Add mask expansion slider to enlarge safe area around detected person

data/locale/en-US.ini

@@ -36,3 +36,5 @@ FocalBlurGroup="Focal blur settings"
 ThresholdGroup="Threshold settings"
 EnableImageSimilarity="Skip image based on similarity?"
 ImageSimilarityThreshold="Sim. thresh. (high -> sensitive)"
+TemporalSmoothFactor="Temporal smooth factor"
+MaskExpansion="Mask expansion"

src/background-filter.cpp

@@ -38,6 +38,7 @@ struct background_removal_filter : public filter_data {
 	float contourFilter = 0.05f;
 	float smoothContour = 0.5f;
 	float feather = 0.0f;
+	int maskExpansion = 0;
 
 	cv::Mat backgroundMask;
 	cv::Mat lastBackgroundMask;
@@ -103,7 +104,7 @@ static bool enable_advanced_settings(obs_properties_t *ppts, obs_property_t *p,
 	for (const char *prop_name :
 	     {"model_select", "useGPU", "mask_every_x_frames", "numThreads", "enable_focal_blur", "enable_threshold",
 	      "threshold_group", "focal_blur_group", "temporal_smooth_factor", "image_similarity_threshold",
-	      "enable_image_similarity"}) {
+	      "enable_image_similarity", "mask_expansion"}) {
 		p = obs_properties_get(ppts, prop_name);
 		obs_property_set_visible(p, enabled);
 	}
@@ -148,6 +149,9 @@ obs_properties_t *background_filter_properties(void *data)
 	obs_properties_add_group(props, "threshold_group", obs_module_text("ThresholdGroup"), OBS_GROUP_NORMAL,
 				 threshold_props);
 
+	/* Mask expansion slider - in advanced settings */
+	obs_properties_add_int_slider(props, "mask_expansion", obs_module_text("MaskExpansion"), -30, 30, 1);
+
 	/* GPU, CPU and performance Props */
 	obs_property_t *p_use_gpu = obs_properties_add_list(props, "useGPU", obs_module_text("InferenceDevice"),
 							    OBS_COMBO_TYPE_LIST, OBS_COMBO_FORMAT_STRING);
@@ -227,6 +231,7 @@ void background_filter_defaults(obs_data_t *settings)
 	obs_data_set_default_double(settings, "threshold", 0.5);
 	obs_data_set_default_double(settings, "contour_filter", 0.05);
 	obs_data_set_default_double(settings, "smooth_contour", 0.5);
+	obs_data_set_default_double(settings, "mask_expansion", 0);
 	obs_data_set_default_double(settings, "feather", 0.0);
 #if defined(__APPLE__)
 	obs_data_set_default_string(settings, "useGPU", USEGPU_CPU);
@@ -258,6 +263,7 @@ void background_filter_update(void *data, obs_data_t *settings)
 
 	tf->contourFilter = (float)obs_data_get_double(settings, "contour_filter");
 	tf->smoothContour = (float)obs_data_get_double(settings, "smooth_contour");
+	tf->maskExpansion = (float)obs_data_get_double(settings, "mask_expansion");
 	tf->feather = (float)obs_data_get_double(settings, "feather");
 	tf->maskEveryXFrames = (int)obs_data_get_int(settings, "mask_every_x_frames");
 	tf->maskEveryXFramesCount = (int)(0);
@@ -340,6 +346,7 @@ void background_filter_update(void *data, obs_data_t *settings)
 	obs_log(LOG_INFO, "  Threshold: %f", tf->threshold);
 	obs_log(LOG_INFO, "  Contour Filter: %f", tf->contourFilter);
 	obs_log(LOG_INFO, "  Smooth Contour: %f", tf->smoothContour);
+	obs_log(LOG_INFO, "  Mask Expansion: %f", tf->maskExpansion);
 	obs_log(LOG_INFO, "  Feather: %f", tf->feather);
 	obs_log(LOG_INFO, "  Mask Every X Frames: %d", tf->maskEveryXFrames);
 	obs_log(LOG_INFO, "  Enable Image Similarity: %s", tf->enableImageSimilarity ? "true" : "false");
@@ -559,6 +566,15 @@ void background_filter_video_tick(void *data, float seconds)
 					backgroundMask = backgroundMask > 128;
 				}
 
+				// Expand or shrink the mask
+				if (tf->maskExpansion > 0.0) {
+					cv::erode(backgroundMask, backgroundMask, cv::Mat(), cv::Point(-1, -1),
+						  tf->maskExpansion);
+				} else if (tf->maskExpansion < 0.0) {
+					cv::dilate(backgroundMask, backgroundMask, cv::Mat(), cv::Point(-1, -1),
+						   -tf->maskExpansion);
+				}
+
 				if (tf->feather > 0.0) {
 					// Feather (blur) the mask
 					int k_size = (int)(40 * tf->feather);