From 706a2222cd44341742e22f05cbcd47e227736f14 Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Sat, 5 Jan 2019 11:51:02 -0800
Subject: [PATCH 01/11] add java example

---
 .../org/apache/mxnet/javaapi/Image.scala      | 96 +++++++++++++++++++
 .../infer/predictor/PredictorExample.java     | 77 +--------------
 2 files changed, 98 insertions(+), 75 deletions(-)
 create mode 100644 scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala

diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
new file mode 100644
index 000000000000..9276452c3ba0
--- /dev/null
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
@@ -0,0 +1,96 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.mxnet.javaapi
+// scalastyle:off
+import java.awt.image.BufferedImage
+// scalastyle:on
+import java.io.InputStream
+
+object Image {
+  /**
+    * Decode image with OpenCV.
+    * Note: return image in RGB by default, instead of OpenCV's default BGR.
+    * @param buf    Buffer containing binary encoded image
+    * @param flag   Convert decoded image to grayscale (0) or color (1).
+    * @param toRGB Whether to convert decoded image
+    *               to mxnet's default RGB format (instead of opencv's default BGR).
+    * @return NDArray in HWC format
+    */
+  def imDecode(buf: Array[Byte], flag: Int, toRGB: Boolean, out: NDArray): NDArray = {
+    org.apache.mxnet.Image.imDecode(buf, flag, toRGB, Some(out))
+  }
+
+  /**
+    * Same imageDecode with InputStream
+    * @param inputStream the inputStream of the image
+    * @return NDArray in HWC format
+    */
+  def imDecode(inputStream: InputStream, flag: Int = 1, toRGB: Boolean = true,
+               out: NDArray): NDArray = {
+    org.apache.mxnet.Image.imDecode(inputStream, flag, toRGB, Some(out))
+  }
+
+  /**
+    * Read and decode image with OpenCV.
+    * Note: return image in RGB by default, instead of OpenCV's default BGR.
+    * @param filename Name of the image file to be loaded.
+    * @param flag     Convert decoded image to grayscale (0) or color (1).
+    * @param toRGB   Whether to convert decoded image to mxnet's default RGB format
+    *                 (instead of opencv's default BGR).
+    * @return org.apache.mxnet.NDArray in HWC format
+    */
+  def imRead(filename: String, flag: Int, toRGB: Boolean = true, out: NDArray): NDArray = {
+    org.apache.mxnet.Image.imRead(filename, Some(flag), Some(toRGB), Some(out))
+  }
+
+  /**
+    * Resize image with OpenCV.
+    * @param src     source image in NDArray
+    * @param w       Width of resized image.
+    * @param h       Height of resized image.
+    * @param interp  Interpolation method (default=cv2.INTER_LINEAR).
+    * @return org.apache.mxnet.NDArray
+    */
+  def imResize(src: NDArray, w: Int, h: Int,
+               interp: Integer, out: NDArray): NDArray = {
+    org.apache.mxnet.Image.imResize(src, w, h, Some(interp), Some(out))
+  }
+
+  /**
+    * Do a fixed crop on the image
+    * @param src Src image in NDArray
+    * @param x0 starting x point
+    * @param y0 starting y point
+    * @param w width of the image
+    * @param h height of the image
+    * @return cropped NDArray
+    */
+  def fixedCrop(src: NDArray, x0: Int, y0: Int, w: Int, h: Int): NDArray = {
+    org.apache.mxnet.Image.fixedCrop(src, x0, y0, w, h)
+  }
+
+  /**
+    * Convert a NDArray image to a real image
+    * The time cost will increase if the image resolution is big
+    * @param src Source image file in RGB
+    * @return Buffered Image
+    */
+  def toImage(src: NDArray): BufferedImage = {
+    org.apache.mxnet.Image.toImage(src)
+  }
+}
diff --git a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
index c9b4426f52b3..d89835c8dcaa 100644
--- a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
+++ b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
@@ -24,8 +24,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import javax.imageio.ImageIO;
-import java.awt.Graphics2D;
 import java.awt.image.BufferedImage;
 import java.io.BufferedReader;
 import java.io.File;
@@ -48,76 +46,6 @@ public class PredictorExample {
 
     final static Logger logger = LoggerFactory.getLogger(PredictorExample.class);
 
-    /**
-     * Load the image from file to buffered image
-     * It can be replaced by loadImageFromFile from ObjectDetector
-     * @param inputImagePath input image Path in String
-     * @return Buffered image
-     */
-    private static BufferedImage loadIamgeFromFile(String inputImagePath) {
-        BufferedImage buf = null;
-        try {
-            buf = ImageIO.read(new File(inputImagePath));
-        } catch (IOException e) {
-            System.err.println(e);
-        }
-        return buf;
-    }
-
-    /**
-     * Reshape the current image using ImageIO and Graph2D
-     * It can be replaced by reshapeImage from ObjectDetector
-     * @param buf Buffered image
-     * @param newWidth desired width
-     * @param newHeight desired height
-     * @return a reshaped bufferedImage
-     */
-    private static BufferedImage reshapeImage(BufferedImage buf, int newWidth, int newHeight) {
-        BufferedImage resizedImage = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
-        Graphics2D g = resizedImage.createGraphics();
-        g.drawImage(buf, 0, 0, newWidth, newHeight, null);
-        g.dispose();
-        return resizedImage;
-    }
-
-    /**
-     * Convert an image from a buffered image into pixels float array
-     * It can be replaced by bufferedImageToPixels from ObjectDetector
-     * @param buf buffered image
-     * @return Float array
-     */
-    private static float[] imagePreprocess(BufferedImage buf) {
-        // Get height and width of the image
-        int w = buf.getWidth();
-        int h = buf.getHeight();
-
-        // get an array of integer pixels in the default RGB color mode
-        int[] pixels = buf.getRGB(0, 0, w, h, null, 0, w);
-
-        // 3 times height and width for R,G,B channels
-        float[] result = new float[3 * h * w];
-
-        int row = 0;
-        // copy pixels to array vertically
-        while (row < h) {
-            int col = 0;
-            // copy pixels to array horizontally
-            while (col < w) {
-                int rgb = pixels[row * w + col];
-                // getting red color
-                result[0 * h * w + row * w + col] = (rgb >> 16) & 0xFF;
-                // getting green color
-                result[1 * h * w + row * w + col] = (rgb >> 8) & 0xFF;
-                // getting blue color
-                result[2 * h * w + row * w + col] = rgb & 0xFF;
-                col += 1;
-            }
-            row += 1;
-        }
-        buf.flush();
-        return result;
-    }
-
     /**
      * Helper class to print the maximum prediction result
      * @param probabilities The float array of probability
@@ -170,9 +98,8 @@ public static void main(String[] args) {
         inputDesc.add(new DataDesc("data", inputShape, DType.Float32(), "NCHW"));
         Predictor predictor = new Predictor(inst.modelPathPrefix, inputDesc, context,0);
         // Prepare data
-        BufferedImage img = loadIamgeFromFile(inst.inputImagePath);
-
-        img = reshapeImage(img, 224, 224);
+        NDArray img = Image.imRead(inst.inputImagePath, 1, true, null);
+        img = Image.imResize(img, 224, 224, null, null);
         // predict
         float[][] result = predictor.predict(new float[][]{imagePreprocess(img)});
         try {

From c7f7e0875ee739f260802e161cdd88e6731c5dfe Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Mon, 7 Jan 2019 16:39:42 -0800
Subject: [PATCH 02/11] add test and change PredictorExample

---
 .../org/apache/mxnet/javaapi/ImageTest.java   | 50 +++++++++++++++++++
 .../infer/predictor/PredictorExample.java     |  7 +--
 2 files changed, 52 insertions(+), 5 deletions(-)
 create mode 100644 scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java

diff --git a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
new file mode 100644
index 000000000000..7a028be30527
--- /dev/null
+++ b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
@@ -0,0 +1,50 @@
+package org.apache.mxnet.javaapi;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import java.io.File;
+import java.net.URL;
+
+public class ImageTest {
+
+    private String imLocation;
+
+    private void downloadUrl(String url, String filePath, int maxRetry) throws Exception{
+        File tmpFile = new File(filePath);
+        Boolean success = false;
+        if (!tmpFile.exists()) {
+            while (maxRetry > 0 && !success) {
+                try {
+                    FileUtils.copyURLToFile(new URL(url), tmpFile);
+                    success = true;
+                } catch(Exception e){
+                   maxRetry -= 1;
+                }
+            }
+        } else {
+            success = true;
+        }
+        if (!success) throw new Exception("$url Download failed!");
+    }
+
+    @BeforeClass
+    public void downloadFile() throws Exception {
+        String tempDirPath = System.getProperty("java.io.tmpdir");
+        imLocation = tempDirPath + "/inputImages/Pug-Cookie.jpg";
+        try {
+            downloadUrl("https://s3.amazonaws.com/model-server/inputs/Pug-Cookie.jpg",
+                    imLocation, 3);
+        } catch (Exception e) {
+            throw e;
+        }
+    }
+
+    @Test
+    public void testImageProcess() {
+        NDArray nd = Image.imRead(imLocation, 1, true, null);
+        NDArray nd2 = Image.imResize(nd, 224, 224, null, null);
+        NDArray cropped = Image.fixedCrop(nd, 0, 0, 224, 224);
+        Image.toImage(cropped);
+    }
+}
diff --git a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
index d89835c8dcaa..a1c3401c2378 100644
--- a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
+++ b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
@@ -101,7 +101,7 @@ public static void main(String[] args) {
         NDArray img = Image.imRead(inst.inputImagePath, 1, true, null);
         img = Image.imResize(img, 224, 224, null, null);
         // predict
-        float[][] result = predictor.predict(new float[][]{imagePreprocess(img)});
+        float[][] result = predictor.predict(new float[][]{img.toArray()});
         try {
             System.out.println("Predict with Float input");
             System.out.println(printMaximumClass(result[0], inst.modelPathPrefix));
@@ -109,10 +109,7 @@ public static void main(String[] args) {
             System.err.println(e);
         }
         // predict with NDArray
-        NDArray nd = new NDArray(
-                imagePreprocess(img),
-                new Shape(new int[]{1, 3, 224, 224}),
-                Context.cpu());
+        NDArray nd = img;
         List<NDArray> ndList = new ArrayList<>();
         ndList.add(nd);
         List<NDArray> ndResult = predictor.predictWithNDArray(ndList);

From 195c5d9ee2cecca7898608f37a8bc1e07796f28f Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Mon, 7 Jan 2019 17:22:39 -0800
Subject: [PATCH 03/11] add image change

---
 .../org/apache/mxnet/javaapi/Image.scala      | 19 +++++++++----------
 .../org/apache/mxnet/javaapi/ImageTest.java   | 14 +++++++++-----
 .../infer/predictor/PredictorExample.java     |  4 ++--
 3 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
index 9276452c3ba0..9d5216cbc862 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
@@ -31,8 +31,8 @@ object Image {
     *               to mxnet's default RGB format (instead of opencv's default BGR).
     * @return NDArray in HWC format
     */
-  def imDecode(buf: Array[Byte], flag: Int, toRGB: Boolean, out: NDArray): NDArray = {
-    org.apache.mxnet.Image.imDecode(buf, flag, toRGB, Some(out))
+  def imDecode(buf: Array[Byte], flag: Int, toRGB: Boolean): NDArray = {
+    org.apache.mxnet.Image.imDecode(buf, flag, toRGB, None)
   }
 
   /**
@@ -40,9 +40,8 @@ object Image {
     * @param inputStream the inputStream of the image
     * @return NDArray in HWC format
     */
-  def imDecode(inputStream: InputStream, flag: Int = 1, toRGB: Boolean = true,
-               out: NDArray): NDArray = {
-    org.apache.mxnet.Image.imDecode(inputStream, flag, toRGB, Some(out))
+  def imDecode(inputStream: InputStream, flag: Int = 1, toRGB: Boolean = true): NDArray = {
+    org.apache.mxnet.Image.imDecode(inputStream, flag, toRGB, None)
   }
 
   /**
@@ -54,8 +53,8 @@ object Image {
     *                 (instead of opencv's default BGR).
     * @return org.apache.mxnet.NDArray in HWC format
     */
-  def imRead(filename: String, flag: Int, toRGB: Boolean = true, out: NDArray): NDArray = {
-    org.apache.mxnet.Image.imRead(filename, Some(flag), Some(toRGB), Some(out))
+  def imRead(filename: String, flag: Int, toRGB: Boolean = true): NDArray = {
+    org.apache.mxnet.Image.imRead(filename, Some(flag), Some(toRGB), None)
   }
 
   /**
@@ -66,9 +65,9 @@ object Image {
     * @param interp  Interpolation method (default=cv2.INTER_LINEAR).
     * @return org.apache.mxnet.NDArray
     */
-  def imResize(src: NDArray, w: Int, h: Int,
-               interp: Integer, out: NDArray): NDArray = {
-    org.apache.mxnet.Image.imResize(src, w, h, Some(interp), Some(out))
+  def imResize(src: NDArray, w: Int, h: Int, interp: Integer): NDArray = {
+    val interpVal = if (interp == null) None else Some(interp.intValue())
+    org.apache.mxnet.Image.imResize(src, w, h, interpVal, None)
   }
 
   /**
diff --git a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
index 7a028be30527..049b1d6156be 100644
--- a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
+++ b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
@@ -6,11 +6,13 @@
 import java.io.File;
 import java.net.URL;
 
+import static org.junit.Assert.assertArrayEquals;
+
 public class ImageTest {
 
-    private String imLocation;
+    private static String imLocation;
 
-    private void downloadUrl(String url, String filePath, int maxRetry) throws Exception{
+    private static void downloadUrl(String url, String filePath, int maxRetry) throws Exception{
         File tmpFile = new File(filePath);
         Boolean success = false;
         if (!tmpFile.exists()) {
@@ -29,7 +31,7 @@ private void downloadUrl(String url, String filePath, int maxRetry) throws Excep
     }
 
     @BeforeClass
-    public void downloadFile() throws Exception {
+    public static void downloadFile() throws Exception {
         String tempDirPath = System.getProperty("java.io.tmpdir");
         imLocation = tempDirPath + "/inputImages/Pug-Cookie.jpg";
         try {
@@ -42,8 +44,10 @@ public void downloadFile() throws Exception {
 
     @Test
     public void testImageProcess() {
-        NDArray nd = Image.imRead(imLocation, 1, true, null);
-        NDArray nd2 = Image.imResize(nd, 224, 224, null, null);
+        NDArray nd = Image.imRead(imLocation, 1, true);
+        assertArrayEquals(nd.shape().toArray(), new int[]{576, 1024, 3});
+        NDArray nd2 = Image.imResize(nd, 224, 224, null);
+        assertArrayEquals(nd.shape().toArray(), new int[]{224, 224, 3});
         NDArray cropped = Image.fixedCrop(nd, 0, 0, 224, 224);
         Image.toImage(cropped);
     }
diff --git a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
index a1c3401c2378..4559315866ba 100644
--- a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
+++ b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
@@ -98,8 +98,8 @@ public static void main(String[] args) {
         inputDesc.add(new DataDesc("data", inputShape, DType.Float32(), "NCHW"));
         Predictor predictor = new Predictor(inst.modelPathPrefix, inputDesc, context,0);
         // Prepare data
-        NDArray img = Image.imRead(inst.inputImagePath, 1, true, null);
-        img = Image.imResize(img, 224, 224, null, null);
+        NDArray img = Image.imRead(inst.inputImagePath, 1, true);
+        img = Image.imResize(img, 224, 224, null);
         // predict
         float[][] result = predictor.predict(new float[][]{img.toArray()});
         try {

From 9ef19b5056f321aa10fd197c50e02970801b4be3 Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Wed, 9 Jan 2019 10:40:22 -0800
Subject: [PATCH 04/11] Add minor fixes

---
 .../core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
index 049b1d6156be..da4911f9a865 100644
--- a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
+++ b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
@@ -47,7 +47,7 @@ public void testImageProcess() {
         NDArray nd = Image.imRead(imLocation, 1, true);
         assertArrayEquals(nd.shape().toArray(), new int[]{576, 1024, 3});
         NDArray nd2 = Image.imResize(nd, 224, 224, null);
-        assertArrayEquals(nd.shape().toArray(), new int[]{224, 224, 3});
+        assertArrayEquals(nd2.shape().toArray(), new int[]{224, 224, 3});
         NDArray cropped = Image.fixedCrop(nd, 0, 0, 224, 224);
         Image.toImage(cropped);
     }

From 016d37424275a3c99775a1f316a759932920230c Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Wed, 9 Jan 2019 11:46:04 -0800
Subject: [PATCH 05/11] add License

---
 .../org/apache/mxnet/javaapi/ImageTest.java     | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
index da4911f9a865..cc284c7c6910 100644
--- a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
+++ b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
@@ -1,3 +1,20 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.apache.mxnet.javaapi;
 
 import org.apache.commons.io.FileUtils;

From f2f7483f725595d75a24e2aeba43dd90e0c97588 Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Fri, 11 Jan 2019 11:23:11 -0800
Subject: [PATCH 06/11] add predictor Example tests

---
 scala-package/examples/pom.xml                |  7 +++
 .../scala/org/apache/mxnetexamples/Util.scala |  4 +-
 .../predictor/PredictorExampleSuite.java      | 50 +++++++++++++++++++
 3 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100644 scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java

diff --git a/scala-package/examples/pom.xml b/scala-package/examples/pom.xml
index 564102a9f696..a41f6cb0aa10 100644
--- a/scala-package/examples/pom.xml
+++ b/scala-package/examples/pom.xml
@@ -15,6 +15,7 @@
 
   <properties>
     <skipTests>true</skipTests>
+    <skipJavaTests>${skipTests}</skipJavaTests>
   </properties>
 
   <build>
@@ -128,5 +129,11 @@
       <artifactId>slf4j-simple</artifactId>
       <version>1.7.5</version>
     </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.11</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>
diff --git a/scala-package/examples/src/main/scala/org/apache/mxnetexamples/Util.scala b/scala-package/examples/src/main/scala/org/apache/mxnetexamples/Util.scala
index c1ff10c6c8a2..dba343160bff 100644
--- a/scala-package/examples/src/main/scala/org/apache/mxnetexamples/Util.scala
+++ b/scala-package/examples/src/main/scala/org/apache/mxnetexamples/Util.scala
@@ -24,9 +24,9 @@ import org.apache.commons.io.FileUtils
 
 object Util {
 
-  def downloadUrl(url: String, filePath: String, maxRetry: Option[Int] = None) : Unit = {
+  def downloadUrl(url: String, filePath: String, maxRetry: Int = 3) : Unit = {
     val tmpFile = new File(filePath)
-    var retry = maxRetry.getOrElse(3)
+    var retry = maxRetry
     var success = false
     if (!tmpFile.exists()) {
       while (retry > 0 && !success) {
diff --git a/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java b/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java
new file mode 100644
index 000000000000..e4cc1c73103a
--- /dev/null
+++ b/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java
@@ -0,0 +1,50 @@
+package org.apache.mxnetexamples.javaapi.infer.predictor;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.apache.mxnetexamples.Util;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+
+public class PredictorExampleSuite {
+
+    final static Logger logger = LoggerFactory.getLogger(PredictorExampleSuite.class);
+    private static String modelPathPrefix = "";
+    private static String inputImagePath = "";
+
+    @BeforeClass
+    public static void downloadFile() {
+        logger.info("Downloading resnet-18 model");
+
+        String tempDirPath = System.getProperty("java.io.tmpdir");
+        logger.info("tempDirPath: %s".format(tempDirPath));
+
+        String baseUrl = "https://s3.us-east-2.amazonaws.com/scala-infer-models";
+
+        Util.downloadUrl(baseUrl + "/resnet-18/resnet-18-symbol.json",
+                tempDirPath + "/resnet18/resnet-18-symbol.json", 3);
+        Util.downloadUrl(baseUrl + "/resnet-18/resnet-18-0000.params",
+                tempDirPath + "/resnet18/resnet-18-0000.params", 3);
+        Util.downloadUrl(baseUrl + "/resnet-18/synset.txt",
+                tempDirPath + "/resnet18/synset.txt", 3);
+        Util.downloadUrl("https://s3.amazonaws.com/model-server/inputs/Pug-Cookie.jpg",
+                tempDirPath + "/inputImages/resnet18/Pug-Cookie.jpg", 3);
+
+        modelPathPrefix = tempDirPath + File.separator + "resnet18/resnet-18";
+        inputImagePath = tempDirPath + File.separator +
+                "inputImages/resnet18/Pug-Cookie.jpg";
+    }
+
+    @Test
+    public void testPredictor(){
+        PredictorExample example = new PredictorExample();
+        String[] args = new String[]{
+                "--model-path-prefix", modelPathPrefix,
+                "--input-image", inputImagePath
+        };
+        example.main(args);
+    }
+
+}

From 79b39e7656d36346f47c6582308af038d837ffc2 Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Mon, 14 Jan 2019 16:01:23 -0800
Subject: [PATCH 07/11] fix the issue with JUnit test

---
 .../core/src/main/scala/org/apache/mxnet/Image.scala        | 6 +++---
 .../core/src/main/scala/org/apache/mxnet/NDArray.scala      | 6 ++++--
 .../src/main/scala/org/apache/mxnet/javaapi/Image.scala     | 6 +++---
 .../javaapi/infer/predictor/PredictorExample.java           | 4 ++++
 ...PredictorExampleSuite.java => PredictorExampleTest.java} | 5 +++--
 .../scala/org/apache/mxnet/javaapi/JavaNDArrayMacro.scala   | 4 ++--
 6 files changed, 19 insertions(+), 12 deletions(-)
 rename scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/{PredictorExampleSuite.java => PredictorExampleTest.java} (95%)

diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala
index 77881ab940be..473cb7c1ae91 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala
@@ -37,7 +37,7 @@ object Image {
     * @param flag   Convert decoded image to grayscale (0) or color (1).
     * @param to_rgb Whether to convert decoded image
     *               to mxnet's default RGB format (instead of opencv's default BGR).
-    * @return NDArray in HWC format
+    * @return NDArray in HWC format with DType uint8
     */
   def imDecode(buf: Array[Byte], flag: Int,
                to_rgb: Boolean,
@@ -56,7 +56,7 @@ object Image {
   /**
     * Same imageDecode with InputStream
     * @param inputStream the inputStream of the image
-    * @return NDArray in HWC format
+    * @return NDArray in HWC format with DType uint8
     */
   def imDecode(inputStream: InputStream, flag: Int = 1,
                to_rgb: Boolean = true,
@@ -78,7 +78,7 @@ object Image {
     * @param flag     Convert decoded image to grayscale (0) or color (1).
     * @param to_rgb   Whether to convert decoded image to mxnet's default RGB format
     *                 (instead of opencv's default BGR).
-    * @return org.apache.mxnet.NDArray in HWC format
+    * @return org.apache.mxnet.NDArray in HWC format with DType uint8
     */
   def imRead(filename: String, flag: Option[Int] = None,
              to_rgb: Option[Boolean] = None,
diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/NDArray.scala b/scala-package/core/src/main/scala/org/apache/mxnet/NDArray.scala
index 5c345f21faf4..4324b3dbe63e 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/NDArray.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/NDArray.scala
@@ -97,9 +97,11 @@ object NDArray extends NDArrayBase {
           case ndArr: Seq[NDArray @unchecked] =>
             if (ndArr.head.isInstanceOf[NDArray]) (ndArr.toArray, ndArr.toArray.map(_.handle))
             else throw new IllegalArgumentException(
-              "Unsupported out var type, should be NDArray or subclass of Seq[NDArray]")
+              s"""Unsupported out ${output.getClass} type,
+                 | should be NDArray or subclass of Seq[NDArray]""".stripMargin)
           case _ => throw new IllegalArgumentException(
-            "Unsupported out var type, should be NDArray or subclass of Seq[NDArray]")
+            s"""Unsupported out ${output.getClass} type,
+               | should be NDArray or subclass of Seq[NDArray]""".stripMargin)
         }
       } else {
         (null, null)
diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
index 9d5216cbc862..531d0b1f96fa 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
@@ -29,7 +29,7 @@ object Image {
     * @param flag   Convert decoded image to grayscale (0) or color (1).
     * @param toRGB Whether to convert decoded image
     *               to mxnet's default RGB format (instead of opencv's default BGR).
-    * @return NDArray in HWC format
+    * @return NDArray in HWC format with DType uint8
     */
   def imDecode(buf: Array[Byte], flag: Int, toRGB: Boolean): NDArray = {
     org.apache.mxnet.Image.imDecode(buf, flag, toRGB, None)
@@ -38,7 +38,7 @@ object Image {
   /**
     * Same imageDecode with InputStream
     * @param inputStream the inputStream of the image
-    * @return NDArray in HWC format
+    * @return NDArray in HWC format with DType uint8
     */
   def imDecode(inputStream: InputStream, flag: Int = 1, toRGB: Boolean = true): NDArray = {
     org.apache.mxnet.Image.imDecode(inputStream, flag, toRGB, None)
@@ -51,7 +51,7 @@ object Image {
     * @param flag     Convert decoded image to grayscale (0) or color (1).
     * @param toRGB   Whether to convert decoded image to mxnet's default RGB format
     *                 (instead of opencv's default BGR).
-    * @return org.apache.mxnet.NDArray in HWC format
+    * @return org.apache.mxnet.NDArray in HWC format with DType uint8
     */
   def imRead(filename: String, flag: Int, toRGB: Boolean = true): NDArray = {
     org.apache.mxnet.Image.imRead(filename, Some(flag), Some(toRGB), None)
diff --git a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
index 4559315866ba..c5d209998d32 100644
--- a/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
+++ b/scala-package/examples/src/main/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExample.java
@@ -45,6 +45,7 @@ public class PredictorExample {
     private String inputImagePath = "/images/dog.jpg";
 
     final static Logger logger = LoggerFactory.getLogger(PredictorExample.class);
+    private static NDArray$ NDArray = NDArray$.MODULE$;
 
     /**
      * Helper class to print the maximum prediction result
@@ -110,6 +111,9 @@ public static void main(String[] args) {
         }
         // predict with NDArray
         NDArray nd = img;
+        nd = NDArray.transpose(nd, new Shape(new int[]{2, 0, 1}), null)[0];
+        nd = NDArray.expand_dims(nd, 0, null)[0];
+        nd = nd.asType(DType.Float32());
         List<NDArray> ndList = new ArrayList<>();
         ndList.add(nd);
         List<NDArray> ndResult = predictor.predictWithNDArray(ndList);
diff --git a/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java b/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java
similarity index 95%
rename from scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java
rename to scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java
index e4cc1c73103a..49656274807d 100644
--- a/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleSuite.java
+++ b/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java
@@ -1,5 +1,6 @@
 package org.apache.mxnetexamples.javaapi.infer.predictor;
 
+import org.junit.Assert;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.apache.mxnetexamples.Util;
@@ -8,9 +9,9 @@
 
 import java.io.File;
 
-public class PredictorExampleSuite {
+public class PredictorExampleTest {
 
-    final static Logger logger = LoggerFactory.getLogger(PredictorExampleSuite.class);
+    final static Logger logger = LoggerFactory.getLogger(PredictorExampleTest.class);
     private static String modelPathPrefix = "";
     private static String inputImagePath = "";
 
diff --git a/scala-package/macros/src/main/scala/org/apache/mxnet/javaapi/JavaNDArrayMacro.scala b/scala-package/macros/src/main/scala/org/apache/mxnet/javaapi/JavaNDArrayMacro.scala
index 4dfd6eb044a1..fa3565b4fb8e 100644
--- a/scala-package/macros/src/main/scala/org/apache/mxnet/javaapi/JavaNDArrayMacro.scala
+++ b/scala-package/macros/src/main/scala/org/apache/mxnet/javaapi/JavaNDArrayMacro.scala
@@ -96,9 +96,9 @@ private[mxnet] object JavaNDArrayMacro extends GeneratorBase {
       // add default out parameter
       argDef += s"out: org.apache.mxnet.javaapi.NDArray"
       if (useParamObject) {
-        impl += "if (po.getOut() != null) map(\"out\") = po.getOut()"
+        impl += "if (po.getOut() != null) map(\"out\") = po.getOut().nd"
       } else {
-        impl += "if (out != null) map(\"out\") = out"
+        impl += "if (out != null) map(\"out\") = out.nd"
       }
       val returnType = "Array[org.apache.mxnet.javaapi.NDArray]"
       // scalastyle:off

From 4c87ea877734f8d5a2aa1ba3171713dc7f3ddbe7 Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Mon, 14 Jan 2019 16:30:38 -0800
Subject: [PATCH 08/11] =?UTF-8?q?Satisfy=20Lint=20God=20=CA=95=20=E2=80=A2?=
 =?UTF-8?q?=E1=B4=A5=E2=80=A2=CA=94?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../infer/predictor/PredictorExampleTest.java  | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java b/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java
index 49656274807d..30bc8db447d8 100644
--- a/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java
+++ b/scala-package/examples/src/test/java/org/apache/mxnetexamples/javaapi/infer/predictor/PredictorExampleTest.java
@@ -1,6 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.apache.mxnetexamples.javaapi.infer.predictor;
 
-import org.junit.Assert;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.apache.mxnetexamples.Util;

From 48b0826c9959f80cfd6c297718e4969d10c0eb3a Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Wed, 16 Jan 2019 11:52:40 -0800
Subject: [PATCH 09/11] update the pom file config

---
 scala-package/core/pom.xml                                | 6 ------
 .../src/test/java/org/apache/mxnet/javaapi/ImageTest.java | 8 ++------
 scala-package/examples/pom.xml                            | 6 ------
 scala-package/infer/pom.xml                               | 8 --------
 scala-package/pom.xml                                     | 6 ++++++
 5 files changed, 8 insertions(+), 26 deletions(-)

diff --git a/scala-package/core/pom.xml b/scala-package/core/pom.xml
index 7264c39e84a0..4de65c0b361a 100644
--- a/scala-package/core/pom.xml
+++ b/scala-package/core/pom.xml
@@ -138,12 +138,6 @@
       <version>INTERNAL</version>
       <scope>provided</scope>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.11</version>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>commons-io</groupId>
       <artifactId>commons-io</artifactId>
diff --git a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
index cc284c7c6910..0092744a21a8 100644
--- a/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
+++ b/scala-package/core/src/test/java/org/apache/mxnet/javaapi/ImageTest.java
@@ -51,12 +51,8 @@ private static void downloadUrl(String url, String filePath, int maxRetry) throw
     public static void downloadFile() throws Exception {
         String tempDirPath = System.getProperty("java.io.tmpdir");
         imLocation = tempDirPath + "/inputImages/Pug-Cookie.jpg";
-        try {
-            downloadUrl("https://s3.amazonaws.com/model-server/inputs/Pug-Cookie.jpg",
-                    imLocation, 3);
-        } catch (Exception e) {
-            throw e;
-        }
+        downloadUrl("https://s3.amazonaws.com/model-server/inputs/Pug-Cookie.jpg",
+                imLocation, 3);
     }
 
     @Test
diff --git a/scala-package/examples/pom.xml b/scala-package/examples/pom.xml
index a41f6cb0aa10..30ccfdcce12e 100644
--- a/scala-package/examples/pom.xml
+++ b/scala-package/examples/pom.xml
@@ -129,11 +129,5 @@
       <artifactId>slf4j-simple</artifactId>
       <version>1.7.5</version>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.11</version>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
 </project>
diff --git a/scala-package/infer/pom.xml b/scala-package/infer/pom.xml
index 13ceebb83cd9..565ac6e393a5 100644
--- a/scala-package/infer/pom.xml
+++ b/scala-package/infer/pom.xml
@@ -64,13 +64,5 @@
       <version>1.10.19</version>
       <scope>test</scope>
     </dependency>
-
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.11</version>
-      <scope>test</scope>
-    </dependency>
-
   </dependencies>
 </project>
diff --git a/scala-package/pom.xml b/scala-package/pom.xml
index 07baeab9b63f..5ba6f1f9f498 100644
--- a/scala-package/pom.xml
+++ b/scala-package/pom.xml
@@ -412,6 +412,12 @@
       <version>1.13.5</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.11</version>
+      <scope>test</scope>
+    </dependency>
 
     <!-- Following libraries are required by running javah, they should be excluded from .jar -->
     <dependency>

From f1dcf99d0083e6e8904548651d43d7d76d299a9c Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Wed, 16 Jan 2019 11:58:51 -0800
Subject: [PATCH 10/11] update documentation

---
 .../core/src/main/scala/org/apache/mxnet/Image.scala        | 6 +++---
 .../src/main/scala/org/apache/mxnet/javaapi/Image.scala     | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala
index 473cb7c1ae91..0f756e24027f 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/Image.scala
@@ -37,7 +37,7 @@ object Image {
     * @param flag   Convert decoded image to grayscale (0) or color (1).
     * @param to_rgb Whether to convert decoded image
     *               to mxnet's default RGB format (instead of opencv's default BGR).
-    * @return NDArray in HWC format with DType uint8
+    * @return NDArray in HWC format with DType [[DType.UInt8]]
     */
   def imDecode(buf: Array[Byte], flag: Int,
                to_rgb: Boolean,
@@ -56,7 +56,7 @@ object Image {
   /**
     * Same imageDecode with InputStream
     * @param inputStream the inputStream of the image
-    * @return NDArray in HWC format with DType uint8
+    * @return NDArray in HWC format with DType [[DType.UInt8]]
     */
   def imDecode(inputStream: InputStream, flag: Int = 1,
                to_rgb: Boolean = true,
@@ -78,7 +78,7 @@ object Image {
     * @param flag     Convert decoded image to grayscale (0) or color (1).
     * @param to_rgb   Whether to convert decoded image to mxnet's default RGB format
     *                 (instead of opencv's default BGR).
-    * @return org.apache.mxnet.NDArray in HWC format with DType uint8
+    * @return org.apache.mxnet.NDArray in HWC format with DType [[DType.UInt8]]
     */
   def imRead(filename: String, flag: Option[Int] = None,
              to_rgb: Option[Boolean] = None,
diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
index 531d0b1f96fa..c469b01b7ea5 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
@@ -29,7 +29,7 @@ object Image {
     * @param flag   Convert decoded image to grayscale (0) or color (1).
     * @param toRGB Whether to convert decoded image
     *               to mxnet's default RGB format (instead of opencv's default BGR).
-    * @return NDArray in HWC format with DType uint8
+    * @return NDArray in HWC format with DType [[DType.UInt8]]
     */
   def imDecode(buf: Array[Byte], flag: Int, toRGB: Boolean): NDArray = {
     org.apache.mxnet.Image.imDecode(buf, flag, toRGB, None)
@@ -38,7 +38,7 @@ object Image {
   /**
     * Same imageDecode with InputStream
     * @param inputStream the inputStream of the image
-    * @return NDArray in HWC format with DType uint8
+    * @return NDArray in HWC format with DType [[DType.UInt8]]
     */
   def imDecode(inputStream: InputStream, flag: Int = 1, toRGB: Boolean = true): NDArray = {
     org.apache.mxnet.Image.imDecode(inputStream, flag, toRGB, None)
@@ -51,7 +51,7 @@ object Image {
     * @param flag     Convert decoded image to grayscale (0) or color (1).
     * @param toRGB   Whether to convert decoded image to mxnet's default RGB format
     *                 (instead of opencv's default BGR).
-    * @return org.apache.mxnet.NDArray in HWC format with DType uint8
+    * @return org.apache.mxnet.NDArray in HWC format with DType [[DType.UInt8]]
     */
   def imRead(filename: String, flag: Int, toRGB: Boolean = true): NDArray = {
     org.apache.mxnet.Image.imRead(filename, Some(flag), Some(toRGB), None)

From 0f6e376bc5c1c0db7f4547cd759fd0e396790e15 Mon Sep 17 00:00:00 2001
From: Qing <lanking520@live.com>
Date: Wed, 30 Jan 2019 13:25:24 -0800
Subject: [PATCH 11/11] add simplified methods

---
 .../org/apache/mxnet/javaapi/Image.scala      | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
index c469b01b7ea5..7d6f31e930ad 100644
--- a/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
+++ b/scala-package/core/src/main/scala/org/apache/mxnet/javaapi/Image.scala
@@ -35,15 +35,26 @@ object Image {
     org.apache.mxnet.Image.imDecode(buf, flag, toRGB, None)
   }
 
+  def imDecode(buf: Array[Byte]): NDArray = {
+    imDecode(buf, 1, true)
+  }
+
   /**
     * Same imageDecode with InputStream
+    *
     * @param inputStream the inputStream of the image
+    * @param flag   Convert decoded image to grayscale (0) or color (1).
+    * @param toRGB Whether to convert decoded image
     * @return NDArray in HWC format with DType [[DType.UInt8]]
     */
-  def imDecode(inputStream: InputStream, flag: Int = 1, toRGB: Boolean = true): NDArray = {
+  def imDecode(inputStream: InputStream, flag: Int, toRGB: Boolean): NDArray = {
     org.apache.mxnet.Image.imDecode(inputStream, flag, toRGB, None)
   }
 
+  def imDecode(inputStream: InputStream): NDArray = {
+    imDecode(inputStream, 1, true)
+  }
+
   /**
     * Read and decode image with OpenCV.
     * Note: return image in RGB by default, instead of OpenCV's default BGR.
@@ -53,10 +64,14 @@ object Image {
     *                 (instead of opencv's default BGR).
     * @return org.apache.mxnet.NDArray in HWC format with DType [[DType.UInt8]]
     */
-  def imRead(filename: String, flag: Int, toRGB: Boolean = true): NDArray = {
+  def imRead(filename: String, flag: Int, toRGB: Boolean): NDArray = {
     org.apache.mxnet.Image.imRead(filename, Some(flag), Some(toRGB), None)
   }
 
+  def imRead(filename: String): NDArray = {
+    imRead(filename, 1, true)
+  }
+
   /**
     * Resize image with OpenCV.
     * @param src     source image in NDArray
@@ -70,6 +85,10 @@ object Image {
     org.apache.mxnet.Image.imResize(src, w, h, interpVal, None)
   }
 
+  def imResize(src: NDArray, w: Int, h: Int): NDArray = {
+    imResize(src, w, h, null)
+  }
+
   /**
     * Do a fixed crop on the image
     * @param src Src image in NDArray