libcamera: software_isp: lut: Make gamma from lut.cpp available in debayer params

Provide the gamma used in IPA to Bayer parameters. We will pass Gamma into
the shader via a uniform and can then tweak that value from outside at
will.

Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/software_isp/debayer_params.h

@@ -58,6 +58,7 @@ struct DebayerParams {
 	 */
 	Matrix<float, 3, 3> ccm;
 	RGB<float> blackLevel;
+	float gamma;
 };
 
 } /* namespace libcamera */

src/ipa/simple/algorithms/lut.cpp

@@ -147,6 +147,8 @@ void Lut::prepare(IPAContext &context,
 			params->gammaLut[i] = gammaTable[i / div];
 		}
 	}
+
+	params->gamma = context.configuration.gamma;
 }
 
 void Lut::process([[maybe_unused]] IPAContext &context,

src/libcamera/software_isp/debayer.cpp

@@ -110,6 +110,11 @@ namespace libcamera {
  * \brief Blacklevel gains for the GPUISP
  */
 
+/**
+ * \var DebayerParams::gamma
+ * \brief Gamma value for the GPUISP
+ */
+
 /**
  * \class Debayer
  * \brief Base debayering class