C#: Watermark image has poor quality when saving JPEG

Question

I'm trying to add watermark to image and save it at best quality, but when saving JPEG watermark has poor quality (but quality of main image is good).

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 saving works well, but I need to save JPEG. Here's the difference between PNG and JPEG https://i.stack.imgur.com/CqwgZ.jpg

I followed this article http://www.codeproject.com/Articles/2927/Creating-a-Watermarked-Photograph-with-GDI-for-NET and get the same result.

Is there a way to make watermark on JPEG looks good?

Could your problem be a transparency in the source image such as http://stackoverflow.com/questions/6513633/c-convert-transparent-png-to-jpg-with-non-black-background-color? — Bryan Roberts, May 03 '13 at 16:26
No, I tried to use as watermark simple JPEG image and result is the same. Here is example - http://i.imgur.com/SZQuEyR.jpg?1 — user1032559, May 03 '13 at 19:11
Have you tried InterpolationMode.InterpolationModeHighQualityBicubic ? — Matt Johnson, May 05 '13 at 19:25
I simplified the issue, but still with no result. Here the link - http://stackoverflow.com/questions/16373621/c-reduced-image-quality-when-saving-jpeg-at-100-quality — user1032559, May 06 '13 at 07:53
Your question is not about image watermarking but about plain image compression it seems. Your title is misleading. — , Oct 14 '15 at 11:20

score 1 · Accepted Answer · answered Mar 03 '14 at 10:17

First intall Imagemagick in C:\Imagemagick folder in windows using

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

while installation add C:\ImageMagick; in PATH enviornment variable

and use below code for we b service

    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;
        }

Use in your web page

      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";
            }
                 }
             }
         }

C#: Watermark image has poor quality when saving JPEG

1 Answers1