Fix bug with low number of frames and frame rate reduction

src/main/java/org/mastodon/mamut/segment/SegmentUsingEllipsoidsController.java

@@ -111,7 +111,9 @@ public void saveEllipsoidSegmentationToFile(
 		logger.info( "Save ellipsoid segmentation to file. Label options: {}, file: {}", labelOption, file.getAbsolutePath() );
 		long[] spatialDimensions = getDimensionsOfSource();
 		int numTimePoints = timePoints.size();
-		int frames = numTimePoints / frameRateReduction + 1;
+		int frames = numTimePoints / frameRateReduction;
+		if ( numTimePoints > frameRateReduction )
+			frames++;
 		logger.debug(
 				"number of timepoints: {}, frame rate reduction: {}, resulting frames: {}", numTimePoints, frameRateReduction, frames );
 		DiskCachedCellImg< IntType, ? > img = createCachedImage( spatialDimensions, frames );

src/test/java/org/mastodon/mamut/segment/SegmentUsingEllipsoidsControllerTest.java

@@ -29,6 +29,7 @@
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThrows;
 
 public class SegmentUsingEllipsoidsControllerTest
@@ -80,6 +81,11 @@ public void testSaveEllipsoidSegmentationToFile() throws IOException
 		SCIFIOImgPlus< IntType > imgTrack = getIntTypeSCIFIOImgPlus( imgOpener, outputTrack );
 
 		// check that the spot id / branchSpot id / track id is used as value in the center of the spot
+		assertNotNull( imgSpot );
+		assertEquals( 3, imgSpot.dimensionsAsLongArray().length );
+		assertEquals( 100, imgSpot.dimension( 0 ) );
+		assertEquals( 100, imgSpot.dimension( 1 ) );
+		assertEquals( 100, imgSpot.dimension( 2 ) );
 		assertEquals( spot.getInternalPoolIndex() + SegmentUsingEllipsoidsController.LABEL_ID_OFFSET, imgSpot.getAt( center ).get() );
 		assertEquals(
 				branchSpot.getInternalPoolIndex() + SegmentUsingEllipsoidsController.LABEL_ID_OFFSET, imgBranchSpot.getAt( center ).get() );