diff --git a/screening/resource/test-data/ConvertToolImageTransformerTest/pond-transformed.png b/screening/resource/test-data/ConvertToolImageTransformerTest/pond-transformed.png
index 6b41b07cde5e588e2bf182ee759e4d2b1967b131..6d0b6a81ecb63b6625d586c3e2a4fb2a9f492190 100644
Binary files a/screening/resource/test-data/ConvertToolImageTransformerTest/pond-transformed.png and b/screening/resource/test-data/ConvertToolImageTransformerTest/pond-transformed.png differ
diff --git a/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/transformations/ConvertToolImageTransformerTest.java b/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/transformations/ConvertToolImageTransformerTest.java
index ecb3efca5bbae3eae841a9153283a6461f19bab5..07768ba969c854c6661cfb7f25d348fdd4ddc907 100644
--- a/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/transformations/ConvertToolImageTransformerTest.java
+++ b/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/etl/dto/api/transformations/ConvertToolImageTransformerTest.java
@@ -34,7 +34,7 @@ public class ConvertToolImageTransformerTest extends AssertJUnit
     private final String IMAGE_FOLDER = "./resource/test-data/" + getClass().getSimpleName();
 
     private final String CONVERT_PARAMS =
-            " -contrast-stretch 0 -edge 1 -threshold 1 -transparent black ";
+            " -contrast-stretch 0 -edge 1 -threshold 1 -transparent white ";
 
     @Test(groups = "slow")
     public void testTransformation()