WVGA icon size : 72x72                    HVGA icon size : 48x48              QVGA icon size : 36x36
Pixel : 480 x 800                              Pixel : 320 x 480                       Pixel : 240 x 320
3.7in                                             3.2in                                      2.7in
densityDpi : 240                               densityDpi : 160                       densityDpi : 120

px을 dp로 변환한다면 dp = px * 0.66625로 계산한다.(해상도480*800 기준)

DisplayMetrics displayMetrics = new DisplayMetrics();

((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);

WidthPixel = displayMetrics.widthPixels;

HeightPixel = displayMetrics.heightPixels;

pixel = dp * displayMetrics .density;