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libcamera: ipa: raspberrypi: Add sharpness strength control

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The sharpness control is, loosely speaking, a gain applied to
the amount of sharpening added to an image. We also report the
sharpness setting used back to the caller in metadata.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
This commit is contained in:
David Plowman 2020-06-23 10:14:03 +01:00 • committed by Laurent Pinchart
parent 58e63a6e7e
commit 0dbc6a507c
4 changed files with 50 additions and 7 deletions
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28
src/ipa/raspberrypi/controller/rpi/sharpen.cpp
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@ -17,7 +17,7 @@ using namespace RPi;
#define NAME "rpi.sharpen"
Sharpen::Sharpen(Controller *controller)
: Algorithm(controller)
: SharpenAlgorithm(controller), user_strength_(1.0)
{
}
@ -42,14 +42,32 @@ void Sharpen::Read(boost::property_tree::ptree const &params)
limit_ = params.get<double>("limit", 1.0);
}
void Sharpen::SetStrength(double strength)
{
// Note that this method is how an application sets the overall
// sharpening "strength". We call this the "user strength" field
// as there already is a strength_ field - being an internal gain
// parameter that gets passed to the ISP control code. Negative
// values are not allowed - coerce them to zero (no sharpening).
user_strength_ = std::max(0.0, strength);
}
void Sharpen::Prepare(Metadata *image_metadata)
{
// The user_strength_ affects the algorithm's internal gain directly, but
// we adjust the limit and threshold less aggressively. Using a sqrt
// function is an arbitrary but gentle way of accomplishing this.
double user_strength_sqrt = sqrt(user_strength_);
struct SharpenStatus status;
// Binned modes seem to need the sharpening toned down with this
// pipeline.
status.threshold = threshold_ * mode_factor_;
status.strength = strength_ / mode_factor_;
status.limit = limit_ / mode_factor_;
// pipeline, thus we use the mode_factor here. Also avoid
// divide-by-zero with the user_strength_sqrt.
status.threshold = threshold_ * mode_factor_ /
std::max(0.01, user_strength_sqrt);
status.strength = strength_ / mode_factor_ * user_strength_;
status.limit = limit_ / mode_factor_ * user_strength_sqrt;
// Finally, report any application-supplied parameters that were used.
status.user_strength = user_strength_;
image_metadata->Set("sharpen.status", status);
}