flatfielding factor instead of absolute & relative

ctapipe/calib/camera/calibrator.py

@@ -271,7 +271,7 @@ def _calibrate_dl1(self, event, tel_id):
                 dl1.peak_time -= remaining_shift
 
         # Calibrate extracted charge
-        dl1.image *= dl1_calib.relative_factor / dl1_calib.absolute_factor
+        dl1.image *= dl1_calib.flatfielding_factor
 
         # handle invalid pixels
         if self.invalid_pixel_handler is not None:

ctapipe/calib/camera/tests/test_calibrator.py

@@ -173,6 +173,9 @@ def test_dl1_charge_calib(example_subarray):
     relative = random.normal(1, 0.01, n_pixels)
     y /= relative[:, np.newaxis]
 
+    # Define flatfielding coefficients
+    flatfielding = relative / absolute
+
     # Define pedestal
     pedestal = random.uniform(-4, 4, n_pixels)
     y += pedestal[:, np.newaxis]
@@ -191,8 +194,7 @@ def test_dl1_charge_calib(example_subarray):
     np.testing.assert_allclose(event.dl1.tel[tel_id].image, y.sum(1), rtol=1e-4)
 
     event.calibration.tel[tel_id].dl1.pedestal_offset = pedestal
-    event.calibration.tel[tel_id].dl1.absolute_factor = absolute
-    event.calibration.tel[tel_id].dl1.relative_factor = relative
+    event.calibration.tel[tel_id].dl1.flatfielding_factor = flatfielding
 
     # Test without timing corrections
     calibrator(event)

ctapipe/containers.py

@@ -523,16 +523,11 @@ class DL1CameraCalibrationContainer(Container):
         " This value is subtracted from the waveforms of each pixel before"
         " the pulse extraction.",
     )
-    absolute_factor = Field(
+    flatfielding_factor = Field(
         1,
-        "Multiplicative coefficients for the absolute calibration of extracted charge into "
-        "physical units (e.g. photoelectrons or photons) for each pixel",
-    )
-    relative_factor = Field(
-        1,
-        "Multiplicative Coefficients for the relative correction between pixels to achieve a "
-        "uniform charge response (post absolute calibration) from a "
-        "uniform illumination.",
+        "Multiplicative coefficients for the relative correction between "
+        "pixels to achieve a uniform charge response "
+        "(post absolute calibration) from a uniform illumination.",
     )
     time_shift = Field(
         None,

docs/changes/2433.bugfix.rst

@@ -0,0 +1,3 @@
+Change DL1 charge calibration in event to be a single, relative coefficient
+per channel / pixel instead of having an absolute factor for conversion to
+p.e. and a relative factor for achieving a uniform charge distrubtion.