调整图像大小C＃ [英] Resize an Image C#

问题描述

由于尺寸，宽度，身高是获取（）System.Drawing.Image对象的属性，结果
我该如何调整在运行时的Image对象在C＃。

现在，我只是创建一个新的图片使用：

  // objImage是原始图​​像
位图objBitmap =新位图（objImage，新的大小（227，171））;
 

解决方案

这将执行一个高品质的调整大小：

  ///＆LT;总结＆gt;
///将图像大小调整到指定的宽度和高度。
///＆LT; /总结＆gt;
///＆LT; PARAM NAME =形象＆gt;至调整图像大小和LT; /参数＆GT;
///＆LT; PARAM NAME =宽方式＆gt;的宽度调整到＆lt; /参数＆GT;
///＆LT; PARAM NAME =高度方式＆gt;以调整的高度＆LT; /参数＆GT;
///＆LT;收益方式＆gt;调整后的图像＆LT; /回报＆GT;
公共静态位图ResizeImage（图片形象，诠释的宽度，高度INT）
{
    VAR destRect =新的Rectangle（0，0，宽度，高度）;
    VAR destImage =新位图（宽，高）;    destImage.SetResolution（image.Horizo​​ntalResolution，image.VerticalResolution）;    使用（VAR图形= Graphics.FromImage（destImage））
    {
        graphics.CompositingMode = CompositingMode.SourceCopy;
        graphics.CompositingQuality = CompositingQuality.HighQuality;
        graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
        graphics.Smoothi​​ngMode = Smoothi​​ngMode.HighQuality;
        graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;        使用（VAR wrapMode =新ImageAttributes（））
        {
            wrapMode.SetWrapMode（WrapMode.TileFlipXY）;
            graphics.DrawImage（图像，destRect，0，0，image.Width，image.Height，GraphicsUnit.Pixel，wrapMode）;
        }
    }    返回destImage;
}
 

• <$c$c>wrapMode.SetWrapMode(WrapMode.TileFlipXY) prevents图像周围的边框鬼影 - 天真的大小调整采样透明像素以外的图像边界，但通过镜像图像，我们可以得到一个更好的样本（此设置是非常明显的）


• <$c$c>destImage.SetResolution保持DPI，无论物理尺寸 - 减少图像尺寸或打印时，可能会增加质量


• 像素合成控制如何混合的背景 - 可能并不需要，因为我们只画一件事。
  
  
  • <$c$c>graphics.CompositingMode确定从源图像中的像素是否覆盖或用背景象素被组合。 <一href=\"https://msdn.microsoft.com/en-us/library/system.drawing.drawing2d.compositingmode(v=vs.110).aspx\"><$c$c>SourceCopy指定当彩色呈现，它覆盖的背景颜色。
  
  
  • <$c$c>graphics.CompositingQuality决定分层图像的渲染质量水平。
  
  


• <$c$c>graphics.InterpolationMode决定了中间的计算两个端点之间的值


• <$c$c>graphics.SmoothingMode指定直线，曲线和填充区域边缘是否使用平滑（也称抗锯齿） - 可能只适用于矢量


• <$c$c>graphics.PixelOffsetMode绘制新的图像时，会影响渲染质量

保持纵横比作为练习留给读者（实际上，我不认为这是这个函数的工作是为你做的）。

此外，这是描述一些缺陷与图像大小调整好文章。上述功能将覆盖大多数人，但你仍然担心节能。

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

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

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

解决方案

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) 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.
• graphics.InterpolationMode determines how intermediate values between two endpoints are calculated
• graphics.SmoothingMode specifies whether lines, curves, and the edges of filled areas use smoothing (also called antialiasing) -- probably only works on vectors
• graphics.PixelOffsetMode affects rendering quality when drawing the new image

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).

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.

这篇关于调整图像大小C＃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！