Index: conf.c
===================================================================
--- conf.c	(revision 213)
+++ conf.c	(working copy)
@@ -134,6 +134,7 @@
 	text_double:           0,
 	despeckle:             NULL,
 	minimum_motion_frames: 1,
+	referense_image_age:   1,
 	pid_file:              NULL,
 	// debug_parameter:       0
 };
@@ -438,6 +439,15 @@
 	print_int
 	},
 	{
+	"referense_image_age",
+	"# When picking referense image, how old should it be in frames.\n"
+	"# Valid range: 1 to hundreds\n"
+	"# Default is 1, previous frame\n",
+	CONF_OFFSET(referense_image_age),
+	copy_int,
+	print_int
+	},
+	{
 	"minimum_motion_frames",
 	"# Picture frames must contain motion at least the specified number of frames\n"
 	"# in a row before they are detected as true motion. At the default of 1, all\n"
Index: conf.h
===================================================================
--- conf.h	(revision 213)
+++ conf.h	(working copy)
@@ -117,6 +117,10 @@
 	const char *text_event;
 	int text_double;
 	const char *despeckle;
+	
+	/* Frame cont before a frame becomes the referense image */
+	int referense_image_age;
+	
 	int minimum_motion_frames;
 	char *pid_file;
 	// int debug_parameter;
Index: motion.c
===================================================================
--- motion.c	(revision 213)
+++ motion.c	(working copy)
@@ -523,7 +523,9 @@
 	memset(cnt->imgs.image_ring_buffer, 0x80, cnt->imgs.size);  /* initialize to grey */
 	cnt->imgs.ref = mymalloc(cnt->imgs.size);
 	cnt->imgs.out = mymalloc(cnt->imgs.size);
-	cnt->imgs.image_virgin = mymalloc(cnt->imgs.size);
+	cnt->imgs.image_virgin_ring_buffer = mymalloc(cnt->imgs.size); /* Allocate buffer for 1 frame */
+	cnt->imgs.image_virgin_ring_size = 1;
+	cnt->imgs.image_virgin = cnt->imgs.image_virgin_ring_buffer;
 	memset(cnt->imgs.image_virgin, 0x80, cnt->imgs.size);       /* initialize to grey */
 	cnt->imgs.smartmask = mymalloc(cnt->imgs.motionsize);
 	cnt->imgs.smartmask_final = mymalloc(cnt->imgs.motionsize);
@@ -833,6 +835,34 @@
 			}
 		}
 
+		/* Check if our virgin buffer is still the right size
+		 */
+		{
+			int new_virgin_size = cnt->conf.referense_image_age;
+
+			if (cnt->imgs.image_virgin_ring_size != new_virgin_size) {
+				/* Only resize if :
+				 * decreasing at last position in new buffer
+				 * increasing at last position in old buffer 
+				 * e.g. at end of smallest buffer */
+				int smallest;
+				if (new_virgin_size < cnt->conf.referense_image_age) { /* Decreasing */
+					smallest = new_virgin_size;
+				} else { /* Increasing */
+					smallest = cnt->imgs.image_virgin_ring_size;
+				}
+				if (cnt->imgs.image_virgin_ring_last_in == smallest - 1) {
+					void *tmp;
+					tmp = mymalloc(cnt->imgs.size * new_virgin_size);
+					/* Copy old content into new buffer */
+					memcpy(tmp, cnt->imgs.image_virgin_ring_buffer, cnt->imgs.size * smallest);
+					free(cnt->imgs.image_virgin_ring_buffer);
+					cnt->imgs.image_virgin_ring_buffer = tmp;
+					cnt->imgs.image_virgin_ring_size = new_virgin_size;
+				}
+			}
+		}
+
 		/* Get time for current frame */
 		cnt->currenttime = time(NULL);
 
@@ -891,6 +921,21 @@
 			/* newimg points to position in ring where to store image */
 			newimg = cnt->imgs.image_ring_buffer + (cnt->imgs.size * cnt->imgs.ring_buffer_last_in);
 
+			/* Update pos in virgin ring buffer */
+			if (++cnt->imgs.image_virgin_ring_last_in >= cnt->imgs.image_virgin_ring_size) {
+				cnt->imgs.image_virgin_ring_last_in = 0;
+			}
+
+			/* Update end (oldest) pos */
+			if (cnt->imgs.image_virgin_ring_last_in == cnt->imgs.image_virgin_ring_referense_image_out) {
+				cnt->imgs.image_virgin_ring_referense_image_out = cnt->imgs.image_virgin_ring_last_in + 1;				
+				if(cnt->imgs.image_virgin_ring_referense_image_out >= cnt->imgs.image_virgin_ring_size)
+					cnt->imgs.image_virgin_ring_referense_image_out =  0;
+			}
+
+			/* image_virgin points to position in ring where to store image */
+			cnt->imgs.image_virgin = cnt->imgs.image_virgin_ring_buffer + (cnt->imgs.size * cnt->imgs.image_virgin_ring_last_in);
+
 		/***** MOTION LOOP - RETRY INITIALIZING NETCAM SECTION *****/
 			/* If a network camera is not available we keep on retrying every 10 seconds
 			 * until it shows up.
@@ -1307,16 +1352,26 @@
 				 * more accurate.
 				 */
 				memcpy(cnt->imgs.ref, cnt->imgs.image_virgin, cnt->imgs.size);
+				cnt->imgs.image_virgin_ring_referense_image_out = cnt->imgs.image_virgin_ring_last_in;
 			} else if (cnt->threshold) {
-				/* Old image slowly decays, this will make it even harder on
-			 	 * a slow moving object to stay undetected
-			 	 */
-				unsigned char *imgs_ref_ptr = cnt->imgs.ref;
-				unsigned char *newimg_ptr = cnt->imgs.image_virgin;
-				for (i=cnt->imgs.size-1; i>=0; i--) {
-					*imgs_ref_ptr = (*imgs_ref_ptr + *newimg_ptr)/2;
-					imgs_ref_ptr++;
-					newimg_ptr++;
+				if (cnt->imgs.image_virgin_ring_size <= 1 || detecting_motion) {
+					/* Old image slowly decays, this will make it even harder on
+				 	 * a slow moving object to stay undetected
+				 	 */
+					unsigned char *imgs_ref_ptr = cnt->imgs.ref;
+					unsigned char *newimg_ptr = cnt->imgs.image_virgin;
+					for (i=cnt->imgs.size-1; i>=0; i--) {
+						*imgs_ref_ptr = (*imgs_ref_ptr + *newimg_ptr)/2;
+						imgs_ref_ptr++;
+						newimg_ptr++;
+					}
+					cnt->imgs.image_virgin_ring_referense_image_out = cnt->imgs.image_virgin_ring_last_in;
+				} else {
+					/* Take older image as ref. image
+					 */
+					memcpy(cnt->imgs.ref, 
+					       cnt->imgs.image_virgin_ring_buffer + (cnt->imgs.size * cnt->imgs.image_virgin_ring_referense_image_out),
+					       cnt->imgs.size);
 				}
 			}
 
Index: motion.h
===================================================================
--- motion.h	(revision 213)
+++ motion.h	(working copy)
@@ -209,6 +209,12 @@
 	int ring_buffer_size;
 	int ring_buffer_last_in;
 	int ring_buffer_last_out;
+
+	unsigned char *image_virgin_ring_buffer;   /* Ring buffer of image_virgin images, used to delay reference image */
+	int image_virgin_ring_size;                /* Size of the ring buffer */
+	int image_virgin_ring_last_in;             /* Last inserted */
+	int image_virgin_ring_referense_image_out; /* Oldest image */
+
 	unsigned char *ref;               /* The reference frame */
 	unsigned char *out;               /* Picture buffer for motion images */
 	unsigned char *image_virgin;      /* Last picture frame with no text or locate overlay */