public Bitmap ChangeImgSize(Image bit, double Multiple)
{
Bitmap newBitmap = new Bitmap(Convert.ToInt32(bit.Width * Multiple), Convert.ToInt32(bit.Height * Multiple));
Graphics g = Graphics.FromImage(newBitmap);
g.Clear(Color.Transparent);
//设置画布的描绘质量
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.DrawImage(bit, new Rectangle(0, 0, newBitmap.Width, newBitmap.Height), 0, 0, bit.Width, bit.Height, GraphicsUnit.Pixel);
g.Dispose();
return newBitmap;
}