To support Yolov8 (#2776)

---------

Co-authored-by: KexinFeng <fenkexin@amazon.com>

api/src/main/java/ai/djl/modality/cv/translator/YoloV5Translator.java

@@ -160,7 +160,7 @@ protected double overlap(double x1, double w1, double x2, double w2) {
         return right - left;
     }
 
-    private DetectedObjects processFromBoxOutput(NDList list) {
+    protected DetectedObjects processFromBoxOutput(NDList list) {
         float[] flattened = list.get(0).toFloatArray();
         ArrayList<IntermediateResult> intermediateResults = new ArrayList<>();
         int sizeClasses = classes.size();
@@ -280,7 +280,7 @@ public YoloV5Translator build() {
         }
     }
 
-    private static final class IntermediateResult {
+    protected static final class IntermediateResult {
 
         /**
          * A sortable score for how good the recognition is relative to others. Higher should be

api/src/main/java/ai/djl/modality/cv/translator/YoloV8Translator.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file 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 ai.djl.modality.cv.translator;
+
+import ai.djl.modality.cv.output.DetectedObjects;
+import ai.djl.modality.cv.output.Rectangle;
+import ai.djl.ndarray.NDArray;
+import ai.djl.ndarray.NDList;
+import ai.djl.ndarray.types.DataType;
+
+import java.util.ArrayList;
+import java.util.Map;
+
+/**
+ * A translator for YoloV8 models. This was tested with ONNX exported Yolo models. For details check
+ * here: https://github.com/ultralytics/ultralytics
+ */
+public class YoloV8Translator extends YoloV5Translator {
+
+    /**
+     * Constructs an ImageTranslator with the provided builder.
+     *
+     * @param builder the data to build with
+     */
+    protected YoloV8Translator(Builder builder) {
+        super(builder);
+    }
+
+    /**
+     * Creates a builder to build a {@code YoloV8Translator} with specified arguments.
+     *
+     * @param arguments arguments to specify builder options
+     * @return a new builder
+     */
+    public static YoloV8Translator.Builder builder(Map<String, ?> arguments) {
+        YoloV8Translator.Builder builder = new YoloV8Translator.Builder();
+        builder.configPreProcess(arguments);
+        builder.configPostProcess(arguments);
+
+        return builder;
+    }
+
+    @Override
+    protected DetectedObjects processFromBoxOutput(NDList list) {
+        NDArray features4OneImg = list.get(0);
+        int sizeClasses = classes.size();
+        long sizeBoxes = features4OneImg.size(1);
+        ArrayList<IntermediateResult> intermediateResults = new ArrayList<>();
+
+        for (long b = 0; b < sizeBoxes; b++) {
+            float maxClass = 0;
+            int maxIndex = 0;
+            for (int c = 4; c < sizeClasses; c++) {
+                float classProb = features4OneImg.getFloat(c, b);
+                if (classProb > maxClass) {
+                    maxClass = classProb;
+                    maxIndex = c;
+                }
+            }
+
+            if (maxClass > threshold) {
+                float xPos = features4OneImg.getFloat(0, b); // center x
+                float yPos = features4OneImg.getFloat(1, b); // center y
+                float w = features4OneImg.getFloat(2, b);
+                float h = features4OneImg.getFloat(3, b);
+                Rectangle rect =
+                        new Rectangle(Math.max(0, xPos - w / 2), Math.max(0, yPos - h / 2), w, h);
+                intermediateResults.add(
+                        new IntermediateResult(classes.get(maxIndex), maxClass, maxIndex, rect));
+            }
+        }
+
+        return nms(intermediateResults);
+    }
+
+    /** The builder for {@link YoloV8Translator}. */
+    public static class Builder extends YoloV5Translator.Builder {
+        /**
+         * Builds the translator.
+         *
+         * @return the new translator
+         */
+        @Override
+        public YoloV8Translator build() {
+            if (pipeline == null) {
+                addTransform(
+                        array -> array.transpose(2, 0, 1).toType(DataType.FLOAT32, false).div(255));
+            }
+            validate();
+            return new YoloV8Translator(this);
+        }
+    }
+}

api/src/main/java/ai/djl/modality/cv/translator/YoloV8TranslatorFactory.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file 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 ai.djl.modality.cv.translator;
+
+import ai.djl.Model;
+import ai.djl.modality.cv.Image;
+import ai.djl.modality.cv.output.DetectedObjects;
+import ai.djl.translate.Translator;
+
+import java.io.Serializable;
+import java.util.Map;
+
+/** A translatorFactory that creates a {@link YoloV8Translator} instance. */
+public class YoloV8TranslatorFactory extends ObjectDetectionTranslatorFactory
+        implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    /** {@inheritDoc} */
+    @Override
+    protected Translator<Image, DetectedObjects> buildBaseTranslator(
+            Model model, Map<String, ?> arguments) {
+        return YoloV8Translator.builder(arguments).build();
+    }
+}

api/src/test/java/ai/djl/modality/cv/translator/YoloV8TranslatorFactoryTest.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file 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 ai.djl.modality.cv.translator;
+
+import ai.djl.Model;
+import ai.djl.modality.Input;
+import ai.djl.modality.Output;
+import ai.djl.modality.cv.Image;
+import ai.djl.modality.cv.output.DetectedObjects;
+import ai.djl.translate.BasicTranslator;
+import ai.djl.translate.Translator;
+
+import org.testng.Assert;
+import org.testng.annotations.BeforeClass;
+import org.testng.annotations.Test;
+
+import java.io.InputStream;
+import java.net.URL;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+
+public class YoloV8TranslatorFactoryTest {
+
+    private YoloV8TranslatorFactory factory;
+
+    @BeforeClass
+    public void setUp() {
+        factory = new YoloV8TranslatorFactory();
+    }
+
+    @Test
+    public void testGetSupportedTypes() {
+        Assert.assertEquals(factory.getSupportedTypes().size(), 5);
+    }
+
+    @Test
+    public void testNewInstance() {
+        Map<String, String> arguments = new HashMap<>();
+        try (Model model = Model.newInstance("test")) {
+            Translator<Image, DetectedObjects> translator1 =
+                    factory.newInstance(Image.class, DetectedObjects.class, model, arguments);
+            Assert.assertTrue(translator1 instanceof YoloV8Translator);
+
+            Translator<Path, DetectedObjects> translator2 =
+                    factory.newInstance(Path.class, DetectedObjects.class, model, arguments);
+            Assert.assertTrue(translator2 instanceof BasicTranslator);
+
+            Translator<URL, DetectedObjects> translator3 =
+                    factory.newInstance(URL.class, DetectedObjects.class, model, arguments);
+            Assert.assertTrue(translator3 instanceof BasicTranslator);
+
+            Translator<InputStream, DetectedObjects> translator4 =
+                    factory.newInstance(InputStream.class, DetectedObjects.class, model, arguments);
+            Assert.assertTrue(translator4 instanceof BasicTranslator);
+
+            Translator<Input, Output> translator5 =
+                    factory.newInstance(Input.class, Output.class, model, arguments);
+            Assert.assertTrue(translator5 instanceof ImageServingTranslator);
+
+            Assert.assertThrows(
+                    IllegalArgumentException.class,
+                    () -> factory.newInstance(Image.class, Output.class, model, arguments));
+        }
+    }
+}

examples/src/main/java/ai/djl/examples/inference/Yolov8Detection.java

@@ -0,0 +1,132 @@
+/*
+ * Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file 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 ai.djl.examples.inference;
+
+import ai.djl.ModelException;
+import ai.djl.inference.Predictor;
+import ai.djl.modality.cv.Image;
+import ai.djl.modality.cv.ImageFactory;
+import ai.djl.modality.cv.output.BoundingBox;
+import ai.djl.modality.cv.output.DetectedObjects;
+import ai.djl.modality.cv.output.DetectedObjects.DetectedObject;
+import ai.djl.modality.cv.output.Rectangle;
+import ai.djl.modality.cv.translator.YoloV8TranslatorFactory;
+import ai.djl.repository.zoo.Criteria;
+import ai.djl.repository.zoo.ZooModel;
+import ai.djl.training.util.ProgressBar;
+import ai.djl.translate.TranslateException;
+import ai.djl.translate.Translator;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/** An example of inference using an yolov8 model. */
+public final class Yolov8Detection {
+
+    private static final Logger logger = LoggerFactory.getLogger(Yolov8Detection.class);
+
+    private Yolov8Detection() {}
+
+    public static void main(String[] args) throws IOException, ModelException, TranslateException {
+        DetectedObjects detection = Yolov8Detection.predict();
+        logger.info("{}", detection);
+    }
+
+    public static DetectedObjects predict() throws IOException, ModelException, TranslateException {
+        String classPath = System.getProperty("java.class.path");
+        String pathSeparator = System.getProperty("path.separator");
+        classPath = classPath.split(pathSeparator)[0];
+        Path modelPath = Paths.get(classPath + "/yolov8n.onnx");
+        Path imgPath = Paths.get(classPath + "/yolov8_test.jpg");
+        Image img = ImageFactory.getInstance().fromFile(imgPath);
+
+        Map<String, Object> arguments = new ConcurrentHashMap<>();
+        arguments.put("width", 640);
+        arguments.put("height", 640);
+        arguments.put("resize", "true");
+        arguments.put("toTensor", true);
+        arguments.put("applyRatio", true);
+        arguments.put("threshold", 0.6f);
+        arguments.put("synsetFileName", "yolov8_synset.txt");
+
+        YoloV8TranslatorFactory yoloV8TranslatorFactory = new YoloV8TranslatorFactory();
+        Translator<Image, DetectedObjects> translator =
+                yoloV8TranslatorFactory.newInstance(
+                        Image.class, DetectedObjects.class, null, arguments);
+
+        Criteria<Image, DetectedObjects> criteria =
+                Criteria.builder()
+                        .setTypes(Image.class, DetectedObjects.class)
+                        .optModelPath(modelPath)
+                        .optEngine("OnnxRuntime")
+                        .optTranslator(translator)
+                        .optProgress(new ProgressBar())
+                        .build();
+
+        DetectedObjects detectedObjects;
+        DetectedObject detectedObject;
+        try (ZooModel<Image, DetectedObjects> model = criteria.loadModel();
+                Predictor<Image, DetectedObjects> predictor = model.newPredictor()) {
+            Path outputPath = Paths.get(classPath + "/output");
+            Files.createDirectories(outputPath);
+
+            detectedObjects = predictor.predict(img);
+
+            if (detectedObjects.getNumberOfObjects() > 0) {
+                List<DetectedObject> detectedObjectList = detectedObjects.items();
+                for (DetectedObject object : detectedObjectList) {
+                    detectedObject = object;
+                    BoundingBox boundingBox = detectedObject.getBoundingBox();
+                    Rectangle tectangle = boundingBox.getBounds();
+                    logger.info(
+                            detectedObject.getClassName()
+                                    + " "
+                                    + detectedObject.getProbability()
+                                    + " "
+                                    + tectangle.getX()
+                                    + " "
+                                    + tectangle.getY()
+                                    + " "
+                                    + tectangle.getWidth()
+                                    + " "
+                                    + tectangle.getHeight());
+                }
+
+                saveBoundingBoxImage(
+                        img.resize(640, 640, false),
+                        detectedObjects,
+                        outputPath,
+                        imgPath.toFile().getName());
+            }
+
+            return detectedObjects;
+        }
+    }
+
+    private static void saveBoundingBoxImage(
+            Image img, DetectedObjects detectedObjects, Path outputPath, String outputFileName)
+            throws IOException {
+        img.drawBoundingBoxes(detectedObjects);
+
+        Path imagePath = outputPath.resolve(outputFileName);
+        img.save(Files.newOutputStream(imagePath), "png");
+    }
+}