// The path to the documents directory.
String dataDir = "D:/WebPImages/";

String inputFile = dataDir + "Animation1.webp";
String outputFile = dataDir + "Animation2.webp";
try (ByteArrayOutputStream ms = new ByteArrayOutputStream())
{
    try (WebPImage image = (WebPImage)Image.load(inputFile))
    {
        image.resize(300, 450, ResizeType.HighQualityResample);
        image.crop(new Rectangle(10, 10, 200, 300));
        image.rotateFlipAll(RotateFlipType.Rotate90FlipX);
        image.save(ms);
    }

    try (FileOutputStream fs = new FileOutputStream(outputFile))
    {
        byte[] bytes = ms.toByteArray();
        fs.write(bytes, 0, bytes.length);
    }
}