDN ramps up. */
double f = currentConfig_->sdnTdnBackoff;
currentCdnDeviation_ = f * currentCdnDeviation_ + (1 - f) * currentConfig_->cdnDeviationWithTdn;
imageMetadata->set("cdn.status", cdn);
LOG(RPiDenoise, Debug)
<< "programmed cdn threshold " << cdn.threshold

4
src/ipa/rpi/controller/rpi/denoise.h
View File

@@ -23,7 +23,8 @@ struct DenoiseConfig {
double sdnDeviationNoTdn;
double sdnStrengthNoTdn;
double sdnTdnBackoff;
double cdnDeviation;
double cdnDeviationNoTdn;
double cdnDeviationWithTdn;
double cdnStrength;
double tdnDeviation;
double tdnThreshold;
@@ -54,6 +55,7 @@ private:
double currentSdnDeviation_;
double currentSdnStrength_;
double currentSdnDeviation2_;
double currentCdnDeviation_;
};
} // namespace RPiController