如何调整图像C＃的大小 [英] How to resize an Image C#

问题描述

由于大小，宽度和高度是< System.Drawing.Image 的code> Get（）属性；

如何调整Image对象的大小

As Size, Width and Height are Get() properties of System.Drawing.Image;
How can I resize an Image object at run-time in C#?

现在，我只是使用以下命令创建一个新的 Image ：

Right now, I am just creating a new Image using:

// objImage is the original Image
Bitmap objBitmap = new Bitmap(objImage, new Size(227, 171));

推荐答案

这将执行高质量的调整大小：

This will perform a high quality resize:

/// <summary>
/// Resize the image to the specified width and height.
/// </summary>
/// <param name="image">The image to resize.</param>
/// <param name="width">The width to resize to.</param>
/// <param name="height">The height to resize to.</param>
/// <returns>The resized image.</returns>
public static Bitmap ResizeImage(Image image, int width, int height)
{
    var destRect = new Rectangle(0, 0, width, height);
    var destImage = new Bitmap(width, height);

    destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);

    using (var graphics = Graphics.FromImage(destImage))
    {
        graphics.CompositingMode = CompositingMode.SourceCopy;
        graphics.CompositingQuality = CompositingQuality.HighQuality;
        graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
        graphics.SmoothingMode = SmoothingMode.HighQuality;
        graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

        using (var wrapMode = new ImageAttributes())
        {
            wrapMode.SetWrapMode(WrapMode.TileFlipXY);
            graphics.DrawImage(image, destRect, 0, 0, image.Width,image.Height, GraphicsUnit.Pixel, wrapMode);
        }
    }

    return destImage;
}

• wrapMode.SetWrapMode(WrapMode.TileFlipXY) 防止图像边界周围出现鬼影-幼稚的调整大小将对超出图像边界的透明像素进行采样，但是通过镜像图像，我们可以获得更好的采样（此设置非常引人注目）


• destImage。 SetResolution 保持DPI大小，无论其物理尺寸如何-减小图像尺寸或打印时可能会提高质量


• 合成控制像素如何与背景混合-可能不需要，因为我们只画一件事。
  
  
  
  
  • graphics.CompositingMode 确定源图像中的像素是覆盖还是与背景像素组合。 SourceCopy 指定在渲染颜色时，它将覆盖背景颜色。
  
  
  • graphics.CompositingQuality 确定分层图像的渲染质量级别。
  
  
  • wrapMode.SetWrapMode(WrapMode.TileFlipXY) prevents ghosting around the image borders -- naïve resizing will sample transparent pixels beyond the image boundaries, but by mirroring the image we can get a better sample (this setting is very noticeable)
  • destImage.SetResolution maintains DPI regardless of physical size -- may increase quality when reducing image dimensions or when printing
  • Compositing controls how pixels are blended with the background -- might not be needed since we're only drawing one thing.
    • graphics.CompositingMode determines whether pixels from a source image overwrite or are combined with background pixels. SourceCopy specifies that when a color is rendered, it overwrites the background color.
    • graphics.CompositingQuality determines the rendering quality level of layered images.

    锻炼读者（实际上，我只是认为为您做到这一点不是此功能的工作）。

    Maintaining aspect ratio is left as an exercise for the reader (actually, I just don't think it's this function's job to do that for you).

    此外，这是一篇不错的文章，描述了图像大小调整的一些陷阱。上面的功能将覆盖其中的大多数功能，但您仍然需要担心保存。

    Also, this is a good article describing some of the pitfalls with image resizing. The above function will cover most of them, but you still have to worry about saving.

    这篇关于如何调整图像C＃的大小的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！