camera getSnapshot not behaveing as planned

[strasni_betmen]

Hi all! First I want to thank in advance anyone who helps and say that I am aware that this is NOKIA forum.

I use SE K310, MIDP 2.0, CLDC 1.1.

My goal is to:
1.image1 = getSnapshot from camera
2.wait 200ms
3.image2 = getSnapshot from camera
4.process 2 previously captured images to see if they are different
5.if threy are different - exit the loop and draw the 2nd image - if not, continue to loop

Below is partial code I use, but sometimes it restarts the phone, sometimes goes very slowly.
I am not sure if I use the newly created thread correctly and wonder if something needs to be synchronized?! Or is this in general the right way to go about?!
How can I speed up things?

The CaptureCanvas is set on display externaly with:

                captureScreenCanvas.start();
                display.setCurrent(captureScreenCanvas);

Code below has been striped for null value checking and try-catch blocks.

public class CaptureScreen extends Canvas implements Runnable{

//...
//...various variable declarations and initializations, constructor...
//...

        public void start(){

                quit = false;
                initPlayer();

                Thread CaptureThread = new Thread(this,"DT");
                CaptureThread.start();

                setFullScreenMode(true);
        }

        public void run(){
                int[] Data1=null;
                int[] Data2=null;

                while(!quit){
                                capturedImage1 = captureImage();             //capture no.1
                                Data1 = makeData(capturedImage1);       //change 1st into array of integers(pixels)

                                Thread.sleep(300);

                                capturedImage2 = captureImage();             //capture no.2
                                Data2 = makeData(capturedImage2);       //change 2nd into array of integers(pixels)

                                quit = differentData(Data1,Data2);             //see if images are different
                }

                stop();
                repaint();
        }

        private Image captureImage() {
                byte[] imageData = null;
                Image img = null;

                imageData = vc.getSnapshot("encoding=jpeg&width=120&height=160");
                img = Image.createImage(imageData, 0, imageData.length);

                return img;
        }

        protected void paint(Graphics g){
                        if ((capturedImage2!=null) && quit){
                                g.drawImage(capturedImage2, 0, 0, 0);
                        }
        }

        public void initPlayer() {
                        playerVideo = Manager.createPlayer("capture://video?encoding=jpeg&width=120&height=160");
                        playerVideo.realize();
                        playerVideo.prefetch();
                        if ((vc = (VideoControl) playerVideo.getControl("VideoControl")) != null) {
                                vc.initDisplayMode(vc.USE_DIRECT_VIDEO, this);
                                vc.setDisplayLocation(0, 0);	
                                vc.setDisplayFullScreen(false);
                                vc.setDisplaySize(120, 60); 
                        }
                        playerVideo.start();
        }

        private int SingleColorThreshold = 15;
        private int Step = 10;
        private int ThresholdCount = 1000;

        // check if RED channel difference in every 10th(Step) pixel between 2 images is greater the SingleColorThreshold
       // if 2 pixels are recognized as different then increase the counter
       // run the for loop as long as counter is less than ThresholdCount

        public final synchronized  boolean differentData(int[] Data1, int[] Data2) throws IOException {
                count = 0;
                boolean temp = false;
                for (int i = 0; i < Data1.length; i += Step) {
                        if (java.lang.Math.abs(((Data2[i]>>16) & 0xff) - ((Data1[i] >> 16) & 0xff)) > SingleColorThreshold) {
                                count++;
                        }

                        if(count>ThresholdCount){
                                temp=true;
                                break;
                        }
                }
                return temp;
        }

        private int[] makeData(Image img) {

                int[] DataTemp = null;

                DataTemp = new int[img.getWidth() * img.getHeight()];
                img.getRGB(DataTemp, 0, img.getWidth(), 0, 0, img.getWidth(), img.getHeight());

                return DataTemp;
        }

        public void stop() {
                        vc = null;
                        playerVideo.stop();
                        playerVideo.close();
                        playerVideo = null;
                        playerSound.close();
                        playerSound = null;
        }
}

In short, all I want to do is capture images(in loop) on Sony Erricsson k310 and stop if they are different.
I havent figured it out what encodings are for setting gray capturing. I belive the device is capable of capturing in gray through j2me because there are options for gray capturing when using phones own camera software.

I would appreciate if anyone could help me with this or at least give me some pointers and information. Thank you!

[grahamhughes]

There is some sample code in the wiki...

Graham.