diff --git a/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/v1/SimpleImageDataConfig.java b/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/v1/SimpleImageDataConfig.java
index f77457cafb5694bf4dd16126b8cd7dfae5af9cdc..9a58eb515ad07b1df078e52adbf8bde6e59f5ae7 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/v1/SimpleImageDataConfig.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/v1/SimpleImageDataConfig.java
@@ -59,8 +59,10 @@ abstract public class SimpleImageDataConfig
     public ImageMetadata[] extractImagesMetadata(String imagePath,
             List<ImageIdentifier> imageIdentifiers)
     {
-        return new ImageMetadata[]
-            { extractImageMetadata(imagePath) };
+
+        ImageMetadata imageMetadata = extractImageMetadata(imagePath);
+        return (imageMetadata != null) ? new ImageMetadata[]
+            { imageMetadata } : new ImageMetadata[0];
     }
 
     // --- methods which can be overridden -----------------
diff --git a/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/jython/SimpleImageDataSetRegistrator.java b/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/jython/SimpleImageDataSetRegistrator.java
index d7317e792d357682d81e0827b6cf4880cb312c88..b7a5cbb1b2bf9cc6c57553b97973719b8c696470 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/jython/SimpleImageDataSetRegistrator.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/dss/etl/jython/SimpleImageDataSetRegistrator.java
@@ -179,10 +179,8 @@ public class SimpleImageDataSetRegistrator
                     simpleImageConfig.extractImagesMetadata(imageRelativePath, identifiers);
             for (ImageMetadata imageToken : imageTokens)
             {
-                if (imageToken != null) {
-                    imageToken.ensureValid(simpleImageConfig.isMicroscopyData());
-                    imageTokensList.add(new ImageTokensWithPath(imageToken, imageRelativePath));
-                }
+                imageToken.ensureValid(simpleImageConfig.isMicroscopyData());
+                imageTokensList.add(new ImageTokensWithPath(imageToken, imageRelativePath));
             }
         }
         if (imageTokensList.size() == 0)