C# - Opencv应用(2) 之矩阵Mat使用[矩阵创建、图像显示、像素读取与赋值]
- 矩阵创建
- 图像显示与保存
- 像素读取与赋值
- 新建sample02项目,配置opencv4相关包,新建
.cs
进行测试
1.矩阵创建
//创建空白矩阵
var dst = new Mat()
//创建并赋值
var src = new Mat(new Size(128, 128), MatType.CV_8U, Scalar.All(125));
//图像拷贝
Mat dst = src.Clone();
2.图像显示与保存
private static void test_0()
{
//全黑
var mat = new Mat(new Size(600, 600), MatType.CV_8UC3, new Scalar(0, 0, 0));
Cv2.NamedWindow("black", 0);
Cv2.ImShow("black", mat);
// 全白
mat = new Mat(new Size(600, 600), MatType.CV_8UC3, new Scalar(255, 255, 255));
Cv2.NamedWindow("white", 0);
Cv2.ImShow("white", mat);
Cv2.ImWrite("white.jpg", mat);
}
3.像素读取与赋值
- 两种常用的图像遍历方式
private void GetSet()
{
using var mat = new Mat(ImagePath.Lenna, ImreadModes.Color);
for (int y = 0; y < mat.Height; y++)
{
for (int x = 0; x < mat.Width; x++)
{
Vec3b color = mat.Get<Vec3b>(y, x);
Vec3b newColor = new Vec3b(color.Item2, color.Item1, color.Item0);
mat.Set<Vec3b>(y, x, newColor);
}
}
Cv2.ImShow("Slow", mat);
Cv2.WaitKey(0);
Cv2.DestroyAllWindows();
}
/// <summary>
/// Reasonably fast
/// </summary>
private void GenericIndexer()
{
using var mat = new Mat(ImagePath.Lenna, ImreadModes.Color);
var indexer = mat.GetGenericIndexer<Vec3b>();
for (int y = 0; y < mat.Height; y++)
{
for (int x = 0; x < mat.Width; x++)
{
Vec3b color = indexer[y, x];
Vec3b newColor = new Vec3b(color.Item2, color.Item1, color.Item0);
indexer[y, x] = newColor;
}
}
Cv2.ImShow("GenericIndexer", mat);
Cv2.WaitKey(0);
Cv2.DestroyAllWindows();
}
- 灰度图操作
private static void test_1()
{
var img = new Mat(new Size(128, 128), MatType.CV_8U, 1);
var pixel = img.GetGenericIndexer<int>();
for (var y = 0; y < img.Height; y++)
{
for (var x = 0; x < img.Width; x++)
{
pixel[y, x] = x + y;
}
}
Cv2.NamedWindow("单通道",0);
Cv2.ImShow("单通道", img);
Cv2.WaitKey(0);
}
文章来源:https://www.toymoban.com/news/detail-776564.html
- 三通道图操作
private static void test_2()
{
//三通道
using (var src = new Mat(new Size(128, 128), MatType.CV_8UC3, new Scalar(20, 129, 250)))
using (var dst = new Mat())
{
for (var y = 0; y < src.Height; y++)
{
for (var x = 0; x < src.Width; x++)
{
var color = src.Get<Vec3b>(y, x);
var temp = color.Item0;
color.Item0 = color.Item2; // B <- R
color.Item2 = temp; // R <- B
src.Set(y, x, color);
}
}
src.CopyTo(dst);
Mat dat = dst.Clone();
Cv2.NamedWindow("dst", 0);
Cv2.ImShow("dst", dst);
Cv2.WaitKey(0);
}
}
文章来源地址https://www.toymoban.com/news/detail-776564.html
- 完整代码
using OpenCvSharp;
namespace OpenCVSharpSample01
{
class Program
{
static void Main(string[] args)
{
test_0();
test_1();
test_2();
}
private static void test_0()
{
var mat = new Mat(new Size(600, 600), MatType.CV_8UC3, new Scalar(0, 0, 0));
Cv2.NamedWindow("black", 0);
Cv2.ImShow("black", mat);
// 全白
mat = new Mat(new Size(600, 600), MatType.CV_8UC3, new Scalar(255, 255, 255));
Cv2.NamedWindow("white", 0);
Cv2.ImShow("white", mat);
Cv2.ImWrite("white.jpg", mat);
}
private static void test_1()
{
var img = new Mat(new Size(128, 128), MatType.CV_8U, 1);
var pixel = img.GetGenericIndexer<int>();
for (var y = 0; y < img.Height; y++)
{
for (var x = 0; x < img.Width; x++)
{
pixel[y, x] = x + y;
}
}
Cv2.NamedWindow("单通道",0);
Cv2.ImShow("单通道", img);
Cv2.WaitKey(0);
}
private static void test_2()
{
//三通道
using (var src = new Mat(new Size(128, 128), MatType.CV_8U, Scalar.All(125)))
using (var dst = new Mat())
{
for (var y = 0; y < src.Height; y++)
{
for (var x = 0; x < src.Width; x++)
{
var color = src.Get<Vec3b>(y, x);
var temp = color.Item0;
color.Item0 = color.Item2; // B <- R
color.Item2 = temp; // R <- B
src.Set(y, x, color);
}
}
src.CopyTo(dst);
Mat dat = dst.Clone();
Cv2.NamedWindow("dst", 0);
Cv2.ImShow("dst", dst);
Cv2.WaitKey(0);
}
}
}
}
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