尝试保存图像时参数无效

Question

我在FileUtility类中使用此方法来保存图像。

public static void SaveImage(System.IO.Stream file, string savePath, Size size, bool enforceRatio, bool testReverse = false)
    {
        var image = Image.FromStream(file);
        var imageEncoders = ImageCodecInfo.GetImageEncoders();
        int enc = Path.GetExtension(savePath).ToLower().Contains("png") ? 4 : 1;
        EncoderParameters encoderParameters = new EncoderParameters(1);
        encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 90L);

        Size s = new Size(size.Width, size.Height);
        if (testReverse)
        {
            if (image.Width <= image.Height)
            {
                if (size.Width <= size.Height)
                {
                    s.Width = size.Width;
                    s.Height = size.Height;
                }
                else
                {
                    s.Width = size.Height;
                    s.Height = size.Width;
                }
            }
            else
            {
                if (size.Width <= size.Height)
                {
                    s.Width = size.Height;
                    s.Height = size.Width;
                }
                else
                {
                    s.Width = size.Width;
                    s.Height = size.Height;
                }
            }
        }

        var canvasWidth = s.Width;
        var canvasHeight = s.Height;
        var newImageWidth = s.Width;
        var newImageHeight = s.Height;
        var xPosition = 0;
        var yPosition = 0;
        if (enforceRatio)
        {
            var ratioX = s.Width / (double)image.Width;
            var ratioY = s.Height / (double)image.Height;
            var ratio = ratioX < ratioY ? ratioX : ratioY;
            newImageHeight = (int)(image.Height * ratio);
            newImageWidth = (int)(image.Width * ratio);
        }

        var thumbnail = new Bitmap(canvasWidth, canvasHeight);
        var graphic = Graphics.FromImage(thumbnail);

        if (enforceRatio)
        {
            graphic.Clear(Color.White);
        }

        graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
        graphic.SmoothingMode = SmoothingMode.HighQuality;
        graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
        graphic.CompositingQuality = CompositingQuality.HighQuality;
        graphic.DrawImage(image, xPosition, yPosition, newImageWidth, newImageHeight);

        thumbnail.Save(savePath, imageEncoders[enc], encoderParameters);
    }

效果很好。但是对于一些图像文件（不是每个文件），我得到了

  

参数异常：参数无效

在第一行var image = Image.FromStream(file);

我称这样的方法：

FileUtility.SaveImage(add2.IconSquare.InputStream, Server.MapPath(program.IconSquare), new System.Drawing.Size { Width = 250, Height = 250 }, false);

add2.IconSquare是一个HttpPostedFileBase

public HttpPostedFileBase IconSquare { get; set; }

唯一的事情是add2来自另一个使用TempData的动作。

var add2 = TempData["Create_Step2"] as AddStep2;

我的意思是我从Action Create_Step2中的用户获取文件并将它们保存在TempData中然后我尝试将它们保存在Action Create_Step3中。谁能告诉我我做错了什么？