如何使用c#裁剪图像?

查看这个链接:http://www.switchonthecode.com/tutorials/csharp-tutorial-image-editing-saving-cropping-and-resizing

private static Image cropImage(Image img, Rectangle cropArea)
{
Bitmap bmpImage = new Bitmap(img);
return bmpImage.Clone(cropArea, bmpImage.PixelFormat);
}

您可以使用[Graphics.DrawImage][1]从位图绘制裁剪图像到图形对象上。

Rectangle cropRect = new Rectangle(...);
using (Bitmap src = Image.FromFile("") as Bitmap)
{
using (Bitmap target = new Bitmap(cropRect.Width, cropRect.Height))
{
using (Graphics g = Graphics.FromImage(target))
{
g.DrawImage(src, new Rectangle(0, 0, target.Width, target.Height),
cropRect,
GraphicsUnit.Pixel);
}
}
}

这很简单:

• 创建一个具有裁剪大小的新Bitmap对象。
• 使用Graphics.FromImage为新位图创建一个Graphics对象。
• 使用DrawImage方法将图像绘制到具有负X和Y坐标的位图上。

假设您想要获取一个图像文件(JPEG、BMP、TIFF等)并将其裁剪，然后将其保存为一个较小的图像文件，我建议使用具有. net API的第三方工具。以下是我喜欢的一些流行的说法:

这里有一个裁剪图像的简单例子

public Image Crop(string img, int width, int height, int x, int y)
{
try
{
Image image = Image.FromFile(img);
Bitmap bmp = new Bitmap(width, height, PixelFormat.Format24bppRgb);
bmp.SetResolution(80, 60);


Graphics gfx = Graphics.FromImage(bmp);
gfx.SmoothingMode = SmoothingMode.AntiAlias;
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
gfx.PixelOffsetMode = PixelOffsetMode.HighQuality;
gfx.DrawImage(image, new Rectangle(0, 0, width, height), x, y, width, height, GraphicsUnit.Pixel);
// Dispose to free up resources
image.Dispose();
bmp.Dispose();
gfx.Dispose();


return bmp;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
return null;
}
}

比公认的答案更简单的是:

public static Bitmap cropAtRect(this Bitmap b, Rectangle r)
{
using (var nb = new Bitmap(r.Width, r.Height))
{
using (Graphics g = Graphics.FromImage(nb))
{
g.DrawImage(b, -r.X, -r.Y);
return nb;
}
}
}

并且它避免了&;Out of memory .内存不足"最简单答案的异常风险。

注意，Bitmap和Graphics是IDisposable，因此是using子句。

编辑:我发现这是好的与由Bitmap.Save或Paint.exe保存的png，但失败与由例如油漆店专业6保存的png -内容被移位。添加GraphicsUnit.Pixel会给出不同的错误结果。也许只是这些失败的png有问题。

使用bmp.SetResolution(image.HorizontalResolution, image .VerticalResolution);

这可能是必要的，即使你在这里实现了最佳答案 特别是如果你的图像真的很棒，分辨率不是96.0

我的测试示例:

    static Bitmap LoadImage()
{
return (Bitmap)Bitmap.FromFile( @"e:\Tests\d_bigImage.bmp" ); // here is large image 9222x9222 pixels and 95.96 dpi resolutions
}


static void TestBigImagePartDrawing()
{
using( var absentRectangleImage = LoadImage() )
{
using( var currentTile = new Bitmap( 256, 256 ) )
{
currentTile.SetResolution(absentRectangleImage.HorizontalResolution, absentRectangleImage.VerticalResolution);


using( var currentTileGraphics = Graphics.FromImage( currentTile ) )
{
currentTileGraphics.Clear( Color.Black );
var absentRectangleArea = new Rectangle( 3, 8963, 256, 256 );
currentTileGraphics.DrawImage( absentRectangleImage, 0, 0, absentRectangleArea, GraphicsUnit.Pixel );
}


currentTile.Save(@"e:\Tests\Tile.bmp");
}
}
}

在c#中裁剪图像非常简单。然而，做的东西，你将如何管理裁剪你的图像将会有点困难。

下面的示例是如何在c#中裁剪图像的方法。

var filename = @"c:\personal\images\horizon.png";
var img = Image.FromFile(filename);
var rect = new Rectangle(new Point(0, 0), img.Size);
var cloned = new Bitmap(img).Clone(rect, img.PixelFormat);
var bitmap = new Bitmap(cloned, new Size(50, 50));
cloned.Dispose();

有一个开源的c#包装器，托管在Codeplex上，名为Web图像裁剪 .

注册控件

<%@ Register Assembly="CS.Web.UI.CropImage" Namespace="CS.Web.UI" TagPrefix="cs" %>

调整

<asp:Image ID="Image1" runat="server" ImageUrl="images/328.jpg" />
<cs:CropImage ID="wci1" runat="server" Image="Image1"
X="10" Y="10" X2="50" Y2="50" />

例如，当按钮被点击时调用裁剪方法;

wci1.Crop(Server.MapPath("images/sample1.jpg"));

只有这个示例工作没有问题:

var crop = new Rectangle(0, y, bitmap.Width, h);
var bmp = new Bitmap(bitmap.Width, h);
var tempfile = Application.StartupPath+"\\"+"TEMP"+"\\"+Path.GetRandomFileName();




using (var gr = Graphics.FromImage(bmp))
{
try
{
var dest = new Rectangle(0, 0, bitmap.Width, h);
gr.DrawImage(image,dest , crop, GraphicsUnit.Point);
bmp.Save(tempfile,ImageFormat.Jpeg);
bmp.Dispose();
}
catch (Exception)
{




}


}

这是另一种方法。在我的情况下，我有:

• 2个数字上下控制(称为LeftMargin和TopMargin)
• 1图片盒(pictureBox1)
• 1个按钮，我称之为generate
• C:\imagenes\myImage.gif

在按钮内部，我有这样的代码:

Image myImage = Image.FromFile(@"C:\imagenes\myImage.gif");
Bitmap croppedBitmap = new Bitmap(myImage);
croppedBitmap = croppedBitmap.Clone(
new Rectangle(
(int)LeftMargin.Value, (int)TopMargin.Value,
myImage.Width - (int)LeftMargin.Value,
myImage.Height - (int)TopMargin.Value),
System.Drawing.Imaging.PixelFormat.DontCare);
pictureBox1.Image = croppedBitmap;

我尝试在Visual studio 2012使用c#。我从这个页面找到了这个解决方案

如果你正在使用AForge。网:

using(var croppedBitmap = new Crop(new Rectangle(10, 10, 10, 10)).Apply(bitmap))
{
// ...
}

这里是github上的工作演示

https://github.com/SystematixIndore/Crop-SaveImageInCSharp

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>


<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<link href="css/jquery.Jcrop.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>
<script type="text/javascript" src="js/jquery.Jcrop.js"></script>
</head>
<body>
<form id="form2" runat="server">
<div>
<asp:Panel ID="pnlUpload" runat="server">
<asp:FileUpload ID="Upload" runat="server" />
<br />
<asp:Button ID="btnUpload" runat="server" OnClick="btnUpload_Click" Text="Upload" />
<asp:Label ID="lblError" runat="server" Visible="false" />
</asp:Panel>
<asp:Panel ID="pnlCrop" runat="server" Visible="false">
<asp:Image ID="imgCrop" runat="server" />
<br />
<asp:HiddenField ID="X" runat="server" />
<asp:HiddenField ID="Y" runat="server" />
<asp:HiddenField ID="W" runat="server" />
<asp:HiddenField ID="H" runat="server" />
<asp:Button ID="btnCrop" runat="server" Text="Crop" OnClick="btnCrop_Click" />
</asp:Panel>
<asp:Panel ID="pnlCropped" runat="server" Visible="false">
<asp:Image ID="imgCropped" runat="server" />
</asp:Panel>
</div>
</form>
<script type="text/javascript">
jQuery(document).ready(function() {
jQuery('#imgCrop').Jcrop({
onSelect: storeCoords
});
});


function storeCoords(c) {
jQuery('#X').val(c.x);
jQuery('#Y').val(c.y);
jQuery('#W').val(c.w);
jQuery('#H').val(c.h);
};


</script>
</body>
</html>

用于上传和裁剪的c#代码逻辑。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using SD = System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;


namespace WebApplication1
{
public partial class WebForm1 : System.Web.UI.Page
{
String path = HttpContext.Current.Request.PhysicalApplicationPath + "images\\";
protected void Page_Load(object sender, EventArgs e)
{


}
protected void btnUpload_Click(object sender, EventArgs e)
{
Boolean FileOK = false;
Boolean FileSaved = false;


if (Upload.HasFile)
{
Session["WorkingImage"] = Upload.FileName;
String FileExtension = Path.GetExtension(Session["WorkingImage"].ToString()).ToLower();
String[] allowedExtensions = { ".png", ".jpeg", ".jpg", ".gif" };
for (int i = 0; i < allowedExtensions.Length; i++)
{
if (FileExtension == allowedExtensions[i])
{
FileOK = true;
}
}
}


if (FileOK)
{
try
{
Upload.PostedFile.SaveAs(path + Session["WorkingImage"]);
FileSaved = true;
}
catch (Exception ex)
{
lblError.Text = "File could not be uploaded." + ex.Message.ToString();
lblError.Visible = true;
FileSaved = false;
}
}
else
{
lblError.Text = "Cannot accept files of this type.";
lblError.Visible = true;
}


if (FileSaved)
{
pnlUpload.Visible = false;
pnlCrop.Visible = true;
imgCrop.ImageUrl = "images/" + Session["WorkingImage"].ToString();
}
}


protected void btnCrop_Click(object sender, EventArgs e)
{
string ImageName = Session["WorkingImage"].ToString();
int w = Convert.ToInt32(W.Value);
int h = Convert.ToInt32(H.Value);
int x = Convert.ToInt32(X.Value);
int y = Convert.ToInt32(Y.Value);


byte[] CropImage = Crop(path + ImageName, w, h, x, y);
using (MemoryStream ms = new MemoryStream(CropImage, 0, CropImage.Length))
{
ms.Write(CropImage, 0, CropImage.Length);
using (SD.Image CroppedImage = SD.Image.FromStream(ms, true))
{
string SaveTo = path + "crop" + ImageName;
CroppedImage.Save(SaveTo, CroppedImage.RawFormat);
pnlCrop.Visible = false;
pnlCropped.Visible = true;
imgCropped.ImageUrl = "images/crop" + ImageName;
}
}
}


static byte[] Crop(string Img, int Width, int Height, int X, int Y)
{
try
{
using (SD.Image OriginalImage = SD.Image.FromFile(Img))
{
using (SD.Bitmap bmp = new SD.Bitmap(Width, Height))
{
bmp.SetResolution(OriginalImage.HorizontalResolution, OriginalImage.VerticalResolution);
using (SD.Graphics Graphic = SD.Graphics.FromImage(bmp))
{
Graphic.SmoothingMode = SmoothingMode.AntiAlias;
Graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
Graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
Graphic.DrawImage(OriginalImage, new SD.Rectangle(0, 0, Width, Height), X, Y, Width, Height, SD.GraphicsUnit.Pixel);
MemoryStream ms = new MemoryStream();
bmp.Save(ms, OriginalImage.RawFormat);
return ms.GetBuffer();
}
}
}
}
catch (Exception Ex)
{
throw (Ex);
}
}
}
}

我正在寻找一个简单和快速的函数，没有额外的库来做这项工作。我尝试了攻击的解决方案，但我需要29.4秒来“提取”一个atlas文件的1195张图像。所以后来我用这种方法做了同样的工作，需要2.43秒。也许这个会有帮助。

// content of the Texture class
public class Texture
{
//name of the texture
public string name { get; set; }
//x position of the texture in the atlas image
public int x { get; set; }
//y position of the texture in the atlas image
public int y { get; set; }
//width of the texture in the atlas image
public int width { get; set; }
//height of the texture in the atlas image
public int height { get; set; }
}


Bitmap atlasImage = new Bitmap(@"C:\somepicture.png");
PixelFormat pixelFormat = atlasImage.PixelFormat;


foreach (Texture t in textureList)
{
try
{
CroppedImage = new Bitmap(t.width, t.height, pixelFormat);
// copy pixels over to avoid antialiasing or any other side effects of drawing
// the subimages to the output image using Graphics
for (int x = 0; x < t.width; x++)
for (int y = 0; y < t.height; y++)
CroppedImage.SetPixel(x, y, atlasImage.GetPixel(t.x + x, t.y + y));
CroppedImage.Save(Path.Combine(workingFolder, t.name + ".png"), ImageFormat.Png);
}
catch (Exception ex)
{
// handle the exception
}
}

对于任何愿意使用“不安全”;代码，你可以获得比标准System.Drawing.Graphics方法更好的性能，如果你使用Bitmap.Clone()甚至更好。

Just keep in mind 32bpp is the only format the methods support. (Other formats could work as long as 1 pixel is stored as 4bytes)

如果感兴趣，基准在下面。

public static class BitmapExtension
{
unsafe public static Bitmap Crop(this Bitmap bitmap, int left, int top, int width, int height)
{
Bitmap cropped = new Bitmap(width, height);
BitmapData originalData = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, bitmap.PixelFormat);
BitmapData croppedData = cropped.LockBits(new System.Drawing.Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, bitmap.PixelFormat);


int* srcPixel = (int*)originalData.Scan0 + (left + originalData.Width * top);
int nextLine = originalData.Width - width;


for (int y = 0, i = 0; y < height; y++, srcPixel += nextLine)
{
for (int x = 0; x < width; x++, i++, srcPixel++)
{
*((int*)croppedData.Scan0 + i) = *srcPixel;
}
}


bitmap.UnlockBits(originalData);
cropped.UnlockBits(croppedData);


return cropped;
}


unsafe public static Bitmap CropSmall(this Bitmap bitmap, int left, int top, int width, int height)
{
Bitmap cropped = new Bitmap(width, height);
BitmapData originalData = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, bitmap.PixelFormat);
BitmapData croppedData = cropped.LockBits(new System.Drawing.Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, bitmap.PixelFormat);


Span<int> srcPixels = new Span<int>((void*)originalData.Scan0, originalData.Width * originalData.Height);


int nextLine = originalData.Width - width;


for (int y = 0, i = 0, s = left + originalData.Width * top; y < height; y++, s += nextLine)
{
for (int x = 0; x < width; x++, i++, s++)
{
*((int*)croppedData.Scan0 + i) = srcPixels[s];
}
}


bitmap.UnlockBits(originalData);
cropped.UnlockBits(croppedData);


return cropped;
}
}

裁剪3440x1440到1000x1000

裁剪3440x1440到256x256

裁剪3440x1440到1440x1440