Convert base64 png image to base64 jpg image without saving

private byte[] Base64Png2Jpeg(string base64)
{
    byte[] jpgArray;
    Byte[] pngBytes = Convert.FromBase64String(base64);

    using (MemoryStream msPng = new MemoryStream(pngBytes))
    {
        using (Image  img = Image.FromStream(msPng))
        {
            using (MemoryStream msJpeg = new MemoryStream())
            {
                img.Save(msJpeg, ImageFormat.Jpeg);
                jpgArray = msJpeg.ToArray();
            }
        }
    }
    return (jpgArray);
}

private string FromBase64PNGToBase64JPG(string base64PNG)
    {
    byte[] bytes = Convert.FromBase64String(base64PNG);
    using (MemoryStream msIn = new MemoryStream(bytes))
        {
        using (Image pic = Image.FromStream(msIn))
            {
            using (MemoryStream msOut = new MemoryStream())
                {
                pic.Save(msOut, System.Drawing.Imaging.ImageFormat.Jpeg);
                return Convert.ToBase64String(msOut.ToArray());
                }
            }
        }
    }