JavaCV-提高网络摄像头质量

Question

im currently trying to implement a webcam scanner. My current problem is that i can't capture a high quality image when using Java. The camera i use has 8MP and produces great images when i use the Windows "Camera"-App. Sadly i can't replicate this quality with JavaCV.

This is the (important) code i'm using to capture an Image:

FrameGrabber grabber;
private Java2DFrameConverter frameConverter;
public JavaCVCamera(String imagePath, double rotation) {
    this.frameConverter = new Java2DFrameConverter();
    this.imagePath = imagePath;
    this.rotation = rotation;
    this.grabber = new OpenCVFrameGrabber(0);
    this.grabber.setImageWidth(3264);
    this.grabber.setImageHeight(2448);
    try {
        this.grabber.start();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
public void saveImageToFile(boolean applyUpscaling, boolean applyRotation) {
    File folder = new File(imagePath);
    if (!folder.exists()) {
        folder.mkdirs();
    }

    try {
        BufferedImage img = frameConverter.convert(grabber.grab());

        if (applyUpscaling) {
            img = Thumbnails.of(img).forceSize(3264, 2448).asBufferedImage();
        }

        if (applyRotation) {
            img = rotateImageByDegrees(img, rotation);
        }

        File path = new File(imagePath + "/img_"
                + LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy_MM_dd_HH_mm_ss")) + "." + "png");
        ImageIO.write(img, "png", path);
        LOGGER.info("Captured Image: {}", path.toString());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

(Note: i dont use upscaling to make the images larger)

For your understanding, here's an example:

• Captured with Windows Camera App
• https://imgur.com/a/oOuMJdl
• Captured with Java+JavaCV
• https://imgur.com/a/DghFT8z

Is there some way to capture images with the same resolution and quality as the Windows Camera App?

Kind Regards, QUE

Answer 1

A BufferedImage is very memory consuming in Java as it stores the image in a Bitmap like image format. Other image formats that use compression consume less memory. But how to use them with JavaCV?

First of all, check with a profiler app which code is responsible for the extensive memory consumption of your implementation. Hopefully the Frame stores the image data still in compressed form; and when executing the frameConverter.convert it consumes the high ammount of memory. In this case, search for a solution that stores the image as a JPEG (or any other compressed data) in a byte[] - for displaying the image, you can draw the image directly eg to a Graphics2D element w/o converting it to a BufferedImage first. Use ToolkitImage therefore, which is able to draw a JPEG image from an InputStream image source. This can be a ByteArrayInputStream, if you were able to store your high-res image in a JPEG directly from the JavaCV.