Camera image processing in Java

**stud91** · 04-14-2012, 01:28 PM

Basically I have a camera chip (Camera module: C3038, uses OmniVision’s CMOS image sensor OV6630) connected to a PC through a RS232 link. I want to read image data in a Java program which is in this format (according to camera specification):

My implementation is as follows...However the program doesn't proceed to the GUI stage after the whole image is transferred to the PC from the camera chip...i.e. the while loop at line 58 doesn't break...

Java Code:

public class SimpleRead implements Runnable, SerialPortEventListener {
static CommPortIdentifier portId;
static Enumeration portList;

InputStream inputStream;
SerialPort serialPort;
Thread readThread;
byte [] readBuffer;
static byte [] storeBuffer;

public SimpleRead() {
    try {
        serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);
    } catch (PortInUseException e) {System.out.println(e);}
    try {
        inputStream = serialPort.getInputStream();
    } catch (IOException e) {System.out.println(e);}
try {
        serialPort.addEventListener(this);
} catch (TooManyListenersException e) {System.out.println(e);}
    serialPort.notifyOnDataAvailable(true);
    try {
        serialPort.setSerialPortParams(9600,
            SerialPort.DATABITS_8,
            SerialPort.STOPBITS_1,
            SerialPort.PARITY_NONE);
    } catch (UnsupportedCommOperationException e) {System.out.println(e);}
    readThread = new Thread(this);
    readThread.start();
}

public void run() {
    try {
        Thread.sleep(20000);
    } catch (InterruptedException e) {System.out.println(e);}
}
@Override
public void serialEvent(SerialPortEvent event){
    switch(event.getEventType()) {
    case SerialPortEvent.BI:
    case SerialPortEvent.OE:
    case SerialPortEvent.FE:
    case SerialPortEvent.PE:
    case SerialPortEvent.CD:
    case SerialPortEvent.CTS:
    case SerialPortEvent.DSR:
    case SerialPortEvent.RI:
    case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
        break;
    case SerialPortEvent.DATA_AVAILABLE:
        readBuffer = new byte[20];
        ByteArrayOutputStream bias = new ByteArrayOutputStream();

        String a = new String();
        String b = new String();

        try {
            while (inputStream.available() > 0) {
                b += readBuffer;
                int numBytes = inputStream.read(readBuffer);
                a += readBuffer;
                System.out.print(new String(readBuffer));
                storeBuffer = new byte[numBytes];
                inputStream.read(storeBuffer);

                if(b.equals(a)){// to indicate end of image
                    break;
                }
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        InputStream in = new ByteArrayInputStream(storeBuffer);
        BufferedImage image = null;

        try {
            image = ImageIO.read(in);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //GUI for displaying image
        ImageIcon imageIcon = new ImageIcon(image);
        JLabel label = new JLabel();
        label.setIcon(imageIcon);
        JFrame frame = new JFrame("image display");
        frame.getContentPane().add(label,BorderLayout.CENTER);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);                       
        break;
    }
}

public static void main(String[] args) throws Exception {
    portList = CommPortIdentifier.getPortIdentifiers();

    while (portList.hasMoreElements()) {
        portId = (CommPortIdentifier) portList.nextElement();
        if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
             if (portId.getName().equals("COM7")) {
        //                if (portId.getName().equals("/dev/term/a")) {
                SimpleRead reader = new SimpleRead();
           }
        }
    }
}

**DarrylBurke** · 04-14-2012, 02:24 PM

You have two reads, on line 60 and 64. That's going to read twice, not read the same bytes twice.

db

**DarrylBurke** · 04-14-2012, 02:30 PM

Also note that it's woefully inefficient to (1) use a String assignment to a newly constructed empty String -- just assign to the empty String literal

Java Code:

String a = ""; // new String();

and (2) to use Strings at all when repeated concatenation is the order of the day. Use a StringBuilder / StringBuffer instead.

It also looks like you want to process binary data, so adding the data to a String isn't going to help. And this

Java Code:

InputStream in = new ByteArrayInputStream(storeBuffer);

gets only the data of the last read (i.e. the data read by the second read the last time through the loop) which certainly isn't going to give you all the bytes of the image.

I want to read image data in a Java program which is in this format (according to camera specification)

What format?

db

**DarrylBurke** · 04-14-2012, 02:39 PM

Looks like this is where the original code came from:
http://java.sun.com/developer/releas...impleRead.java

You might do better to make less changes in the original code, except for adding e.printStackTrace() in the empty catch block (very bad of Sun/Oracle to publish empty catch blocks at all). And instead of constructing a String from the bytes, you would probably want to aggregate and return the byte array read.

AFAIK javax.comm is less maintained than RXTX (google it) but I could be wrong.

db