调整图像大小的最佳选项

尝试如下操作:

public Bitmap Resize(Bitmap originalImage, int newWidth)
{
    int newHeight = (int)Math.Round(originalImage.Height * (decimal)newWidth / originalImage.Width, 0);
    var destination = new Bitmap(newWidth, newHeight);
    using (Graphics g = Graphics.FromImage(destination))
    {
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.PixelOffsetMode = PixelOffsetMode.HighQuality;
        g.DrawImage(originalImage, 0, 0, newWidth, newHeight);
    }
    return destination;
}

我会使用wpf libs而不是gdi+libs。wpf libs的运行速度更快,我认为它们比gdi+libs产生更好的结果。

看看伯特兰·勒罗伊的这些优秀文章。

• Resizing images from the server using WPF/WIC instead of GDI+
• Server-side resizing with WPF: now with JPG
• The fastest way to resize images from ASP.NET. And it’s (more) supported-ish

创建新的 Bitmap 对象,然后使用 Graphics 对象,根据所需的调整大小引擎,以增大/减小的大小将旧图像重新绘制到新图像的缓冲区中。

// inImage is your original
Bitmap outImage = new Bitmap(newWid, newHei);

Graphics gfx = Graphics.FromImage(outImage);
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;

gfx.DrawImage(inImage,
   new Rectangle(0, 0, newWid, new Hei),
   new Rectangle(0, 0, inImage.Width, inImage.Height),
   GraphicsUnit.Pixel);