Quality of a saved JPG in C#

Question

I made a small C# app to create an image in .jpg format.

pictureBox.Image.Save(name,ImageFormat.Jpeg);

The image is succesfully created. I input an original pic, do some stuff with it and save it. The quality of this new pic however, is lower than that of the original.

Is there any way to set the desired quality?

Answer 1

http://msdn.microsoft.com/en-us/library/system.drawing.imaging.encoderparameter.aspx

private void VaryQualityLevel()
{
    // Get a bitmap.
    Bitmap bmp1 = new Bitmap(@"c:\TestPhoto.jpg");
    ImageCodecInfo jgpEncoder = GetEncoder(ImageFormat.Jpeg);

    // Create an Encoder object based on the GUID
    // for the Quality parameter category.
    System.Drawing.Imaging.Encoder myEncoder =
        System.Drawing.Imaging.Encoder.Quality;

    // Create an EncoderParameters object.
    // An EncoderParameters object has an array of EncoderParameter
    // objects. In this case, there is only one
    // EncoderParameter object in the array.
    EncoderParameters myEncoderParameters = new EncoderParameters(1);

    EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, 
        50L);
    myEncoderParameters.Param[0] = myEncoderParameter;
    bmp1.Save(@"c:\TestPhotoQualityFifty.jpg", jgpEncoder, 
        myEncoderParameters);

    myEncoderParameter = new EncoderParameter(myEncoder, 100L);
    myEncoderParameters.Param[0] = myEncoderParameter;
    bmp1.Save(@"c:\TestPhotoQualityHundred.jpg", jgpEncoder, 
        myEncoderParameters);

    // Save the bitmap as a JPG file with zero quality level compression.
    myEncoderParameter = new EncoderParameter(myEncoder, 0L);
    myEncoderParameters.Param[0] = myEncoderParameter;
    bmp1.Save(@"c:\TestPhotoQualityZero.jpg", jgpEncoder, 
        myEncoderParameters);

}

Answer 2

Check out MSDN's article on how to set JPEG Compression level.

You need to use the other Save() overload that takes an ImageEncoder and its parameters.

Answer 3

See this article:

http://www.glennjones.net/Post/799/Highqualitydynamicallyresizedimageswithnet.htm