Opencv Mat From Pointer















Point2f points) Mat public Mat(opencv_core. mat can be used as a pointer I can't find mat. CvMat* cvGetMat( const CvArr* arr, CvMat* mat, int* coi = 0, int allowND ); The function cvGetMat returns matrix header for the input array that can be matrix - CvMat*, image - IplImage* or multi-dimensional dense array - CvMatND* (latter case is allowed only if allowND != 0). OpenCV - how to create Mat from uint8_t pointer. opencv cv :: Mat :: ptrを使った効率的なピクセルアクセス ポインタ 例 効率が重要な場合、 cv::Mat オブジェクトのピクセルを素早く処理するには、 ptr(int r) メソッドを使用して、行 r の先頭(0から始まるインデックス)へのポインタを取得します。. i used this. The aim of the Mat object is to represent a matrix. In OpenCV 3, the SimpleBlobDetector::create method is used to create a smart pointer. The idea is that each Mat object has its own header, however the matrix may be shared between two instance of them by having their matrix pointers point to the same address. The output must be contiguous memory layout to be processed by OpenCV block processing procedures. We do this using the << operator of Mat. The class SparseMat represents multi-dimensional sparse numerical arrays. pdf), Text File (. OpenCV (Open source computer vision) is a library of programming functions mainly aimed at real-time computer vision. at(Point(x, y)); For a 3 channel i. The simplest container is the Mat data type that can be Thus the pointer of the base. bitmapToMat is used to convert the Bitmap to Mat object. Mat is a n-dimensional dense array containing pointer to image matrix and a. Converting between ROS images and OpenCV images (Python) Description: This tutorial describes how to interface ROS and OpenCV by converting ROS images into OpenCV images, and vice versa, using cv_bridge. return pointer to the matrix element. The Jetson TX2 module features a powerful GPU that may be used for various image processing tasks. OpenCV is the Open Computer Vision. Mat¶ OpenCV has been around since 2001. still, there's a caveat: you have to make sure, your data_pointer does not go out of scope (or become otherwise invalid), before you finished uploading the borrowed. Such a sparse array can store elements of any type that Mat can store. How can i read 10 images from a folder using opencv. You will need to copy the memory back to CPU first. The usage is shown in the code below. #:German Shorthai Pointer Kitchen/Bath Ma by erman Shorthai Pointer Kitchen/Bath Mat Check Prices On Sale Discount Prices Online. CV_64FC1 is 64 bit floating point. Backward conversion from Mat to CvMat or. Using OpenCV with CUDA on the Jetson TX2¶. So if you trained your model on RGB layout then you definitely need to specify --reverse_input_channels to model optimizer. Finally, we use OpenCV to read in the image, and pass this image to the OCR engine using its SetImage method. 14, NAOqi SDK supports OpenCV 2. I like to play with images and graphics stuff and OpenCV offers a lot of features related to image processing. The most common types are: CV_8UC1 for 8-bit 1-channel grayscale images;. The simplest container is the Mat data type that can be Thus the pointer of the base. int* refcount; // other members}; The class Mat represents an n-dimensional dense numerical single-channel or multi-channel array. Otherwise, both histograms must have equal types and sizes. Converting Between cv::Mat and QImage or QPixmap In a previous article, I outlined how to compile OpenCV for Mac OS X and to build and run a small example. This tip helps programmers to use Windows function with OpenCV library. In our example, I install the OpenCV library in the I:\Cygwin\JNI\OpenCV-2. opencv is a c++ library, while your attempt at doing this is C, and it won't work. The ZED SDK provides its own sl::Mat class to store image data, with a structure and data types similar to OpenCV cv::Mat. bitmapToMat is used to convert the Bitmap to Mat object. In OpenCV 3, the SimpleBlobDetector::create method is used to create a smart pointer. I am going to use a function written by a friend of mine. How to return Opencv Mat object from native c++ to java ? whose return type is Mat class of opencv, as follows : Header and pointer of the Mat object in Open CV?. Instead, they just initialize the matrix header that points to the specified data, which means that no data is copied. The new C++ interface to OpenCV is a great addition to the very popular computer vision library. OpenCV would return a "linked list" type structure called CvSeq. If you install OpenCV library on Windows, you will see OpenCV officially provides wrappers for Python and Java but not for C#. ndarray? According to the OpenCV source file opencv\modules\python\src2\cv2. OpenCV returns a pointer to the third element. See the Ptr description for details. If an integer, then Description. Hi all, I'm a newby to dlib, so maybe my question is a bit dump. OpenCV is an open source C++ library focusing on computer vision launched in 1999 by Intel research. seem to realize that the Mat object already is a smart pointer and much, much more. Cheat sheets and much more inside thsi pdf. Get the best deal for Right Floor Mats & Carpets for Volkswagen Pointer from the largest online selection at eBay. OpenCV is an image processing library which contains a large collection of image processing functions. You can achieve this by following the steps below: Create vx_image with vxCreateImageFromHandle function that accepts a pointer to a region of native memory. Mat for the cv::Mat type. You decide to access the third element of this linked list. It differs from the above function only in what argument(s) it accepts. A question I got a lot after writing this post quite some time ago was "How to pass a processed image from OpenCV back to Unity?!" Obviously, that tutorial described just the way to pass images from Unity to C# (because of the nature of what it needed to do) and my answers in the …. Instead, they just initialize the matrix header that points to the specified data, which means that no data is copied. the full constructor taking the camera-specific preset, number of disparities and the SAD window size. However, if you need to write a simple image scan prefer the pointer method. ) before work on the corresponding vx_image object finishes. class) public class QRCodeDetector extends Pointer Nested Class Summary Nested classes/interfaces inherited from class org. Originally developed by Intel, it was later supported by Willow Garage then Itseez (which was later acquired by Intel). However the blob detection only finds the center of the hand/elbow blob ( the red dot in the pic) rather than where the hand is. MFC 기준 Include/Opencv2폴더 사용 하는 것을 권장 Core : Mat 클래스를 포함한 기본 자료 구조와 여러 함수가 공유하는 클래스 Highgui : 윈도우 화면과 마우스 등을 제어하는 사용자 인터페이스 함수 Imgporc :. In lots of cases, we have to use multiple functions, and passing images to other functions. Template "trait" class for OpenCV primitive data types. The idea is that each Mat object has its own header, however the matrix may be shared between two instance of them by having their matrix pointers point to the same address. I have been working on George Nebehay’s OpenTLD version to port it to python and it has given me a good amount of exposure to C++ and OpenCV with C++. OpenCV Example of How to Change Brightness and Contrast of an Image with Trackbars In the following example, I have added two trackbars to change the brightness and contrast of an image. The diagonal will be represented a. GetData() returns a pointer to the point grey image data. This project tries to solve the problem of processing big data of images on Apache Hadoop using Hadoop Image Processing Interface (HIPI) for storing and efficient distributed processing, combined with OpenCV, an open source library of rich image processing algorithms. OpenCV Example Code It is very simple to do that. I like to play with images and graphics stuff and OpenCV offers a lot of features related to image processing. You can use it to call OpenCV functions from your C# application without dealing with complexity of operating native code and data structures from managed code - Emgu the wrapper will do it for you through PInvoke. The ocvMxArrayToMat_{DataType} transposes and interleaves column major mxArray data into row major cv::Mat. Cross-compiling OpenCV from sources and using it in my Android apps has long time been on my todo list. Then the function copies the bin values of the source histogram to the destination histogram and sets the same bin value ranges as in src. opencv 에서 cv::Mat 는 제일 기초가 되는 자료구조이다. net or how to call Opencv functions from C# or vb. how to convert images from one color-space to another, like BGR \leftrightarrow Gray, BGR \leftrightarrow HSV etc. Originally developed by Intel, it was later supported by Willow Garage then Itseez (which was later acquired by Intel). Moreover, the copy operators will only copy the headers and the pointer to the large matrix, not the data itself. It mainly focuses on image processing, video capture and analysis including features like face detection and object detection. OpenCV would return a "linked list" type structure called CvSeq. OpenCV can work together with OpenVX* code by careful sharing of data objects. OpenCV is a cross-platform library using which we can develop real-time computer vision applications. // Title: OpenCV C++ Program to blur an image. mat can be used as a pointer I can't find mat. See the Ptr description for details. The 4 values rows, cols, type, and data are all that is required to represent an image buffer of any format as an OpenCV Mat. 1 for both compilation and cross-compilation. Outline• OpenCV Overview• Functionality• Programming with OpenCV• OpenCV on CPU & GPU• Mobile vision 2 3. How to return Opencv Mat object from native c++ to java ? whose return type is Mat class of opencv, as follows : Header and pointer of the Mat object in Open CV?. If you install OpenCV library on Windows, you will see OpenCV officially provides wrappers for Python and Java but not for C#. Usually just the 3 first on the list below are enough (for simple applications): opencv_core opencv_imgproc opencv_highgui opencv_ml opencv_video opencv_features2d opencv_calib3d opencv_objdetect opencv_contrib opencv_legacy opencv_flann To find out where the libs are:. a and so on) in C++ which uses OpenCV the normal way. OpenCV is written in C++. As the datatype of this array is 8 bit unsigned integers. Visual Studio detected memory leak for cv::Mat. Access pixel in an OpenCV Matrix using the data pointer and indexing - opencv-pixel-index. The important bit happens in Update(): in an unsafe block, we call OpenCVInterop. html#automatic-memory-management. The OpenCV user interface allows us to create windows, add images to it, and move, resize, and destroy it. Clone via HTTPS Clone with Git or checkout with SVN using the repository's web address. How to convert "cv::Mat" to "unsigned char*". Mat is a n-dimensional dense array containing pointer to image matrix and a. The following program gets input a 3D volume and outputs a slice of interest. a and so on) in C++ which uses OpenCV the normal way. Now i wanna use this data in LabView. Open Source Computer Vision Library Victor Eruhimov ITSEEZ Microsoft Computer Vision School 2. Matrix constructors that take data and step parameters do not allocate matrix data. Once the matrix is created we can assign the image to the matrix. However, if you need to write a simple image scan prefer the pointer method. OpenCV supports for detecting mouse events. 실수나 복소수로 구성된 벡터 혹은 매트릭스, 그레이 스케일 이나 칼라 이미지, 3차원 부피 voxel volumes, 벡터 필드 vector fields, 점의 집합 point clouds, 텐서 tensors, 히스토그램(고차원 히스트그램의 경우 SparseMat 를 사용하는 것이 더. OpenCV is an image processing library which contains a large collection of image processing functions. Get frame from video with libvlc smem and convert it to opencv Mat. •namedWindow is used for viewing. OpenCV 자료형 - Mat Class (5) 3. In general if you would want to transfer the buffer to OpenCV, you would first map the region, then build a OpenCV Mat header around it (like in the example code above) and finally call Mat::copyTo() to another Mat object. You invoke it. How OPEN CV is progessing day by day. Converting between QVideoframe and Opencv Mat. OpenCV is an open source C++ library focusing on computer vision launched in 1999 by Intel research. Difference between copyTo,clone and assignment operator in OpenCV/ How to copy or clone an image in opencv/ What are image headers. Therefore, how to call Opencv functions from. Otherwise, both histograms must have equal types and sizes. I have been working on George Nebehay's OpenTLD version to port it to python and it has given me a good amount of exposure to C++ and OpenCV with C++. Briefly, openCV is a library of functions which mainly focuses on image analysis, processing and evaluation. Actually Mat is a class and the image is actually stored in a pointer in the class. I am wondering what the proper way is to create a C++ pointer to a Gpumat. In OpenCV 3, the SimpleBlobDetector::create method is used to create a smart pointer. Mat for the cv::Mat type. Instead, the header pointing to m data or its sub-array is constructed and associated with it. seem to realize that the Mat object already is a smart pointer and much, much more. Hi, Im working with a camera, and the camera gives me the image in its own type of variable, that contains image width , height , depth , and other things. Also please study the OpenVino sample hello_autoresize_classification. 5 ? Pointer to the old-style IplImage image structure. remove all the opencv. A primitive OpenCV data type is one of unsigned char, bool, signed char, unsigned short, signed short, int, float, double or a tuple of values of one of these types, where all the values in the tuple have the same type. Books; Links; Platforms; Releases * OpenCV – 4. i used this. How to publish opencv Mat image in ROS Fuerte. CvImage to create a new instance of this class instead of using its pointer. It can be used to store data to such a file or read and decode the data. The fastest method turns out to be the LUT function. You can call BitmapToMat() function to convert C# Bitmap and use converted Mat to do image processing from OpenCV, so OpenCV will produce processed image as Mat type, here you can use MatToBitmap() function to return Bitmap type object back to C#. data - Pointer to the data source to be assigned to the matrix header. Mat for the cv::Mat type. Your second code snippet returns a pointer to the ith row of the image. Visual Studio detected memory leak for cv::Mat. please AVOID using pointers to cv::Mat, it's already a refcounted smartpointer on it's own. 2 (r4295) documentation » C++ Cheatsheet¶ The section is just a summary “cheatsheet” of common things you may want to do with cv::Mat:. This latest version contains various fixes and optimizations compared to the previously supported 2. Books; Links; Platforms; Releases * OpenCV – 4. Matrix constructors that take data and step parameters do not allocate matrix data. so I can test the pixel data before trying to output an opencv::Mat img ? a pointer to a. FFmpeg AVPacket to OpenCV Mat Converter When building computer vision projects in C++, you may find yourself in need for an FFmpeg to OpenCV packet converter. NET for Beginners (Emgu CV 3. In this tutorial, let's see how to identify a shape and position of an object using contours with OpenCV. About; Releases; Courses; Resources. However, the type of the argument for input image is "unsigned char *". So if this this is used within a function that returns a cv::Mat, one must put the Image rawImage and Image rgbImage declarations within the scope that the resulting converted image (cv::Mat) rather than within the function body or a segfault will result. Whilst we have used openCV packages in previous projects they have always been wrapped in an addon format, which obviously makes it easier to use but, for a forthcoming project we needed the ability to access the library directly. As the datatype of this array is 8 bit unsigned integers. The Mat is just a simple container for actual image data. A C/C++ DLL is given where i have a global Mat which contains data. I am wondering what the proper way is to create a C++ pointer to a Gpumat. No data is copied by these constructors. Outline• OpenCV Overview• Functionality• Programming with OpenCV• OpenCV on CPU & GPU• Mobile vision 2 3. Now we can convert cv::Mat to System. See the Ptr description for details. You will need to copy the memory back to CPU first. However the blob detection only finds the center of the hand/elbow blob ( the red dot in the pic) rather than where the hand is. Mat is a n-dimensional dense array containing pointer to image matrix and a. I am going to use a function written by a friend of mine. Hence, when using = operator to. •namedWindow is used for viewing. Instead, they just initialize the matrix header that points to the specified data, which means that no data is copied. net is different platform. With XIMEA cameras it is possible to stream data directly to the GPU memory without causing any overhead on the CPU. CvArr arr) Mat public Mat(opencv_core. Point2d points) Mat public Mat(opencv_core. This article explains how to use the SoftwareBitmap class, which is used by many different UWP APIs to represent images, with the Open Source Computer Vision Library (OpenCV), an open source, native code library that provides a wide variety of image processing algorithms. Think about it like this, if you already know how to use OpenCV then you can create a very simple library file (. The mxArray contains column major data and cv::Mat contains row major data. cxcore096d. My DLL return an unsigned short * pointer because I deal with uint8/16 images. The Jetson TX2 module features a powerful GPU that may be used for various image processing tasks. ppt), PDF File (. Tutorial: Basic GUI with OpenCV <2019-03-07 Thu> In this article, we are going to create a basic user interface with OpenCV. NET open source projects for wrapping OpenCV C++ APIs, and thus we don’t need to write a wrapper from scratch. opencv is a c++ library, while your attempt at doing this is C, and it won't work. Using OpenCV library in LabVIEW I then had to make use of a tiny app made by Reyn Vlietstra such that the. Pointer to the user data. The template class DataType is descriptive class for OpenCV primitive data types and other types that comply with the following definition. A C/C++ DLL is given where i have a global Mat which contains data. asked 2013-04-23 23:21:40 -0500. In this tutorial, we will compare the performance of the forEach method of the Mat class to other ways of accessing and transforming pixel values in OpenCV. Ptr encapsulates a pointer to a T instance and a reference counter associated with the pointer. Books; Links; Platforms; Releases * OpenCV – 4. The OpenCV Interface allows you to call OpenCV functions with mxArray. Accessing the pixels from Mat. We will show how forEach is much faster than naively using the at method or even efficiently using pointer arithmetic. About; Releases; Courses; Resources. Mat¶ OpenCV has been around since 2001. - Mat(C++)とCvMat(C)の変換 // Mat → CvMat 代入で変換. Mat img1; CvMat _img1 = img1; // CvMat → Mat コンストラクタで変換. CvMat img2; Mat _img2(img2); どちらの変換もデータはコピーされず参照する - Matの初…. To understand how to access, it is better to learn the data types first. Before being able to use the C++ interface, you must "include" the OpenCV namespace. Creating matrix in different ways in OpenCV, Basic steps to create new mat in OpenCV Learn OpenCV by Examples: Creating matrix in different ways Learn OpenCV by Examples. On line 13, we cast the input pointer to a Mat pointer. For the most part the learning curve is not step, but I tend to find myself doing things in to many steps only to realize that there is already a function for that particular task. You can then convert this into a cv::Scalar if you really need to, but the type of the cv::Mat::at instantiation must match the type of your image, since it just casts the image data without any conversions. Therefore, how to call Opencv functions from. ppt), PDF File (. How can you get data back from Push_back for vector in C++, Opencv? I copied some images to a vector in c++. Now i wanna use this data in LabView. Hi, OpenCV display function doesn't support GPU memory. Matrix constructors that take data and step parameters do not allocate matrix data. The Jetson TX2 module features a powerful GPU that may be used for various image processing tasks. By continuing to use Pastebin, you agree to our use of cookies as described in the Cookies Policy. Only users with topic management privileges can see it. with the native C++ code and share types like Mat from OpenCV. To tackle this issue OpenCV uses a reference counting system. We do not want to put additional stress to the. Pointer to the user data. Create Facemark Instance: In line 17 we create an instance of the Facemark class. Description. Now i wanna use this data in LabView. In a Simulink C-Mex S-function, real_T is basically double and not mxArray. About; Releases; Courses; Resources. Make sure that OpenCV cv::Mat object is not destroyed (or resized, etc. lib seem to be missing. 4+ and OpenCV 2. It is basically a pointer to memory, but it doesn't mean that the data is uchar. This operation is very efficient and can be used to process external data using OpenCV functions. dll means debug version of cxcore DLL and cxcored. //! pointer to the data. That callback function will be called every time, mouse events occur. You can call BitmapToMat() function to convert C# Bitmap and use converted Mat to do image processing from OpenCV, so OpenCV will produce processed image as Mat type, here you can use MatToBitmap() function to return Bitmap type object back to C#. Mat can be used to create n dimensional matrices. OpenCV - Reading Images - The Imgcodecs class of the package org. OpenCV (1) - Free download as Powerpoint Presentation (. uchar* data; //! pointer to the reference counter; // when array points to user-allocated data, the pointer is NULL. In a Simulink C-Mex S-function, real_T is basically double and not mxArray. This is because the OpenCV library is multi-thread enabled via Intel Threaded Building Blocks. Since version 1. (Mat image, List0 means a diagonal above the main one, <0 - below the main one). See the Ptr description for details. return pointer to the matrix element. How can you get data back from Push_back for vector in C++, Opencv? I copied some images to a vector in c++. lib and ending with opencv_videostab2413d. That is, Ptr ptr encapsulates a pointer to a T instance and a reference counter associated with the pointer. For this purpose, there are special constructors taking pointers to CvMat or IplImage and the optional flag indicating whether to copy the data or not. In our image analysis, we convert the mat color space from one type to another use ImgProc. To tackle this issue OpenCV uses a reference counting system. The following tip shows how to assign iplimage and mat variable to picturebox image. Actually Mat is a class and the image is actually stored in a pointer in the class. - Mat(C++)とCvMat(C)の変換 // Mat → CvMat 代入で変換. Mat img1; CvMat _img1 = img1; // CvMat → Mat コンストラクタで変換. CvMat img2; Mat _img2(img2); どちらの変換もデータはコピーされず参照する - Matの初…. #:German Shorthai Pointer Kitchen/Bath Ma by erman Shorthai Pointer Kitchen/Bath Mat Check Prices On Sale Discount Prices Online. We then create a pointer to an instance of the TessBaseAPI class. Description. Mat_ as Template Container; Matrices with More than Two Dimensions; Mat as Smart Pointer. Notice that by default the OpenCV uses BGR color space for color images, while the OpenVX supports only RGB channel order, so you might need format conversion, see example above. The created Mat object can be defined in a number of ways using the member functions. If you want a image format ( in C) to be general and work on almost any depth, it is good practice to store it all in this way. The class SparseMat represents multi-dimensional sparse numerical arrays. The usage is shown in the code below. The OpenCV Interface allows you to call OpenCV functions with mxArray. The diagonal will be represented a. Instead, they just initialize the matrix header that points to the specified data, which means that no data is copied. I want to pass unsigned char* directly from CU files to opencv cv::cuda::gpumat In one of the sample(v4l2cuda) , in multimedia api, in capture. Simply all the images are created from set of bytes, therefore it is necessary to create System. OpenCV (Open source computer vision) is a library of programming functions mainly aimed at real-time computer vision. How to convert "cv::Mat" to "unsigned char*". CvArr arr) Mat public Mat(opencv_core. Actually Mat is a class and the image is actually stored in a pointer in the class. I was not too busy to write it, but just enjoying my last semester at the campus. The mxArray contains column major data and cv::Mat contains row major data. Then in Libraries(-l) add the OpenCV libraries that we may need. The other interesting thing you can see in the code is the CvInvoke class. Hi guys, In contrast, you need to pass the id/pointer of the texture from unity script to cpp, and bind the. A question I got a lot after writing this post quite some time ago was “How to pass a processed image from OpenCV back to Unity?!” Obviously, that tutorial described just the way to pass images from Unity to C# (because of the nature of what it needed to do) and my answers in the …. With XIMEA cameras it is possible to stream data directly to the GPU memory without causing any overhead on the CPU. 1 for both compilation and cross-compilation. Here is a single channel array with 8 bit unsigned integers. It consists of a matrix header and a pointer to the matrix which contains pixels values. How to convert "cv::Mat" to "unsigned char*". opencv documentation: Setting and getting pixel values of a Gray image in C++. net is different platform. txt) or view presentation slides online. Things to know: (1) The code will only compile in Linux environment. seem to realize that the Mat object already is a smart pointer and much, much more. OpenCV is an image processing library which contains a large collection of image processing functions. This operation is very efficient and can be used to process external data using OpenCV functions. Mat is a reference-counted header to a shared data buffer. I was not too busy to write it, but just enjoying my last semester at the campus. This mask holds values that will adjust how much influence neighboring pixels (and the current pixel) have on the new pixel value. Automatic Allocation of the Output Data. cpp, there is a function (to call cuda kernel) for passing the V4L2 userptr static unsigned char * cuda_out_buffer = NULL; static void process_image (void *p). But there is a little difference, is the install directory. And the first thing to remember about Mat is to treat it as a smart pointer (like shared_ptr), instead of an ordinary class (like double) or container (like std::vector). In general if you would want to transfer the buffer to OpenCV, you would first map the region, then build a OpenCV Mat header around it (like in the example code above) and finally call Mat::copyTo() to another Mat object. Detailed Description. OpenCV library can be integrated into visual studio. MFC 기준 Include/Opencv2폴더 사용 하는 것을 권장 Core : Mat 클래스를 포함한 기본 자료 구조와 여러 함수가 공유하는 클래스 Highgui : 윈도우 화면과 마우스 등을 제어하는 사용자 인터페이스 함수 Imgporc :. Mat_ as Template Container; Matrices with More than Two Dimensions; Mat as Smart Pointer. OpenCV iteration method 2a – raw pointer with Vec3b and pointer helpers : 826061 (usecs) : 497 % of min OpenCV iteration method 2b – raw pointer with Vec3b and pointer helpers + continuous : 824629 (usecs) : 496 % of min OpenCV iteration method 3 – raw pointer access with raw step : 166014 (usecs) : 100 % of min. Fortunately, there are many. opencv documentation: Pixel Access in Mat. Let's look at the code! Tutorial 2 Images are stored in the Mat structure. The Mat is just a simple container for actual image data. CvImage to create a new instance of this class instead of using its pointer. Moreover, the copy operators will only copy the headers and the pointer to the large matrix, not the data itself. OpenVino samples usually use OpenCV to read in images and yes, OpenCV returns BGR. It is just a pointer after all. This topic has been deleted. fast way for converting from opencv mat to texture2d. Untill this point everything works. return pointer to the matrix element. 1 Cheat Sheet (C++) Mat 2D dense array (used as both a matrix SparseMat Multi-dimensional sparse array Ptr Template smart pointer class Matrix Basics. OpenCV 3, the Mat object. data - Pointer to the data source to be assigned to the matrix header. This is because the OpenCV library is multi-thread enabled via Intel Threaded Building Blocks. You can then convert this into a cv::Scalar if you really need to, but the type of the cv::Mat::at instantiation must match the type of your image, since it just casts the image data without any conversions. This can be helpful for preprocessing CS 1173: MATLAB reshape function. It is open source library for image processing.