Comparing two images to see if they are the same

/// <summary>
/// This method deals with checking whether the two bitmaps that are passed to it are the same or not
/// </summary>
/// <param name="img1">The first image</param>
/// <param name="img2">The second image</param>
/// <returns>True if the images are the same, else false</returns>
public static bool imagesAreTheSame(Bitmap img1, Bitmap img2)
{
    int imgHeight = img1.Height;
    int imgWidth = img1.Width;
    int hCounter = 0;
    int wCounter = 0;
    bool rtn = true;
    string pxl1;
    string pxl2;

    while (hCounter < imgHeight)
    {
        wCounter = 0;
        while (wCounter < imgWidth)
        {
            pxl1 = img1.GetPixel(hCounter, wCounter).ToString();
            pxl2 = img2.GetPixel(hCounter, wCounter).ToString();
            if (pxl1 != pxl2)
            {
                rtn = false;
                break;
            }
            wCounter += 1;
        }
        hCounter += 1;
        if (!rtn)
        {
            break;
        }
    }

    return rtn;
}