ipa: rpi: Add HDR support

Add support for the following HDR modes in the Raspberry Pi IPA:
- Night mode
- Single exposure mode
- Multi-exposure (merged and unmerged)

The algorithm is updated to expect the HDR short channel to meter
explicitly for highlights. This means that it will not in general
under-expose the short channel more than is actually necessary.

When images don't have much saturation, it's good to detect this so
that some of the boost we want to apply to the dark areas can be
implemented as regular gain. This means we can then adjust the tone
curve less, leading to less flat looking images.

The impact on the HDR algorithm is then that this determines how we
build tonemaps dynamically. The highlights are more-or-less correct
now, so we have to build a power-type curve that gives us the
appropriately configured targets in the lower part of the histogram.

We allow the tuning file to supply the maximum spatial gain value,
rather than the whole curve (though it can supply this if it
wants). Some parameter defaults are tweaked to be generally better
across the range of our cameras.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/ipa/rpi/controller/rpi/hdr.h b/src/ipa/rpi/controller/rpi/hdr.h
index 44272cb8..9b7327f8 100644
--- a/src/ipa/rpi/controller/rpi/hdr.h
+++ b/src/ipa/rpi/controller/rpi/hdr.h
@@ -26,7 +26,7 @@ struct HdrConfig {
 	std::map<unsigned int, std::string> channelMap;
 
 	/* Lens shading related parameters. */
-	Pwl spatialGain; /* Brightness to gain curve for different image regions. */
+	Pwl spatialGainCurve; /* Brightness to gain curve for different image regions. */
 	unsigned int diffusion; /* How much to diffuse the gain spatially. */
 
 	/* Tonemap related parameters. */
@@ -36,6 +36,14 @@ struct HdrConfig {
 	double iirStrength;
 	double strength;
 	Pwl tonemap;
+	/* These relate to adaptive tonemap calculation. */
+	double speed;
+	std::vector<double> hiQuantileTargets; /* quantiles to check for unsaturated images */
+	double hiQuantileMaxGain; /* the max gain we'll apply when unsaturated */
+	std::vector<double> quantileTargets; /* target values for histogram quantiles */
+	double powerMin; /* minimum tonemap power */
+	double powerMax; /* maximum tonemap power */
+	std::vector<double> contrastAdjustments; /* any contrast adjustment factors */
 
 	/* Stitch related parameters. */
 	bool stitchEnable;