Windows Forms:在C#中将图像转换成灰度图
本文翻译自Windows Forms: Convert an image into grayscale in C#
这篇文章向你展示在C# Windows窗体应用程序中如何将图像转换成灰度图。
创建一个新的Windows窗体应用程序项目，然后创建一个允许你可以打开图像，然后将图像转换成黑白图像的简单的UI，如下图所示：
Convert Image
为
Open按钮添加单击事件处理，允许你选择一个图像文件，然后将图像显示到PictureBox控件中。对应的代码如下所示：
private void btnOpen_Click(object sender, EventArgs e)
{
using (OpenFileDialog openFileDlg = new OpenFileDialog() { Filter = "Images|*.jpg" })
{
if (openFileDlg.ShowDialog() == DialogResult.OK)
{
picOriginal.Image = Image.FromFile(openFileDlg.FileName);
}
}
}
下一步，创建一个MakeGrayscale方法允许你在C#中将图像转换成灰度图如下：
// convert an image into grayscale in c#
public Bitmap MakeGrayscale(Bitmap original)
{
// You need to create a new bitmap with size the same as image original,
// then create a color matrix and convert a color image to grayscale with C#.
Bitmap newBmp = new Bitmap(original.Width, original.Height);
Graphics g = Graphics.FromImage(newBmp);
ColorMatrix colorMatrix = new ColorMatrix(
new float[][]
{
new float[] {.3f, .3f, .3f, 0, 0},
new float[] {.59f, .59f, .59f, 0, 0},
new float[] {.11f, .11f, .11f, 0, 0},
new float[] {0, 0, 0, 1, 0},
new float[] {0, 0, 0, 0, 1}
});
ImageAttributes img = new ImageAttributes();
img.SetColorMatrix(colorMatrix);
g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height), 0, 0, original.Width, original.Height, GraphicsUnit.Pixel, img);
g.Dispose();
return newBmp;
}
你需要创建一个和原图像一样大小的位图，然后创建一个颜色矩阵，并在C#中将彩色图转换成灰度图。
最后，为Convert按钮添加事件处理，允许你将图像转换成灰度图：
private void btnConvert_Click(object sender, EventArgs e)
{
picConvert.Image = MakeGrayscale((Bitmap)picOriginal.Image);
}
下面是窗体的完整实现代码：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ConvertImageIntoGrayscale
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
// convert an image into grayscale in c#
public Bitmap MakeGrayscale(Bitmap original)
{
// You need to create a new bitmap with size the same as image original,
// then create a color matrix and convert a color image to grayscale with C#.
Bitmap newBmp = new Bitmap(original.Width, original.Height);
Graphics g = Graphics.FromImage(newBmp);
ColorMatrix colorMatrix = new ColorMatrix(
new float[][]
{
new float[] {.3f, .3f, .3f, 0, 0},
new float[] {.59f, .59f, .59f, 0, 0},
new float[] {.11f, .11f, .11f, 0, 0},
new float[] {0, 0, 0, 1, 0},
new float[] {0, 0, 0, 0, 1}
});
ImageAttributes img = new ImageAttributes();
img.SetColorMatrix(colorMatrix);
g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height), 0, 0, original.Width, original.Height, GraphicsUnit.Pixel, img);
g.Dispose();
return newBmp;
}
private void btnOpen_Click(object sender, EventArgs e)
{
using (OpenFileDialog openFileDlg = new OpenFileDialog() { Filter = "Images|*.jpg" })
{
if (openFileDlg.ShowDialog() == DialogResult.OK)
{
picOriginal.Image = Image.FromFile(openFileDlg.FileName);
}
}
}
private void btnConvert_Click(object sender, EventArgs e)
{
picConvert.Image = MakeGrayscale((Bitmap)picOriginal.Image);
}
}
}
lena图像素材下载
图像处理中经常使用到的Lena图片 下载地址：
https://bellard.org/bpg/lena.html
Lena的图片
这个用于图像处理的Lena图像是用于图像处理中很好的研究素材，如下图所示：
http://www.lenna.org/
程序效果
程序效果展示
