diff --git a/tests/color_util.c b/tests/color_util.c
index 66a23f3b..44d1e034 100644
--- a/tests/color_util.c
+++ b/tests/color_util.c
@@ -232,6 +232,29 @@ color_float_apply_curve(enum transfer_fn fn, struct color_float c)
 	return c;
 }
 
+/*
+ * Returns the result of the matrix-vector multiplication mat * c.
+ */
+struct color_float
+color_float_apply_matrix(const struct lcmsMAT3 *mat, struct color_float c)
+{
+	struct color_float result;
+	unsigned i, j;
+
+	/*
+	 * The matrix has an array of columns, hence i indexes to rows and
+	 * j indexes to columns.
+	 */
+	for (i = 0; i < 3; i++) {
+		result.rgb[i] = 0.0f;
+		for (j = 0; j < 3; j++)
+			result.rgb[i] += mat->v[j].n[i] * c.rgb[j];
+	}
+
+	result.a = c.a;
+	return result;
+}
+
 void
 process_pixel_using_pipeline(enum transfer_fn pre_curve,
 			     const struct lcmsMAT3 *mat,
@@ -239,18 +262,9 @@ process_pixel_using_pipeline(enum transfer_fn pre_curve,
 			     const struct color_float *in,
 			     struct color_float *out)
 {
-	int i, j;
 	struct color_float cf;
-	float tmp;
 
 	cf = color_float_apply_curve(pre_curve, *in);
-
-	for (i = 0; i < 3; i++) {
-		tmp = 0.0f;
-		for (j = 0; j < 3; j++)
-			tmp += cf.rgb[j] * mat->v[j].n[i];
-		out->rgb[i] = tmp;
-	}
-
-	*out = color_float_apply_curve(post_curve, *out);
+	cf = color_float_apply_matrix(mat, cf);
+	*out = color_float_apply_curve(post_curve, cf);
 }
diff --git a/tests/color_util.h b/tests/color_util.h
index 3e8e2abd..3fc21aa4 100644
--- a/tests/color_util.h
+++ b/tests/color_util.h
@@ -36,6 +36,7 @@ enum color_chan_index {
 	COLOR_CHAN_NUM
 };
 
+/* column vector when used in linear algebra */
 struct color_float {
 	union {
 		float rgb[COLOR_CHAN_NUM];
@@ -46,11 +47,13 @@ struct color_float {
 	float a;
 };
 
+/* column vector */
 struct lcmsVEC3 {
 	float n[3];
 };
 
 struct lcmsMAT3 {
+	/* array of columns */
 	struct lcmsVEC3 v[3];
 };
 
@@ -99,3 +102,6 @@ process_pixel_using_pipeline(enum transfer_fn pre_curve,
 			     enum transfer_fn post_curve,
 			     const struct color_float *in,
 			     struct color_float *out);
+
+struct color_float
+color_float_apply_matrix(const struct lcmsMAT3 *mat, struct color_float c);