图像裁剪不适用于tiff文件 [英] Image cropping not work with tiff-files

问题描述

我有想要裁剪为多边形的图像。我的电脑上的所有图像都正常，但我有tiff文件。如果我尝试裁剪这个 - 结果我看到拉伸的文件。

I have image that i wanna crop as polygon. With all images on my pc all work correct, but i have tiff files. If i try crop this - in result i see stretched piece of file.

var img = (Bitmap)(GetPageFromTiff(openFileDialog.FileName));

img = CropImage(img);
pictureBox.BackgroundImage = img;
pictureBox.BackgroundImageLayout = ImageLayout.Zoom;
pictureBox.Image = img;

private Image GetPage(string file) {
  Bitmap bitmap = (Bitmap) Image.FromFile(file);
  bitmap.SelectActiveFrame(FrameDimension.Page, 0);
  MemoryStream byteStream = new MemoryStream();
  bitmap.Save(byteStream, ImageFormat.Tiff);
  return Image.FromStream(byteStream);
}

public Bitmap CropImage(Image img) {

 GraphicsPath path = new System.Drawing.Drawing2D.GraphicsPath();
 var points = new Point[] {
  new Point(85, 1111), new Point(934, 1111), new Point(934, 952), new Point(1642, 952),
   new Point(1642, 2000), new Point(85, 2000), new Point(85, 1111)
 };
 GraphicsPath gp = new GraphicsPath();
 gp.AddPolygon(points.ToArray());

 Bitmap bmp1 = new Bitmap(2220, 2220);

 using(Graphics G = Graphics.FromImage(bmp1)) {
  G.Clip = new System.Drawing.Region(gp);
  G.DrawImage(img, 0, 0);
  G.Dispose();


 }
 pictureBox.Image = bmp1;
 return bmp1;
}

https://snag.gy/UI3ZiA.jpg [ ^ ]



我尝试过：



我尝试将tiff保存为png，bmp等。全都一样。 Tiff文件下载 http://www.filedropper.com/165173z [ ^ ]

推荐答案

如果我从Stack Overflow复制的代码： http：// stackoverflow .com / questions / 30954503 /如何裁剪多边形区域 - 从一个图像在winform-picturebox [ ^ ] br />
稍微调整以适合测试图像：

If I take the code you copied from Stack Overflow: http://stackoverflow.com/questions/30954503/how-to-crop-a-polygonal-area-from-an-image-in-a-winform-picturebox[^]
And tweak it slightly to fit a test image:

Point[] points = new Point[] { new Point(60, 10), new Point(100, 60), new Point(60, 110), new Point(10, 60), new Point(60, 10) };
GraphicsPath gp = new GraphicsPath();
gp.AddPolygon(points.ToArray());

Bitmap bmp1 = new Bitmap(120, 120);

using (Bitmap bmp0 = (Bitmap)Bitmap.FromFile(imagePath))
    {
    using (Graphics G = Graphics.FromImage(bmp1))
        {
        G.Clip = new System.Drawing.Region(gp);
        G.DrawImage(bmp0, 0, 0);
        bmp1.Save(imageOutPath, ImageFormat.Jpeg);
        }
    }

它工作正常 - 我在黑色图像中得到一个图像钻石。

查看您的区域，它不适合您的输出图像...这可以解释问题...

It works fine - I get a diamond of image inside a black image.
Looking at your region, it doesn't fit inside your output image...which may explain the problem...

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