diff --git a/simutrans/trunk/display/simgraph16.cc b/simutrans/trunk/display/simgraph16.cc
index 8ee1145..f3f5e36 100644
--- a/simutrans/trunk/display/simgraph16.cc
+++ b/simutrans/trunk/display/simgraph16.cc
@@ -1599,17 +1599,20 @@ static void rezoom_img(const image_id n)
 							sint16 xreal2 = ((x * zoom_den[zoom_factor] + 1 - x_rem) / zoom_num[zoom_factor]) * 4;
 							SumSubpixel( p1 + xreal1 );
 							SumSubpixel( p1 + xreal2 );
+							uint8 sum = valid; // valid pixels in top row
 							SumSubpixel( p2 + xreal1 );
 							SumSubpixel( p2 + xreal2 );
-							if(  valid == 0  ) {
-								*dest++ = 0x73FE;
-							}
-							else if(  valid == 255  ) {
+							sum += valid; // = 2*(pixels in top row) + (pixels in bottom row)
+							if(  valid == 255  ) { // special color
 								*dest++ = (0x8000 | r) + (((uint16)g)<<5) + (((uint16)b)<<10);
 							}
-							else {
+							else if (sum >=3) { // maximal possible sum / 2 - 1, determined by hand
+								// two pixels in top row or at least one pixel in each row
 								*dest++ = (r/valid) + (((uint16)(g/valid))<<5) + (((uint16)(b/valid))<<10);
 							}
+							else {
+								*dest++ = 0x73FE;
+							}
 						}
 					}
 					break;
@@ -1627,21 +1630,24 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p1 + xreal1 );
 							SumSubpixel( p1 + xreal2 );
 							SumSubpixel( p1 + xreal3 );
+							uint8 sum = valid;
 							SumSubpixel( p2 + xreal1 );
 							SumSubpixel( p2 + xreal2 );
 							SumSubpixel( p2 + xreal3 );
+							sum += valid;
 							SumSubpixel( p3 + xreal1 );
 							SumSubpixel( p3 + xreal2 );
 							SumSubpixel( p3 + xreal3 );
-							if(  valid == 0  ) {
-								*dest++ = 0x73FE;
-							}
-							else if(  valid == 255  ) {
+							sum += valid; // = 3*(pixels in top row) + 2*(pixels in mid row) + (pixels in bottom row)
+							if(  valid == 255  ) {
 								*dest++ = (0x8000 | r) + (((uint16)g)<<5) + (((uint16)b)<<10);
 							}
-							else {
+							else if (sum >= 8) { // maximal possible sum / 2 - 1, determined by hand
 								*dest++ = (r/valid) | (((uint16)(g/valid))<<5) | (((uint16)(b/valid))<<10);
 							}
+							else {
+								*dest++ = 0x73FE;
+							}
 						}
 					}
 					break;
@@ -1662,27 +1668,31 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p1 + xreal2 );
 							SumSubpixel( p1 + xreal3 );
 							SumSubpixel( p1 + xreal4 );
+							uint8 sum = valid;
 							SumSubpixel( p2 + xreal1 );
 							SumSubpixel( p2 + xreal2 );
 							SumSubpixel( p2 + xreal3 );
 							SumSubpixel( p2 + xreal4 );
+							sum += valid;
 							SumSubpixel( p3 + xreal1 );
 							SumSubpixel( p3 + xreal2 );
 							SumSubpixel( p3 + xreal3 );
 							SumSubpixel( p3 + xreal4 );
+							sum += valid;
 							SumSubpixel( p4 + xreal1 );
 							SumSubpixel( p4 + xreal2 );
 							SumSubpixel( p4 + xreal3 );
 							SumSubpixel( p4 + xreal4 );
-							if(  valid == 0  ) {
-								*dest++ = 0x73FE;
-							}
-							else if(  valid == 255  ) {
+							sum += valid;
+							if(  valid == 255  ) {
 								*dest++ = (0x8000 | r) + (((uint16)g)<<5) + (((uint16)b)<<10);
 							}
-							else {
+							else if (sum >= 19) { // maximal possible sum / 2 - 1, worked by chance
 								*dest++ = (r/valid) | (((uint16)(g/valid))<<5) | (((uint16)(b/valid))<<10);
 							}
+							else {
+								*dest++ = 0x73FE;
+							}
 						}
 					}
 					break;
@@ -1715,6 +1725,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p1 + xreal6 );
 							SumSubpixel( p1 + xreal7 );
 							SumSubpixel( p1 + xreal8 );
+							uint16 sum = valid;
 							SumSubpixel( p2 + xreal1 );
 							SumSubpixel( p2 + xreal2 );
 							SumSubpixel( p2 + xreal3 );
@@ -1723,6 +1734,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p2 + xreal6 );
 							SumSubpixel( p2 + xreal7 );
 							SumSubpixel( p2 + xreal8 );
+							sum += valid;
 							SumSubpixel( p3 + xreal1 );
 							SumSubpixel( p3 + xreal2 );
 							SumSubpixel( p3 + xreal3 );
@@ -1731,6 +1743,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p3 + xreal6 );
 							SumSubpixel( p3 + xreal7 );
 							SumSubpixel( p3 + xreal8 );
+							sum += valid;
 							SumSubpixel( p4 + xreal1 );
 							SumSubpixel( p4 + xreal2 );
 							SumSubpixel( p4 + xreal3 );
@@ -1739,6 +1752,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p4 + xreal6 );
 							SumSubpixel( p4 + xreal7 );
 							SumSubpixel( p4 + xreal8 );
+							sum += valid;
 							SumSubpixel( p5 + xreal1 );
 							SumSubpixel( p5 + xreal2 );
 							SumSubpixel( p5 + xreal3 );
@@ -1747,6 +1761,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p5 + xreal6 );
 							SumSubpixel( p5 + xreal7 );
 							SumSubpixel( p5 + xreal8 );
+							sum += valid;
 							SumSubpixel( p6 + xreal1 );
 							SumSubpixel( p6 + xreal2 );
 							SumSubpixel( p6 + xreal3 );
@@ -1755,6 +1770,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p6 + xreal6 );
 							SumSubpixel( p6 + xreal7 );
 							SumSubpixel( p6 + xreal8 );
+							sum += valid;
 							SumSubpixel( p7 + xreal1 );
 							SumSubpixel( p7 + xreal2 );
 							SumSubpixel( p7 + xreal3 );
@@ -1763,6 +1779,7 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p7 + xreal6 );
 							SumSubpixel( p7 + xreal7 );
 							SumSubpixel( p7 + xreal8 );
+							sum += valid;
 							SumSubpixel( p8 + xreal1 );
 							SumSubpixel( p8 + xreal2 );
 							SumSubpixel( p8 + xreal3 );
@@ -1771,15 +1788,18 @@ static void rezoom_img(const image_id n)
 							SumSubpixel( p8 + xreal6 );
 							SumSubpixel( p8 + xreal7 );
 							SumSubpixel( p8 + xreal8 );
-							if(  valid == 0  ) {
-								*dest++ = 0x73FE;
-							}
-							else if(  valid == 255  ) {
+							sum += valid;
+							if(  valid == 255  ) {
 								*dest++ = (0x8000 | r) + (((uint16)g)<<5) + (((uint16)b)<<10);
 							}
-							else {
+							else if (sum >= 143 + 5) {
+								// maximal possible sum / 2 - 1 + extra 5
+								// determined by experimenting with pak192.comic
 								*dest++ = (r/valid) | (((uint16)(g/valid))<<5) | (((uint16)(b/valid))<<10);
 							}
+							else {
+								*dest++ = 0x73FE;
+							}
 						}
 					}
 					break;