Allow to override min_size via command-line argument

src/main/java/com/glencoesoftware/bioformats2raw/Converter.java

@@ -361,6 +361,15 @@ public class Converter implements Callable<Void> {
   )
   private volatile boolean reuseExistingResolutions = false;
 
+  @Option(
+      names = "--min-size",
+      description = "Minimum size of the largest XY dimension in the" +
+          "smallest resolution, when calculating the number of resolutions" +
+          " generate."
+  )
+  private volatile int minSize = MIN_SIZE;
+
+
   /** Scaling implementation that will be used during downsampling. */
   private volatile IImageScaler scaler = new SimpleImageScaler();
 
@@ -1113,7 +1122,7 @@ public void saveResolutions(int series)
         else {
           int width = workingReader.getSizeX();
           int height = workingReader.getSizeY();
-          while (width > MIN_SIZE || height > MIN_SIZE) {
+          while (width > minSize || height > minSize) {
             resolutions++;
             width /= PYRAMID_SCALE;
             height /= PYRAMID_SCALE;

src/test/java/com/glencoesoftware/bioformats2raw/test/ZarrTest.java

@@ -1206,6 +1206,29 @@ public void testChunkSizeToBig() throws Exception {
     }
   }
 
+  /**
+   * Convert an image with the --min-size option.
+   */
+  @Test
+  public void testMinSizeOption() throws Exception {
+    input = fake();
+    assertTool("--min-size", "32");
+
+    ZarrGroup z = ZarrGroup.open(output.resolve("0").toString());
+    List<Map<String, Object>> multiscales = (List<Map<String, Object>>)
+            z.getAttributes().get("multiscales");
+
+    Map<String, Object> multiscale = multiscales.get(0);
+    List<Map<String, Object>> datasets =
+              (List<Map<String, Object>>) multiscale.get("datasets");
+
+    String lastPath = (String) datasets.get(datasets.size()  - 1).get("path");
+    ZarrArray lastArray = z.openArray(lastPath);
+
+    assert lastArray.getShape()[0] < 32;
+    assert lastArray.getShape()[1] < 32;
+  }
+
   private void checkPlateGroupLayout(Path root, int rowCount, int colCount,
     int fieldCount, int x, int y)
     throws IOException