How to take a Bitmap (in RGB) and grab the luminance values for YUV. Useful for passing an image to ZXing for processing.

populateYUVLuminanceFromRGB.java

public void handleBitmap(Bitmap image) {
	int w = image.getWidth(), h = image.getHeight();
	int[] rgb = new int[w * h];
	byte[] yuv = new byte[w * h];

	image.getPixels(rgb, 0, w, 0, 0, w, h);
	populateYUVLuminanceFromRGB(rgb, yuv, w, h);
}

// Inspired in large part by:
// http://ketai.googlecode.com/svn/trunk/ketai/src/edu/uic/ketai/inputService/KetaiCamera.java
private void populateYUVLuminanceFromRGB(int[] rgb, byte[] yuv420sp, int width, int height) {
	for (int i = 0; i < width * height; i++) {
		float red = (rgb[i] >> 16) & 0xff;
		float green = (rgb[i] >> 8) & 0xff;
		float blue = (rgb[i]) & 0xff;
		int luminance = (int) ((0.257f * red) + (0.504f * green) + (0.098f * blue) + 16);
		yuv420sp[i] = (byte) (0xff & luminance);
	}
}