c# GDI+ Image.Save()或者Bitmap.Save()方法保存高质量图片

GDI+保存质量比较高的图片的方法，使用Image或者Bitmap的Save方法调节图像保存的质量。

 

Image.Save方法共有五种重 载 

其中Save(String, ImageCodecInfo, EncoderParameters)和Save(Stream, ImageCodecInfo,EncoderParameters)这两种方法课以调节图像质量。

 

Save.(string ,ImageCodeInfo,EncoderParameters) 使用方法：

参数：

filename                类型：System.String        字符串，包含要将此 Image 保存到的文件的名称。

encoder                 类型：System.Drawing.Imaging.ImageCodecInfo        此 Image 的 ImageCodecInfo。

encoderParams    类型：System.Drawing.Imaging.EncoderParameters            用于该 Image 的 EncoderParameters。

 

步骤：

①获得编码器的函数，

    ImageCodecInfo GetEncoderInfo(String mimeType)

    {
        int j; ImageCodecInfo[] encoders; encoders = ImageCodecInfo.GetImageEncoders(); for(j = 0; j < encoders.Length; ++j) { if(encoders[j].MimeType == mimeType) return encoders[j]; } return null; }

    可以直接复制过去使用。

②获取编码器

    ImageCodecInfo myImageCodecInfo;

    //获得JPEG格式的编码器

    myImageCodecInfo = GetEncoderInfo("image/jpeg");

③设置图像质量

    System.Drawing.Imaging.Encoder myEncoder; 

    EncoderParameter myEncoderParameter;

    EncoderParameters myEncoderParameters;

    // for the Quality parameter category.

    myEncoder = System.Drawing.Imaging.Encoder.Quality;

    // EncoderParameter object in the array.

    myEncoderParameters = new EncoderParameters(1);

    //设置质量 数字越大质量越好，但是到了一定程度质量就不会增加了，MSDN上没有给范围，只说是32为非负整数

    myEncoderParameter = new EncoderParameter(myEncoder, 100L);

    myEncoderParameters.Param[0] = myEncoderParameter;

④保存图像

    bitmap.Save(@"D:\Users\Administrator\Desktop\Piexl1.jpeg", myImageCodecInfo, myEncoderParameters);

MSDN上的给的例子：

using System; using System.Drawing; using System.Drawing.Imaging; class Example_SetJPEGQuality { public static void Main() { Bitmap myBitmap; ImageCodecInfo myImageCodecInfo; Encoder myEncoder; EncoderParameter myEncoderParameter; EncoderParameters myEncoderParameters; // Create a Bitmap object based on a BMP file. myBitmap = new Bitmap("Shapes.bmp"); // Get an ImageCodecInfo object that represents the JPEG codec. myImageCodecInfo = GetEncoderInfo("image/jpeg"); // Create an Encoder object based on the GUID // for the Quality parameter category. myEncoder = 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. myEncoderParameters = new EncoderParameters(1); // Save the bitmap as a JPEG file with quality level 25. myEncoderParameter = new EncoderParameter(myEncoder, 25L); myEncoderParameters.Param[0] = myEncoderParameter; myBitmap.Save("Shapes025.jpg", myImageCodecInfo, myEncoderParameters); // Save the bitmap as a JPEG file with quality level 50. myEncoderParameter = new EncoderParameter(myEncoder, 50L); myEncoderParameters.Param[0] = myEncoderParameter; myBitmap.Save("Shapes050.jpg", myImageCodecInfo, myEncoderParameters); // Save the bitmap as a JPEG file with quality level 75. myEncoderParameter = new EncoderParameter(myEncoder, 75L); myEncoderParameters.Param[0] = myEncoderParameter; myBitmap.Save("Shapes075.jpg", myImageCodecInfo, myEncoderParameters); } private static ImageCodecInfo GetEncoderInfo(String mimeType) { int j; ImageCodecInfo[] encoders; encoders = ImageCodecInfo.GetImageEncoders(); for(j = 0; j < encoders.Length; ++j) { if(encoders[j].MimeType == mimeType) return encoders[j]; } return null; } }