Detect dark image application: code that needs fixing

I need help with a simple app that checks the front camera for when the image goes dark. - suggest code provided - - The threshold value should be kept in a variable that i can change for testing. - Must have a method with the code to be executed when the threshold is reached (see example below - onPreviewFrame() ). For testing it should just show a popup with the current luminance value. - It should work with the lowest Android version possible (anything Gingerbread or higher hopefully ) That is it. I hope this is as simple as i think and welcome any suggestions regarding this posting. I found an example in Stackoverflow that might get it started: [login to view URL] ----- from stack overflow -------- This is fairly straightforward. You should use a surfaceview and camera preview. That way you get each frame as a byte array. The default format for the frame is YUV, which is Y (luminance) and UV, which are chrominance. You can use Y to calculate average luminance in the image. If you're using BGR, you can calculate luminance using: Y = 0.2126 R + 0.7152 G + 0.0722 B class Preview extends ViewGroup implements [login to view URL] { SurfaceView mSurfaceView; SurfaceHolder mHolder; Preview(Context context) { super(context); mSurfaceView = new SurfaceView(context); addView(mSurfaceView); // Install a [login to view URL] so we get notified when the // underlying surface is created and destroyed. mHolder = [login to view URL](); [login to view URL](this); [login to view URL](SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } ... } adding the callback to your class, means for every frame this method is called: onPreviewFrame(byte [] frame, Camera cam){ //do some processing // } --- end of stackoverflow -----