图片裁剪后图片大小变大

https://docs.microsoft.com/zh-cn/dotnet/api/system.drawing.imaging.encoder.quality?view=netframework-4.8

 public ActionResult SaveVideoThumbnailFile(string keyValue,string strEntity)
        {


            Encoder myEncoder;
            EncoderParameter myEncoderParameter;
            EncoderParameters myEncoderParameters;
            ImageCodecInfo myImageCodecInfo;
            myEncoder = Encoder.Quality;
            myEncoderParameters = new EncoderParameters(1);
            myEncoderParameter = new EncoderParameter(myEncoder, 100L);
            myEncoderParameters.Param[0] = myEncoderParameter;
            //int width= int height, int offsetX, int offsetY
          
            var PostData = strEntity.ToJObject();
            int width = (int)PostData["width"];
            int height = (int)PostData["height"];
            int offsetX = (int)PostData["offsetX"];
            int offsetY = (int)PostData["offsetY"];
            string filePath = "/Resource/VideoThumbnailFile/" + keyValue;
            //创建路径
string firstfile = System.Web.HttpContext.Current.Server.MapPath("~" + ModelList[0].VideoUrl);
                myImageCodecInfo = GetEncoderInfo(MimeMapping.GetMimeMapping(firstfile));
                yfile = System.Web.HttpContext.Current.Server.MapPath("~" + model.VideoUrl);
                file = yfile.Replace("VideoFile", "VideoThumbnailFile");
                Bitmap refile = GetPartOfImageRec(yfile, width, height, offsetX, offsetY);
                refile.Save(file,myImageCodecInfo, myEncoderParameters);
            
 
        }

 /// <summary>
        /// 截取一张图片的指定部分
        /// </summary>
        /// <param name="bitmapPathAndName">原始图片路径名称</param>
        /// <param name="width">截取图片的宽度</param>
        /// <param name="height">截取图片的高度</param>
        /// <param name="offsetX">开始截取图片的X坐标</param>
        /// <param name="offsetY">开始截取图片的Y坐标</param>
        /// <returns></returns>
        public  Bitmap GetPartOfImageRec(string bitmapPathAndName, int width, int height, int offsetX, int offsetY)
        {
            Bitmap sourceBitmap = new Bitmap(bitmapPathAndName);
            Bitmap resultBitmap = new Bitmap(width, height);
            using (Graphics g = Graphics.FromImage(resultBitmap))
            {
                Rectangle resultRectangle = new Rectangle(0, 0, width, height);
                Rectangle sourceRectangle = new Rectangle(0 + offsetX, 0 + offsetY, width, height);
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                g.Clear(Color.White);
                g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel);
            }
            return resultBitmap;
        }

/// <summary>       
/// 截取一张图片的指定部分        
/// </summary>        
/// <param name="bitmapPathAndName">原始图片路径名称</param>        
/// <param name="width">截取图片的宽度</param>        
/// <param name="height">截取图片的高度</param>        
/// <param name="offsetX">开始截取图片的X坐标</param>        
/// <param name="offsetY">开始截取图片的Y坐标</param>        
/// <returns></returns>        
public  Bitmap GetPartOfImageRec(string bitmapPathAndName, int width, int height, int offsetX, int offsetY)        
{            
    Bitmap sourceBitmap = new Bitmap(bitmapPathAndName);            
    Bitmap resultBitmap = new Bitmap(width, height);           
     using (Graphics g = Graphics.FromImage(resultBitmap))            
        {                
            Rectangle resultRectangle = new Rectangle(0, 0, width, height);                
            Rectangle sourceRectangle = new Rectangle(0 + offsetX, 0 + offsetY, width, height);                
             g.InterpolationMode =System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;                
             g.SmoothingMode =System.Drawing.Drawing2D.SmoothingMode.HighQuality;                
             g.Clear(Color.White);                
             g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel);            
        }           
     return resultBitmap;       
}            