diff --git a/Changelog b/Changelog
index 223e127..240b691 100644
--- a/Changelog
+++ b/Changelog
@@ -12,6 +12,11 @@
 		are: point, line, rectangle, ellipse (circle), text.
 		Translucency (alpha) is supported, although for ellipses, it does not
 		work as expected (due to a bug in libgd)
+	- A default color can be specified for invisible/undefined nodes in rendered
+		blocks Normally, such nodes are not drawn, so they have the background
+		color; If a different default color is specified, undefined/invisible
+		nodes in defined blocks get the default color, and can be distinguished
+		from undefined blocks (which still have the regular background color).
 
     Enhancements:
     	- Failure to process a command-line option now causes a specific error message.
diff --git a/README.rst b/README.rst
index 32f3d72..0dcdc98 100644
--- a/README.rst
+++ b/README.rst
@@ -137,6 +137,13 @@ colors <file>:
 bgcolor:
     Background color of image, `--bgcolor #ffffff`
 
+blockcolor:
+    Default color of nodes in blocks that are in the database, `--blockcolor #ffffff`
+
+    If a block is in the database, but some of its nodes are not visible (because they are
+    air, or 'invalid', the nodes are drawn in this color (as opposed to the background
+    color, which shows for blocks that are not in the database)
+
 scalecolor:
     Color of scale, `--scalecolor #000000`
 
diff --git a/TileGenerator.cpp b/TileGenerator.cpp
index 07afe57..5f078c5 100644
--- a/TileGenerator.cpp
+++ b/TileGenerator.cpp
@@ -122,6 +122,7 @@ TileGenerator::TileGenerator():
 	verboseStatistics(false),
 	progressIndicator(false),
 	m_bgColor(255, 255, 255),
+	m_blockDefaultColor(0, 0, 0, 0),
 	m_scaleColor(0, 0, 0),
 	m_originColor(255, 0, 0),
 	m_playerColor(255, 0, 0),
@@ -175,6 +176,13 @@ void TileGenerator::setBgColor(const Color &bgColor)
 	m_bgColor = bgColor;
 }
 
+void TileGenerator::setBlockDefaultColor(const Color &color)
+{
+	m_blockDefaultColor = color;
+	// Any value will do, except for 0
+	m_blockDefaultColor.a = 1;
+}
+
 void TileGenerator::setShrinkGeometry(bool shrink)
 {
 	m_shrinkGeometry = shrink;
@@ -801,7 +809,7 @@ void TileGenerator::pushPixelRows(int zPosLimit) {
 			{ int ix = mapX2ImageX(mapX); assert(ix - m_border >= 0 && ix - m_border < m_pictWidth); }
 			{ int iy = mapY2ImageY(mapY); assert(iy - m_border >= 0 && iy - m_border < m_pictHeight); }
 #endif
-			if (pixel.is_valid())
+			if (pixel.is_valid() || pixel.color().to_uint())
 				m_image->tpixels[mapY2ImageY(mapY)][mapX2ImageX(mapX)] = pixel.color().to_libgd();
 		}
 	}
@@ -1203,6 +1211,11 @@ inline void TileGenerator::renderMapBlock(const ustring &mapBlock, const BlockPo
 			if (m_readedPixels[z] & (1 << x)) {
 				continue;
 			}
+			if (m_blockDefaultColor.to_uint() && !m_blockPixelAttributes.attribute(zBegin + 15 - z,xBegin + x).color().to_uint()) {
+				PixelAttribute pixel = PixelAttribute(m_blockDefaultColor, NAN);
+				m_blockPixelAttributes.attribute(zBegin + 15 - z,xBegin + x) = pixel;
+				rowIsEmpty = false;
+			}
 			for (int y = maxY; y >= minY; --y) {
 				int position = x + (y << 4) + (z << 8);
 				int content = readBlockContent(mapData, version, position);
diff --git a/TileGenerator.h b/TileGenerator.h
index af2679b..872e8d1 100644
--- a/TileGenerator.h
+++ b/TileGenerator.h
@@ -83,6 +83,7 @@ public:
 	TileGenerator();
 	~TileGenerator();
 	void setBgColor(const Color &bgColor);
+	void setBlockDefaultColor(const Color &olor);
 	void setScaleColor(const Color &scaleColor);
 	void setOriginColor(const Color &originColor);
 	void setPlayerColor(const Color &playerColor);
@@ -159,6 +160,7 @@ public:
 
 private:
 	Color m_bgColor;
+	Color m_blockDefaultColor;
 	Color m_scaleColor;
 	Color m_originColor;
 	Color m_playerColor;
diff --git a/mapper.cpp b/mapper.cpp
index b260716..d30cfaa 100644
--- a/mapper.cpp
+++ b/mapper.cpp
@@ -25,6 +25,7 @@ using namespace std;
 #define OPT_SQLITE_CACHEWORLDROW	0x81
 #define OPT_PROGRESS_INDICATOR		0x82
 #define OPT_DRAW_OBJECT			0x83
+#define OPT_BLOCKCOLOR			0x84
 #define OPT_VERBOSE_SEARCH_COLORS	0x86
 
 // Will be replaced with the actual name and location of the executable (if found)
@@ -61,6 +62,7 @@ void usage()
 			"  -o/--output <output_image.png>\n"
 			"  --colors <file>\n"
 			"  --bgcolor <color>\n"
+			"  --blockcolor <color>\n"
 			"  --scalecolor <color>\n"
 			"  --playercolor <color>\n"
 			"  --origincolor <color>\n"
@@ -516,6 +518,7 @@ int main(int argc, char *argv[])
 		{"output", required_argument, 0, 'o'},
 		{"colors", required_argument, 0, 'C'},
 		{"bgcolor", required_argument, 0, 'b'},
+		{"blockcolor", required_argument, 0, OPT_BLOCKCOLOR},
 		{"scalecolor", required_argument, 0, 's'},
 		{"origincolor", required_argument, 0, 'r'},
 		{"playercolor", required_argument, 0, 'p'},
@@ -596,6 +599,9 @@ int main(int argc, char *argv[])
 				case 'b':
 					generator.setBgColor(Color(optarg, 0));
 					break;
+				case OPT_BLOCKCOLOR:
+					generator.setBlockDefaultColor(Color(optarg, 0));
+					break;
 				case 's':
 					generator.setScaleColor(Color(optarg,0));
 					break;