[gnome-color-manager/colord] huey: remove the dark current values before scaling for the calibration matrix

[Richard Hughes <rhughes src gnome org>]

commit 3a975bfd846d21712709f1b102a3d1aae5f4f101
Author: Richard Hughes <richard hughsie com>
Date:   Sun Feb 13 12:58:01 2011 +0000

    huey: remove the dark current values before scaling for the calibration matrix
    
    This is the only way that makes sense, otherwise the dark current values would
    depend on the calibration matrix values, which seems redundant.

 src/gcm-sensor-huey.c |  136 +++++++++++++++++++++++++++++++------------------
 1 files changed, 87 insertions(+), 49 deletions(-)
---
diff --git a/src/gcm-sensor-huey.c b/src/gcm-sensor-huey.c
index 3bdebdc..dc6e59b 100644
--- a/src/gcm-sensor-huey.c
+++ b/src/gcm-sensor-huey.c
@@ -1,6 +1,6 @@
 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
  *
- * Copyright (C) 2010 Richard Hughes <richard hughsie com>
+ * Copyright (C) 2010-2011 Richard Hughes <richard hughsie com>
  *
  * Licensed under the GNU Lesser General Public License Version 2.1
  *
@@ -89,7 +89,7 @@ G_DEFINE_TYPE (GcmSensorHuey, gcm_sensor_huey, GCM_TYPE_SENSOR)
 /* Picked out of thin air, just to try to match reality...
  * I have no idea why we need to do this, although it probably
  * indicates we doing something wrong. */
-#define HUEY_XYZ_POST_MULTIPLY_SCALE_FACTOR	2000
+#define HUEY_XYZ_POST_MULTIPLY_SCALE_FACTOR	3.5
 
 /**
  * gcm_sensor_huey_print_data:
@@ -610,13 +610,23 @@ typedef struct {
 	guint16	B;
 } GcmSensorHueyMultiplier;
 
+typedef struct {
+	guint32	R;
+	guint32	G;
+	guint32	B;
+} GcmSensorHueyDeviceRaw;
+
 /**
  * gcm_sensor_huey_sample_for_threshold:
  **/
 static gboolean
-gcm_sensor_huey_sample_for_threshold (GcmSensorHuey *sensor_huey, GcmSensorHueyMultiplier *threshold, GcmColorRGB *values, GError **error)
+gcm_sensor_huey_sample_for_threshold (GcmSensorHuey *sensor_huey,
+				      GcmSensorHueyMultiplier *threshold,
+				      GcmSensorHueyDeviceRaw *raw,
+				      GError **error)
 {
-	guchar request[] = { GCM_SENSOR_HUEY_COMMAND_SENSOR_MEASURE_RGB, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
+	guchar request[] = { GCM_SENSOR_HUEY_COMMAND_SENSOR_MEASURE_RGB,
+			     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
 	guchar reply[8];
 	gboolean ret;
 	gsize reply_read;
@@ -636,7 +646,7 @@ gcm_sensor_huey_sample_for_threshold (GcmSensorHuey *sensor_huey, GcmSensorHueyM
 		goto out;
 
 	/* get value */
-	values->R = (gdouble) threshold->R / (gdouble)gcm_buffer_read_uint32_be (reply+2);
+	raw->R = gcm_buffer_read_uint32_be (reply+2);
 
 	/* get green */
 	request[0] = GCM_SENSOR_HUEY_COMMAND_READ_GREEN;
@@ -649,7 +659,7 @@ gcm_sensor_huey_sample_for_threshold (GcmSensorHuey *sensor_huey, GcmSensorHueyM
 		goto out;
 
 	/* get value */
-	values->G = (gdouble) threshold->G / (gdouble)gcm_buffer_read_uint32_be (reply+2);
+	raw->G = gcm_buffer_read_uint32_be (reply+2);
 
 	/* get blue */
 	request[0] = GCM_SENSOR_HUEY_COMMAND_READ_BLUE;
@@ -662,7 +672,7 @@ gcm_sensor_huey_sample_for_threshold (GcmSensorHuey *sensor_huey, GcmSensorHueyM
 		goto out;
 
 	/* get value */
-	values->B = (gdouble) threshold->B / (gdouble)gcm_buffer_read_uint32_be (reply+2);
+	raw->B = gcm_buffer_read_uint32_be (reply+2);
 out:
 	return ret;
 }
@@ -670,53 +680,49 @@ out:
 /**
  * gcm_sensor_huey_convert_device_RGB_to_XYZ:
  *
- * / X \   (( / R \             )   / d \    / c a l \ )
- * | Y | = (( | G | x pre-scale ) - | r |  * | m a t | ) x post_scale
- * \ Z /   (( \ B /             )   \ k /    \ l c d / )
+ * / X \   ( / R \    / c a l \ )
+ * | Y | = ( | G |  * | m a t | ) x post_scale
+ * \ Z /   ( \ B /    \ l c d / )
  *
- * The device RGB values have to be scaled to something in the same
- * scale as the dark calibration. The results then have to be scaled
- * after convolving. I assume the first is a standard value, and the
- * second scale must be available in the eeprom somewhere.
+ * FIXME: I assume the post_scale is in the eeprom somewhere.
  **/
 static void
-gcm_sensor_huey_convert_device_RGB_to_XYZ (GcmColorRGB *src, GcmColorXYZ *dest,
-					   GcmMat3x3 *calibration, GcmVec3 *dark_offset,
-					   gdouble pre_scale, gdouble post_scale)
+gcm_sensor_huey_convert_device_RGB_to_XYZ (GcmColorRGB *src,
+					   GcmColorXYZ *dest,
+					   GcmMat3x3 *calibration,
+					   gdouble post_scale)
 {
-	GcmVec3 *color_native_vec3;
 	GcmVec3 *color_result_vec3;
-	GcmVec3 temp;
-
-	/* pre-multiply */
-	color_native_vec3 = gcm_color_get_RGB_Vec3 (src);
-	gcm_vec3_scalar_multiply (color_native_vec3, pre_scale, &temp);
-
-	/* remove dark calibration */
-	gcm_vec3_subtract (&temp, dark_offset, &temp);
+	GcmVec3 *temp;
 
 	/* convolve */
+	temp = gcm_color_get_RGB_Vec3 (src);
 	color_result_vec3 = gcm_color_get_XYZ_Vec3 (dest);
-	gcm_mat33_vector_multiply (calibration, &temp, color_result_vec3);
+	gcm_mat33_vector_multiply (calibration, temp, color_result_vec3);
 
 	/* post-multiply */
-	gcm_vec3_scalar_multiply (color_result_vec3, post_scale, color_result_vec3);
+	gcm_vec3_scalar_multiply (color_result_vec3,
+				  post_scale,
+				  color_result_vec3);
 }
 
 static void
-gcm_sensor_huey_sample_thread_cb (GSimpleAsyncResult *res, GObject *object, GCancellable *cancellable)
+gcm_sensor_huey_sample_thread_cb (GSimpleAsyncResult *res,
+				  GObject *object,
+				  GCancellable *cancellable)
 {
-	GcmSensor *sensor = GCM_SENSOR (object);
-	GError *error = NULL;
 	gboolean ret = FALSE;
-	gdouble precision_value;
-	GcmColorRGB color_native;
+	GcmColorRGB values;
 	GcmColorXYZ color_result;
 	GcmColorXYZ *tmp;
-	GcmSensorHueyMultiplier multiplier;
-	GcmSensorHuey *sensor_huey = GCM_SENSOR_HUEY (sensor);
 	GcmMat3x3 *device_calibration;
+	GcmSensorHueyDeviceRaw color_native;
+	GcmSensorHueyMultiplier multiplier;
 	GcmSensorOutputType output_type;
+	GcmVec3 *temp;
+	GError *error = NULL;
+	GcmSensor *sensor = GCM_SENSOR (object);
+	GcmSensorHuey *sensor_huey = GCM_SENSOR_HUEY (sensor);
 
 	/* ensure sensor is started */
 	if (!sensor_huey->priv->done_startup) {
@@ -746,19 +752,22 @@ gcm_sensor_huey_sample_thread_cb (GSimpleAsyncResult *res, GObject *object, GCan
 	multiplier.R = 1;
 	multiplier.G = 1;
 	multiplier.B = 1;
-	ret = gcm_sensor_huey_sample_for_threshold (sensor_huey, &multiplier, &color_native, &error);
+	ret = gcm_sensor_huey_sample_for_threshold (sensor_huey,
+						    &multiplier,
+						    &color_native,
+						    &error);
 	if (!ret) {
 		g_simple_async_result_set_from_error (res, error);
 		g_error_free (error);
 		goto out;
 	}
-	g_debug ("initial values: red=%0.6lf, green=%0.6lf, blue=%0.6lf", color_native.R, color_native.G, color_native.B);
+	g_debug ("initial values: red=%i, green=%i, blue=%i",
+		 color_native.R, color_native.G, color_native.B);
 
-	/* compromise between the amount of time and the precision */
-	precision_value = (gdouble) HUEY_POLL_FREQUENCY;
-	multiplier.R = precision_value * color_native.R;
-	multiplier.G = precision_value * color_native.G;
-	multiplier.B = precision_value * color_native.B;
+	/* try to fill the 16 bit register for accuracy */
+	multiplier.R = HUEY_POLL_FREQUENCY / color_native.R;
+	multiplier.G = HUEY_POLL_FREQUENCY / color_native.G;
+	multiplier.B = HUEY_POLL_FREQUENCY / color_native.B;
 
 	/* don't allow a value of zero */
 	if (multiplier.R == 0)
@@ -767,15 +776,45 @@ gcm_sensor_huey_sample_thread_cb (GSimpleAsyncResult *res, GObject *object, GCan
 		multiplier.G = 1;
 	if (multiplier.B == 0)
 		multiplier.B = 1;
-	g_debug ("using multiplier factor: red=%i, green=%i, blue=%i", multiplier.R, multiplier.G, multiplier.B);
-	ret = gcm_sensor_huey_sample_for_threshold (sensor_huey, &multiplier, &color_native, &error);
+	g_debug ("using multiplier factor: red=%i, green=%i, blue=%i",
+		 multiplier.R, multiplier.G, multiplier.B);
+	ret = gcm_sensor_huey_sample_for_threshold (sensor_huey,
+						    &multiplier,
+						    &color_native,
+						    &error);
 	if (!ret) {
 		g_simple_async_result_set_from_error (res, error);
 		g_error_free (error);
 		goto out;
 	}
 
-	g_debug ("scaled values: red=%0.6lf, green=%0.6lf, blue=%0.6lf", color_native.R, color_native.G, color_native.B);
+	g_debug ("raw values: red=%i, green=%i, blue=%i",
+		 color_native.R, color_native.G, color_native.B);
+
+	/* get DeviceRGB values */
+	values.R = (gdouble) multiplier.R * 0.5f * HUEY_POLL_FREQUENCY / ((gdouble) color_native.R);
+	values.G = (gdouble) multiplier.G * 0.5f * HUEY_POLL_FREQUENCY / ((gdouble) color_native.G);
+	values.B = (gdouble) multiplier.B * 0.5f * HUEY_POLL_FREQUENCY / ((gdouble) color_native.B);
+
+	g_debug ("scaled values: red=%0.6lf, green=%0.6lf, blue=%0.6lf",
+		 values.R, values.G, values.B);
+
+	/* remove dark offset */
+	temp = gcm_color_get_RGB_Vec3 (&values);
+	gcm_vec3_subtract (temp,
+			   &sensor_huey->priv->dark_offset,
+			   temp);
+
+	g_debug ("dark offset values: red=%0.6lf, green=%0.6lf, blue=%0.6lf",
+		 values.R, values.G, values.B);
+
+	/* negative values don't make sense (device needs recalibration) */
+	if (values.R < 0.0f)
+		values.R = 0.0f;
+	if (values.G < 0.0f)
+		values.G = 0.0f;
+	if (values.B < 0.0f)
+		values.B = 0.0f;
 
 	/* we use different calibration matrices for each output type */
 	if (output_type == GCM_SENSOR_OUTPUT_TYPE_LCD) {
@@ -787,14 +826,13 @@ gcm_sensor_huey_sample_thread_cb (GSimpleAsyncResult *res, GObject *object, GCan
 	}
 
 	/* convert from device RGB to XYZ */
-	gcm_sensor_huey_convert_device_RGB_to_XYZ (&color_native,
+	gcm_sensor_huey_convert_device_RGB_to_XYZ (&values,
 						   &color_result,
 						   device_calibration,
-						   &sensor_huey->priv->dark_offset,
-						   2000.0f,
 						   HUEY_XYZ_POST_MULTIPLY_SCALE_FACTOR);
 
-	g_debug ("finished values: red=%0.6lf, green=%0.6lf, blue=%0.6lf", color_result.X, color_result.Y, color_result.Z);
+	g_debug ("finished values: red=%0.6lf, green=%0.6lf, blue=%0.6lf",
+		 color_result.X, color_result.Y, color_result.Z);
 
 	/* save result */
 	tmp = g_new0 (GcmColorXYZ, 1);