detect if bitmap is dark or light (android)

    public static boolean isDark(Bitmap bitmap) {
        final float darkThreshold = bitmap.getWidth() * bitmap.getHeight() * 0.45f;
        final int w = bitmap.getWidth();
        final int h = bitmap.getHeight();

        int darkPixels = 0;
        int[] lineColor = new int[w];
        for (int i = 0; i < h - 1; i++) {
            bitmap.getPixels(lineColor, 0, w, 0, i, w, 1);
            for (int color : lineColor) {
                final int r = Color.red(color);
                final int g = Color.green(color);
                final int b = Color.blue(color);
                final float luminance = (0.299f * r + 0.0f + 0.587f * g + 0.0f + 0.114f * b + 0.0f);
                if (luminance < 150) {
                    darkPixels++;
                }
            }
        }

        return darkPixels >= darkThreshold;
    }