C＃：水印圖像質量差，保存JPEG時

我試圖在圖像上添加水印並將其保存爲最佳質量，但是當保存JPEG水印質量差（但主圖像質量好）時。C＃：水印圖像質量差，保存JPEG時

string wtrSrc = @"D:\watermark.png"; 
string imgSrc = @"D:\image.jpg"; 
string imgOutJPG = @"D:\result.jpg";   
string imgOutPNG = @"D:\result.png"; 

// create new image 
Bitmap imgOutput = new Bitmap(imgSrc); 
Graphics outputGraphics = Graphics.FromImage(imgOutput); 

// image quality 
outputGraphics.CompositingQuality = CompositingQuality.HighQuality; 
outputGraphics.InterpolationMode = InterpolationMode.HighQualityBilinear; 
outputGraphics.SmoothingMode = SmoothingMode.HighQuality; 
outputGraphics.PixelOffsetMode = PixelOffsetMode.HighQuality; 

// create watermark image 
System.Drawing.Image wtrmark = System.Drawing.Image.FromFile(wtrSrc);   

// add waternark 
float wtrmarkX = 10; 
float wtrmarkY = 10; 
outputGraphics.DrawImage(wtrmark, wtrmarkX, wtrmarkY); 

//set jpeg quality  
EncoderParameters myEncoderParameters = new EncoderParameters(1); 
EncoderParameter myEncoderParameter = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L); 
myEncoderParameters.Param[0] = myEncoderParameter; 

// save result 
imgOutput.Save(imgOutJPG, GetEncoder(ImageFormat.Jpeg), myEncoderParameters); 
imgOutput.Save(imgOutPNG, ImageFormat.Png); 

// clean 
wtrmark.Dispose(); 
imgOutput.Dispose(); 
outputGraphics.Dispose();

......

// ImageCodecInfo 
    private ImageCodecInfo GetEncoder(ImageFormat format) 
    { 

     ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders(); 

     foreach (ImageCodecInfo codec in codecs) 
     { 
      if (codec.FormatID == format.Guid) 
      { 
       return codec; 
      } 
     } 
     return null; 
    }

PNG節能效果很好，但我需要保存JPEG。這裏的PNG和JPEG http://i.stack.imgur.com/CqwgZ.jpg

之間的區別我跟着這篇文章http://www.codeproject.com/Articles/2927/Creating-a-Watermarked-Photograph-with-GDI-for-NET並得到同樣的結果。

有沒有辦法讓JPEG上的水印看起來不錯？

來源

2013-05-03 user1032559

難道你的問題是源圖像如http在透明度：// stackoverflow.com/questions/6513633/c-convert-transparent-png-to-jpg-with-non-black-background-color？ – 2013-05-03 16:26:36

不，我試圖用作水印簡單的JPEG圖像，結果是一樣的。以下是示例 - http://i.imgur.com/SZQuEyR.jpg?1 – user1032559 2013-05-03 19:11:09

您是否嘗試過InterpolationMode.InterpolationModeHighQualityBicubic？ – 2013-05-05 19:25:43

首先intall ImageMagick的在C：\使用

http://www.imagemagick.org/download/binaries/ImageMagick-6.8.8-7-Q16-x86-dll.exe

在窗戶的ImageMagick文件夾而安裝添加C：\ ImageMagick的;在PATH變量enviornment

，並使用下面的代碼，我們B服務

using System.IO; 
    using System.Drawing; 

    [WebMethod] 
     public Byte[] WatermarkImage(Byte[] image) 
     { 
    MemoryStream ms = new MemoryStream(image); 
    Image image2 = Image.FromStream(ms); 
    image2.Save(Server.MapPath("~") + "\\imageTest.jpg"); 
    string strCmdText; 
    strCmdText = "/C convert.exe -draw \"gravity south fill black text 0,0 'Parth' \" \"" + Server.MapPath("~") +"\\imageTest.jpg \" \""+Server.MapPath("~") +"\\imageTest_result.jpg \""; 
    System.Diagnostics.Process.Start("CMD.exe", strCmdText); 
    System.Threading.Thread.Sleep(1000); 
    byte[] imgdata = System.IO.File.ReadAllBytes(Server.MapPath("~") +"\\imageTest_result.jpg"); 
    return imgdata; 
     }

在網頁中使用

 protected void Button1_Click(object sender, EventArgs e) 
     { 
      if (this.FileUpload1.HasFile) 
      { 
     if (FileUpload1.PostedFile.ContentType == "image/jpeg") 
     { 
      if (FileUpload1.PostedFile.ContentLength < 512000) 
      { 
       string filename = Path.GetFileName(FileUpload1.FileName); 
       FileUpload1.SaveAs(Server.MapPath("~") + "\\" + filename); 
       Watermark w = new Watermark(); 
       Byte[] b = w.WatermarkImage(GetBytesFromFile(Server.MapPath("~") + "\\" + filename)); 
       MemoryStream ms = new MemoryStream(b); 
       System.Drawing.Image image2 = System.Drawing.Image.FromStream(ms); 
       image2.Save(Server.MapPath("~") + "\\imageTest_op.jpg"); 
       Image1.ImageUrl = "imageTest_op.jpg"; 
      } 
       } 
      } 
     }

來源

2014-03-03 10:17:36

C＃：水印圖像質量差，保存JPEG時

回答

相關問題