First, get image pixels

1.1 Get/Set (missile)

Mat mat = new Mat("lenna.png", LoadMode.Color);

for (int y = 0; y < mat.Height; y++)
{
    for (int x = 0; x < mat.Width; x++)
    {
        Vec3b color = mat.Get<Vec3b>(y, x);
        byte temp = color.Item0;
        color.Item0 = color.Item2; // B <- R
        color.Item2 = temp;        // R <- Bmat.Set<Vec3b>(y, x, color); }}Copy the code

1.2 GenericIndexer german-russian co-operation (fast)

Mat mat = new Mat("lenna.png", LoadMode.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];
        byte temp = color.Item0;
        color.Item0 = color.Item2; // B <- R
        color.Item2 = temp;        // R <- Bindexer[y, x] = color; }}Copy the code

1.3 TypeSpecificMat (faster -)

Mat mat = new Mat("lenna.png", LoadMode.Color);

var mat3 = new Mat<Vec3b>(mat); // cv::Mat_<cv::Vec3b>
var indexer = mat3.GetIndexer();

for (int y = 0; y < mat.Height; y++)
{    
    for (int x = 0; x < mat.Width; x++)
    {
        Vec3b color = indexer[y, x];
        byte temp = color.Item0;
        color.Item0 = color.Item2; // B <- R
        color.Item2 = temp;        // R <- Bindexer[y, x] = color; }}Copy the code

Second, data conversion

2.1 Mat – > System. Drawing Bitmap

Mat mat = new Mat("foobar.jpg", ImreadModes.Color);

Bitmap bitmap = OpenCvSharp.Extensions.BitmapConverter.ToBitmap(mat);
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2.2 System. Drawing. The Bitmap – > Mat

Bitmap bitmap = new Bitmap("foobar.jpg");

Mat mat = OpenCvSharp.Extensions.BitmapConverter.ToMat(bitmap);

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2.3 Mat – > byte []

Mat mat = new Mat("foobar.jpg", ImreadModes.Color);

byte[] bytes1 = mat.ToBytes(".png");

byte[] bytes2;
Cv2.ImEncode(".jpg", mat, out bytes2);

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2.4 byte [] – > Mat

byte[] imageData = System.IO.File.ReadAllBytes("foobar.jpg");

Mat colorMat = Mat.FromImageData(imageData, ImreadModes.Color);
Mat grayscaleMat = Mat.FromImageData(imageData, ImreadModes.GrayScale);

Mat alt = Cv2.ImDecode(imageData, ImreadModes.GrayScale);
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