C#中如何调整图像大小

1.首先要获取你想要调整大小的图像：

string path = Server.MapPath(“~/Images”);
System.Drawing.Image img = System.Drawing.Image.FromFile(string.Concat(path,”/3904.jpg”));
2.将图像转换为Bitmap：

Bitmap b = new Bitmap(img);
3.创建一个调整图像大小的方法

private static System.Drawing.Image resizeImage(System.Drawing.Image imgToResize, Size size)
{
    //获取图片宽度
    int sourceWidth = imgToResize.Width;
    //获取图片高度
    int sourceHeight = imgToResize.Height;
    float nPercent = 0;
    float nPercentW = 0;
    float nPercentH = 0;
    //计算宽度的缩放比例
    nPercentW = ((float)size.Width / (float)sourceWidth);
    //计算高度的缩放比例
    nPercentH = ((float)size.Height / (float)sourceHeight);      
   if (nPercentH < nPercentW)
        nPercent = nPercentH;
    else
     nPercent = nPercentW;
     //期望的宽度
     int destWidth = (int)(sourceWidth * nPercent);
     //期望的高度
     int destHeight = (int)(sourceHeight * nPercent);

   Bitmap b = new Bitmap(destWidth, destHeight);
     Graphics g = Graphics.FromImage((System.Drawing.Image)b);
     g.InterpolationMode = InterpolationMode.HighQualityBicubic;
     //绘制图像
     g.DrawImage(imgToResize, 0, 0, destWidth, destHeight);
     g.Dispose();
     return (System.Drawing.Image)b;
}

在上面的方法中，我们获取了位图图像，然后绘制了不同尺寸的图像(这里绘制出的图像是基于指定的纵横比)

4.调用上述方法，得到调整大小之后的图片：

1
System.Drawing. Image i = resizeImage(b, new Size(100, 100));
输出结果：