diff --git a/corelib/include/rtabmap/core/Signature.h b/corelib/include/rtabmap/core/Signature.h
index b5e52588..72035196 100644
--- a/corelib/include/rtabmap/core/Signature.h
+++ b/corelib/include/rtabmap/core/Signature.h
@@ -140,7 +140,8 @@ public:
 
 	SensorData toSensorData();
 	void uncompressData();
-	void uncompressData(cv::Mat * imageRaw, cv::Mat * depthRaw, cv::Mat * depth2DRaw) const;
+	void uncompressData(cv::Mat * imageRaw, cv::Mat * depthRaw, cv::Mat * depth2DRaw);
+	void uncompressDataConst(cv::Mat * imageRaw, cv::Mat * depthRaw, cv::Mat * depth2DRaw) const;
 
 private:
 	int _id;
diff --git a/corelib/src/Signature.cpp b/corelib/src/Signature.cpp
index 3ce57b04..a84bf03c 100644
--- a/corelib/src/Signature.cpp
+++ b/corelib/src/Signature.cpp
@@ -247,7 +247,24 @@ void Signature::uncompressData()
 	uncompressData(&_imageRaw, &_depthRaw, &_depth2DRaw);
 }
 
-void Signature::uncompressData(cv::Mat * imageRaw, cv::Mat * depthRaw, cv::Mat * depth2DRaw) const
+void Signature::uncompressData(cv::Mat * imageRaw, cv::Mat * depthRaw, cv::Mat * depth2DRaw)
+{
+	uncompressDataConst(imageRaw, depthRaw, depth2DRaw);
+	if(imageRaw && !imageRaw->empty() && _imageRaw.empty())
+	{
+		_imageRaw = *imageRaw;
+	}
+	if(depthRaw && !depthRaw->empty() && _depthRaw.empty())
+	{
+		_depthRaw = *depthRaw;
+	}
+	if(depth2DRaw && !depth2DRaw->empty() && _depth2DRaw.empty())
+	{
+		_depth2DRaw = *depth2DRaw;
+	}
+}
+
+void Signature::uncompressDataConst(cv::Mat * imageRaw, cv::Mat * depthRaw, cv::Mat * depth2DRaw) const
 {
 	if(imageRaw)
 	{
diff --git a/guilib/src/MainWindow.cpp b/guilib/src/MainWindow.cpp
index 3339b20b..b2cf7732 100644
--- a/guilib/src/MainWindow.cpp
+++ b/guilib/src/MainWindow.cpp
@@ -4294,7 +4294,7 @@ pcl::PointCloud<pcl::PointXYZRGB>::Ptr MainWindow::getAssembledCloud(
 			{
 				const Signature & s = _cachedSignatures.find(iter->first).value();
 				cv::Mat image, depth;
-				s.uncompressData(&image, &depth, 0);
+				s.uncompressDataConst(&image, &depth, 0);
 				pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud;
 				if(regenerateClouds)
 				{
@@ -4380,7 +4380,7 @@ std::map<int, pcl::PointCloud<pcl::PointXYZRGB>::Ptr > MainWindow::getClouds(
 			{
 				const Signature & s = _cachedSignatures.find(iter->first).value();
 				cv::Mat image, depth;
-				s.uncompressData(&image, &depth, 0);
+				s.uncompressDataConst(&image, &depth, 0);
 				pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud;
 				if(regenerateClouds)
 				{
diff --git a/guilib/src/PdfPlot.cpp b/guilib/src/PdfPlot.cpp
index 98afcbb8..59630be8 100644
--- a/guilib/src/PdfPlot.cpp
+++ b/guilib/src/PdfPlot.cpp
@@ -73,11 +73,14 @@ void PdfPlotItem::showDescription(bool shown)
 			if(iter != _signaturesRef->constEnd() && !iter.value().getImageCompressed().empty())
 			{
 				cv::Mat image;
-				iter.value().uncompressData(&image, 0, 0);
-				img = uCvMat2QImage(iter.value().getImageRaw());
-				QPixmap scaled = QPixmap::fromImage(img).scaledToWidth(128);
-				_img = new QGraphicsPixmapItem(scaled, this);
-				_img->setVisible(false);
+				iter.value().uncompressDataConst(&image, 0, 0);
+				if(!image.empty())
+				{
+					img = uCvMat2QImage(image);
+					QPixmap scaled = QPixmap::fromImage(img).scaledToWidth(128);
+					_img = new QGraphicsPixmapItem(scaled, this);
+					_img->setVisible(false);
+				}
 			}
 		}