Add OpenCV README

docs/mkdocs.yml

@@ -131,8 +131,9 @@ nav:
   - Extensions:
       - Android: 'android/README.md'
       - AWS S3 support: 'extensions/aws-ai/README.md'
-      - Hadoop support: 'extensions/hadoop/README.md'
       - fastText: 'extensions/fasttext/README.md'
+      - Hadoop support: 'extensions/hadoop/README.md'
+      - OpenCV: 'extensions/opencv/README.md'
       - SentencePiece: 'extensions/sentencepiece/README.md'
   - Demos:
       - Demos: 'docs/demos/README.md'

extensions/opencv/README.md

@@ -0,0 +1,26 @@
+# Image support with OpenCV
+
+This module contains the image support extension with [OpenCV](https://opencv.org/). It is based on the [Java package from OpenPnP](https://github.com/openpnp/opencv).
+
+Right now, the package provides an `OpenCVImage` that acts as a faster implementation than the native `BufferedImage`. Once this package is added to your classpath, it will automatically be used through the standard DJL `ImageFactory`.
+
+## Documentation
+
+You can build the latest javadocs locally using the following command:
+
+```sh
+./gradlew javadoc
+```
+The javadocs output is built in the `build/doc/javadoc` folder.
+
+## Installation
+
+You can pull the module from the central Maven repository by including the following dependency in your `pom.xml` file:
+
+```xml
+<dependency>
+    <groupId>ai.djl.opencv</groupId>
+    <artifactId>opencv</artifactId>
+    <version>0.14.0</version>
+</dependency>
+```

extensions/opencv/src/main/java/ai/djl/opencv/OpenCVImageFactory.java

@@ -83,8 +83,8 @@ public Image fromNDArray(NDArray array) {
             array = array.transpose(1, 2, 0);
             shape = array.getShape();
         }
-        int width = (int) shape.get(1);
-        int height = (int) shape.get(0);
+        int width = Math.toIntExact(shape.get(1));
+        int height = Math.toIntExact(shape.get(0));
         Mat img = new Mat(height, width, CvType.CV_8UC3);
         img.put(0, 0, array.toByteArray());
         Imgproc.cvtColor(img, img, Imgproc.COLOR_RGB2BGR);