在C＃中将Jpeg图像保存为更大的db

Question

我将图像保存到数据库，同时保持100％的质量。为了保持质量我使用以下方法。

public static byte[] ImageToByteArray(Image imageIn)
{
    var qualityParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
    var encoderParams = new EncoderParameters(1);
    encoderParams.Param[0] = qualityParam;
    using (var msStream = new MemoryStream())
    {
        imageIn.Save(msStream, GetEncoderInfo("image/png"), encoderParams);
        return msStream.ToArray();
    }
}

使用处理程序并使用以下方法从db I＆m 39中重新获取图像。

public void AddStampOnImage(Image img, HttpContext context)
{

    Image modiFiedImage = GetScaledImage(img, resizeWidth, resizeHeight);
    int width = modiFiedImage.Width;
    int height = modiFiedImage.Height;
    int compressionLevel = 100;

    Image bitmapImg = new Bitmap(width, height, modiFiedImage.PixelFormat);
    if (modiFiedImage.PixelFormat.ToString().Contains("Indexed"))
        bitmapImg = new Bitmap(width, height, PixelFormat.Format24bppRgb);


    PropertyItem[] propItems = img.PropertyItems;

    foreach (var item in propItems)
    {
        PropertyItem pItem = img.GetPropertyItem(item.Id);
        bitmapImg.SetPropertyItem(pItem);
    }

    Graphics oGraphic = Graphics.FromImage(bitmapImg);
    oGraphic.CompositingQuality = CompositingQuality.HighQuality;
    oGraphic.SmoothingMode = SmoothingMode.HighQuality;
    oGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
    oGraphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
    Rectangle oRectangle = new Rectangle(0, 0, width, height);
    oGraphic.DrawImage(modiFiedImage, oRectangle);

    int x;
    int y;
    Image watermarkImg = Image.FromFile(HttpContext.Current.Server.MapPath("~/images/" + watermarkimage + ""));
    GetWatermarkPlacement(oGraphic.DpiX, oGraphic.DpiY, width, height, watermarkImg, out x, out y);
    oGraphic.DrawImageUnscaled(watermarkImg, x, y);
    oGraphic.Dispose();
    watermarkImg.Dispose();

    long[] quality = new long[1];

    quality[0] = compressionLevel;

    EncoderParameters encoderParams = new EncoderParameters();
    EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
    encoderParams.Param[0] = encoderParam;

    ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
    ImageCodecInfo jpegICI = null;

    for (int i = 0; i < arrayICI.Length; i++)
    {
        if (arrayICI[i].FormatDescription.Equals("JPEG"))
        {
            jpegICI = arrayICI[i];
            break;
        }
    }

    SetImageCacheability(context);
    bitmapImg.Save(context.Response.OutputStream, jpegICI, encoderParams);

    encoderParam.Dispose();
}

这里的问题在某些情况下它工作正常意味着800kb图像可以在700-750kb中重新获得，但在某些情况下我保存了400kb图像并且它以800-1000kb图像重现。我不希望第二种情况发生。我在这里缺少什么？