Get RGB from a SurfaceView displaying Live camera

Question

I am displaying a live camera in SurfaceView using camera.startPreview();. Any idea on how I can get live RGB readings from the camera?

Thanks

Answer 1

I thought I could get the data converted from the SurfaceView. But the best method to use is :

• Set the camera's orientation to 90 degrees.
• Set output format to NV21 (which is guranteed to be supported on all devices).
• Set to turn the Flash ON.
• Start preview in the SurfaceView.

List item

camera = Camera.open();
cameraParam = camera.getParameters();
cameraParam.setPreviewFormat(ImageFormat.NV21);
camera.setDisplayOrientation(90);
camera.setParameters(cameraParam);
cameraParam = camera.getParameters();
camera.setPreviewDisplay(surfaceHolder);
cameraParam.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(cameraParam);
camera.startPreview();

Then, I call the setPreviewCallback and onPreviewFrame to get the incoming frame, and convert it to RGB pixel array. Which I can then get intensity of each color in the picture by averaging all pixels intensity by running myPixels array through a for loop, and checking Color.red(myPixels[i]) for each desired color (inside the onPreviewFrame).

camera.setPreviewCallback(new PreviewCallback() {
    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        int frameHeight = camera.getParameters().getPreviewSize().height;
        int frameWidth = camera.getParameters().getPreviewSize().width;
        // number of pixels//transforms NV21 pixel data into RGB pixels  
        int rgb[] = new int[frameWidth * frameHeight];
        // convertion
        int[] myPixels = decodeYUV420SP(rgb, data, frameWidth, frameHeight);
    }
}

Where decodeYUV420SP is found here.

I timed this operation to take about 200ms for each frame. Is there a faster way of doing it?