Metamorph: prevent NumberFormatException when trying to read waveleng…

…th in nm

Fixes #4273.

components/formats-gpl/src/loci/formats/in/MetamorphHandler.java

@@ -34,6 +34,9 @@
 import ome.units.UNITS;
 import ome.units.quantity.Length;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import org.xml.sax.Attributes;
 
 /**
@@ -45,6 +48,9 @@
  */
 public class MetamorphHandler extends BaseHandler {
 
+  private static final Logger LOGGER =
+    LoggerFactory.getLogger(MetamorphHandler.class);
+
   // -- Fields --
 
   private Hashtable metadata;
@@ -256,7 +262,15 @@ else if (key.equals("stage-position-y")) {
       }
     }
     if (key.equals("wavelength")) {
-      wavelengths.add(Integer.parseInt(value));
+      // usually this key represents an integer wavelength in nm
+      // sometimes it can be a more descriptive string with no
+      // usable value in nm
+      try {
+        wavelengths.add(Integer.parseInt(value));
+      }
+      catch (NumberFormatException e) {
+        LOGGER.debug("Could not parse wavelength value from {}", value);
+      }
     }
     else if (key.equals("acquisition-time-local")) {
       date = value;