无法从带有索引像素格式的图像创建graphics对象

/// <summary>
/// 会产生graphics异常的PixelFormat
/// </summary>
private static PixelFormat[] indexedPixelFormats = { PixelFormat.Undefined, PixelFormat.DontCare,
PixelFormat.Format16bppArgb1555, PixelFormat.Format1bppIndexed, PixelFormat.Format4bppIndexed,
PixelFormat.Format8bppIndexed
    };

/// <summary>
/// 判断图片的PixelFormat 是否在 引发异常的 PixelFormat 之中
/// </summary>
/// <param name="imgPixelFormat">原图片的PixelFormat</param>
/// <returns></returns>
private static bool IsPixelFormatIndexed(PixelFormat imgPixelFormat)
{
    foreach (PixelFormat pf in indexedPixelFormats)
    {
        if (pf.Equals(imgPixelFormat)) return true;
    }

    return false;
}

 if (IsPixelFormatIndexed(sBitmap.PixelFormat))
            {
                Bitmap bmp = new Bitmap(sBitmap.Width, sBitmap.Height, PixelFormat.Format32bppArgb);
                using (Graphics g = Graphics.FromImage(bmp))
                {
                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                    g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                    g.DrawImage(sBitmap, 0, 0);
                }
                sBitmap = bmp;
            }
            Graphics graphics = Graphics.FromImage(sBitmap);