Are defenders behind an arrow slit attackable? Mathematica cannot find square roots of some matrices? In this short How To article I have demonstrated some rudimentary examples of constructing an OpenCV Mat object from C++ array and vector data structures. Mat from byte-array (or stream) - which type/format? Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I am using the computer vision libraries in OpenCV - if anybody is familiar with these then maybe you can help ;) I am trying to estimate the fundamental matrix between two images, using cvFindFundamentalMat(). Better way to check if an element only exists in one array. Be careful with your pixel formats too - you need to make sure the Image/Bitmap instance really contains RGB8 data. I am not a C# developer, but I will do my best to help. What was the pixel format of the original data? Does a 120cc engine burn 120cc of fuel a minute? ; The only time a matrix will not be continuous is when it borrows data (except the data borrowed is continuous in the big matrix, e.g. Enabling Gradle minifying for OpenCv library in Android Studio, error: undefined reference to `cv::imread(std::string const&, int)', Stereo system - Get 3d position usind OpenCv, OpenCV Camera Calibration: very large k3 value in distCoeffs. All result are bad. @Nagilo: Hi I was wondering if you would be willing to share the code of your android app? getDataBuffer ()). OpenCv create 3 channel Mat from continuous data array, Create or Reshape OpenCV 3 Channel Mat From Array, Create CV_16UC1 Mat from byte array in java opencv, C++ OpenCV create Mat from SIGNED char array (not unsigned), OpenCV - how to create Mat from uint8_t pointer, opencv C++ create Mat object from android NV21 image data buffer, Call a C++ function from Python and convert a OpenCV Mat to a Numpy array, Android convert byte array from Camera API to color Mat object openCV. AlexanderShishkov (Jul 21 '12) edit. How can I create rgb image from uchar* ? Creating a Mat object explicitly. This enables providing continued free tutorials and content so, thank you for supporting the authors of these resources as well as thecodinginterface.com. 2014-02-25 01:57:56 -0500. Did neanderthals need vitamin C from the diet? Thanks, Asked: C++ Header file that declares a class and methods but not members? How to build C++17 application in old linux distro with old stdlib and libc? http://docs.opencv.org/modules/core/doc/basic_structures.html#mat-mat, OpenCv create 3 channel Mat from continuous data array, Android convert byte array from Camera API to color Mat object openCV, Create or Reshape OpenCV 3 Channel Mat From Array, opencv C++ create Mat object from android NV21 image data buffer, OpenCV - how to create Mat from uint8_t pointer, Call a C++ function from Python and convert a OpenCV Mat to a Numpy array, OpenCv Mat initialization from array not working. How to create a std::string directly from a char* array without copying? The image is created with some gray shade not the original one. Initialize the new header. How do I set a background color for the whole window of a Qt application? How to create a thread pool using boost in C++? If it is desired to actually copy an array's data into an OpenCV Mat object thus giving it it's own separately allocated data to work with you can utilize the memcpy function from the C++ standard library. Saving an image with unset pixels. so how can i pass a numpy array as an input to c++ function, than convert that array to Mat(opencv) in c++ and do the operations in c++ and return that Mat back to python script. Mat ocvImg = Highgui.imdecode(new MatOfByte(buffer), Highgui.IMREAD_UNCHANGED); Nice, works fine ;) If you post your code as an answer, I will check it so that you get the reputation. Copying Array Data Into an OpenCV Mat Object. It isn't necessary to specify size_t step because it is AUTO_STEP by default. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content. Your matrix holds 8 bit elements (that is what CV_8UC1 means). How to get good matches from the ORB feature detection algorithm? When you want a Mat out of a uchar array use. ocvImg.put(0, 0, buffer); instead of the imdecode, it is more straightforward. Where does the idea of selling dragon parts come from? Demosaicing with opencv. But note that these are not the same as the on-disk (typically compressed) formats, such as PNG, TIFF, and so forth. However, to demonstrate yet another way of constructing a Mat object I will utilize the Size class from OpenCV to specify the dimensions of the Mat object being constructed but, do note the order of dimensions are switched when using the Size object whereby the number of columns is supplied first then followed by the rows which differs from the rows then columns order of the previously shown Mat constructors. @Rui Marques, no. UPDATE2: For OpenCV Mat data continuity, it can be summarized as follows: Matrices created by imread(), clone(), or a constructor will always be continuous. C++ create png/bitmap from array of numbers, OpenCV 2.3: Convert Mat to RGBA pixel array, Pybind11: Create and return numpy array from C++ side, opencv conversion from a Mat element to IplImage *, What's the fastest way to extract non-zero indices from a byte array in C++, Create span of string_views from C string array, Incrementing and Decrementing Values in the UpDown Control in C++ WINAPI, Qt5 application wont draw any windows on Ubuntu, friend class and the scope of function arguments, Compile C++17 code on RedHat Linux Enterprise Developer Workstation. Each implementation calls Mat::create for a destination matrix. Therefore I would prefer creating an OpenCV Mat and put the received buffer (byte []) into that. Therefore, any changes made in the vector's data will be seen when using the Mat object also. You are creating a memory stream and using the JPEG codec to write a compressed version of the image into the buffer as if it were a file. Is this an at-all realistic configuration for a DHC-2 Beaver? For example, below I construct a Mat object with 11 rows and columns and of type CV_8U. opencv Mat's want consecutive memory, the internal representation is just a single uchar * . If you want OpenCV matrix to care about memory, then you should copy matrix (you can do it in many ways, e.g. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, What exactly is the problem? Manage SettingsContinue with Recommended Cookies. Errors running builder 'CDT Builder' when trying to build OpenCV for android samples, How to limit the number of FPS from camera. Some of our partners may process your data as a part of their legitimate business interest without asking for consent. Not the answer you're looking for? std::getline is reading line where specified delimiter is not present? it's a compressed png (headers and all, not pixels) inside the buffer. Another OpenCV idiom in this function, a call of Mat::create for the destination array, that allocates the destination array unless it already has the proper size and type. We can create a matrix with more than two dimensions. Change 16 bit grayscale image to Color Image using OpenCV and C++, Use Android Phone Camera As Web Cam with OpenCV/C++, Converting fftw library calls to OpenCV calls, OpenCV Error: Assertion failed (a_size.width == len), How to erase text from an image using OpenCV, Android OpenCV optimization - line detection is slow Hough Lines, OpenCV affine transformation won't perform, How can i use a Vector of Struct containing vector. Apart from array/vector we also need the original Mat's mat.size [array like] and mat.type() [int]. Mat element access. Maybe you can help me? updated Accepted answer. Thanks for contributing an answer to Stack Overflow! To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. OpenCV's cv::Mat has various flags so you can work with a variety of in-memory image formats. QGIS Atlas print composer - Several raster in the same layout. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page. This time I've varied the pixel intensity so it appears as a gradient from black at the top to white at the bottom. Now I can modify the greyArr elements to be all equal to zero but, this time when I show the created Mat object created from the array's original data the image is seen as the same mono-intensity grey color rather than the zero value representing all black. Copyright 2022 www.appsloveworld.com. OpenCV create Mat from byte array. OpenCv c++ Create a C wrapper for basic print mat function? When you pass external data into matrix constructor, the external data is not automatically deallocated, so you should take care of it. byte[] buffer; // read from stream .. Then you can just use the Bitmap.LockBits() method tog obtain a pointer to the underlying image data. How to crop an image in OpenCV using Python, Create a divx-encoded avi from frames using opencv, CopyFileExW fails with 0 for an existing file, What is this fallacy: Perfection is impossible, therefore imperfection should be overlooked. The following line will swap the channels: Here is link to docs: http://docs.opencv.org/modules/core/doc/basic_structures.html#mat-mat. Making statements based on opinion; back them up with references or personal experience. For example, below I construct a Mat object with 11 rows and columns and of type CV_8U. Which values of numpy array in Python correspond to Mat from OpenCV in Java? How does legislative oversight work in Switzerland when there is technically no "opposition" in parliament? The C++ code appears ok, in that this creates a matrix wrapper for the supplied image data, assuming the buffer is in the conventional RGB8 format. OpenCV C++: Create Column Range for Mat type data from indices stored in int vector, Opencv (JavaScript) Mat from Array doesn't work, How to store values from an array to a Mat in OpenCV, How to convert ANN_MLP algorithm api from c to c++, OpenCV - how to form up a .avi from a list of .ppm files. There are functions in OpenCV, especially from calib3d module, such as cv::projectPoints, that take an array of 2D or 3D points in the form of Mat. The major difference being you must call the data() method of the vector class like so. When you're writing OpenCV code in C++, you'll eventually want to pass whatever Mat objects you have into a function or a class method. You can do this using the << operator of Mat. Mat newImg = Mat (nImageHeight, nImageWidth, CV_8UC3 . size of row may be bigger than width multiplied by number of channels multiplied by size of data element. You just have to be careful that your array contains what you think it does. It appears the problem lies in Your C# code. Accepted answer. convertTo() don't convert a CV_8UC4 image to CV_8UC3. How to crop an image in OpenCV using Python. Create a divx-encoded avi from frames using opencv. How does JavaScript store null values internally? Creating a QImage from an XBM. using. if you need to initialize it with dynamic memory, just use a single float pointer: also, take care that your data pointer does not get deleted / goes out of scope before you're done with the Mat. in that case, you'll need to clone() it to achieve a deep copy: Copyright 2022 www.appsloveworld.com. OpenCV get pixel channel value from Mat image. So if ProcessImage is asynchronous or somehow caches your matrix (i.e. Assuming 32 bit ints, the first one, 111, should be enough to fill the array. Multi-dimensional Mat Object. 18. cv::Mat to QImage and back. You are passing it an array of ints. unsigned short array [220*220]//contain pixel values of image. Why do quantum objects slow down when volume increases? Otherwise, de-reference the previous data by calling Mat::release. To learn more, see our tips on writing great answers. 1. einzelne Zeile; 2. mehrere . in C++ i have the folloing for the contours. OpenCv Mat initialization from array not working, OpenCv Fastest way to make Mat Image from 1 D Array in C++. My code is below ; QRGB file is a fine result but not RGB file. The consent submitted will only be used for data processing originating from this website. BYTE * ptrImageData; //Image data is in this array passed to this function Mat newImg = Mat (nImageHeight, nImageWidth, CV_8UC3, ptrImageData); The image is created with some gray shade not the original one. You can do this using the << operator of Mat. Usually the stream is then decoded into a Bitmap like this: Bitmap bmp = BitmapFactory.decodeByteArray(buffer, 0, buffer.length); But this allocated and de-allocates memory all the time. Note that this constructor does not copy the buffer, so the buffer must remain valid for the duration of this Mat instance (or be copied). So you may want specify "step" as last argument of constructor. // bi-dimensional real (double precision) array real_2d_array matrix; The data layout in Mat is compatible with real_2d_array (and the majority of dense . Yes sorry, I was assuming a buffer filled with the pixels only. This time is it evident from the output that the data referenced in the Mat object is distinct from the original source array. Is there penalty for reference counting in Mat? const auto std::initializer_list difference between Clang and GCC, Help understanding const char* operators in c++. How would I load a Private / Public Key from a string / byte array or any other container. rev2022.12.11.43106. OpenCV create Mat from byte array. So you are getting an image in newImg? Try passing 8 bit unsigned elements: . Ok, so basically are the coordinates of a set of contours resized as it follows: coor = cnts.reshape( (len(cnts), 2))#cnts is the contours. For example, if I iterate over the source array and set each element to a constant value of say 100 then redisplay the Mat object named greyImg it's evident the greyImg Mat object is pointing to the same data due to it's appearance as a mono-intensity grey image. Note that this constructor does not copy the buffer, so the buffer must remain valid for the duration of this Mat instance (or be copied). Mat reshap = Mat (cnts); Mat coor . How is Jesus God when he sits at the right hand of the true God? The optional step argument is not required because our data pointer points to continuous memory. This method allocates data for a matrix if it is empty. Mat byteImage = Mat (rows, cols, CV_8UC3, image_uchar); in case of a 3 channel byte image. 2014-02-25 02:01:41 -0500. C++ Using the operator keyword with a template? When would I give a checkpoint to my D&D party that they can return to if they die? In this How To article I discuss and demonstrate construction of the OpenCV C++ Mat object from array and vector data types. I could not find a useful conversion. Next I copy the bytes of the initial C++ array named greyArr into the OpenCV data field. This typically involves converting the image to grayscale, as well as blurring it to remove superficial details. . Mat Col (28539, 97, CV_32F); is a OpenCV bi-dimensional (28539 rows, 97 columns) dense floating-point (CV_32F = float) array. Video element access. Check out: How the image matrix is stored in the memoryt. thecodinginterface.com earns commision from sales of linked products such as the books above. matman (Feb 22 '15) edit. Reconstructing Mat from array/vector. hi, how can I convert unsigned short array to Mat in opencv ? Yes, this is one way to create a Mat from a byte array. As always, I thank you for reading and please feel free to ask questions or critique in the comments section below. All rights reserved. I'm not convinced that the memory management in the original code is entirely correct either, but anyway the above will work provided the scope of the buffer ownership is within the lock and unlock method calls. Pixel data residing in the standard C++ vector can also be used to construct an OpenCV Mat object in a manner very similar to what is shown above in the array example. Python 2 OpenCV 2 - Convex Hull to close an open Canny Edge? getRaster (). What is the no-undefined-behavior way of deserializing an object from a byte array in C++11 (or later)? Create Mat object in a Java client, sent from a C++ server using opencv, optimized copying from an openCV mat to a 2D float array, OpenCV - Create CV_8UC3 (3 channel) Mat from BGRA output, OpenCV create a sequence from an array of uchar in an efficient way, OpenCV create YUV420 or grayscale Mat object from YUYV pixelformat video frame, Types 'cv::Mat' and 'int' are not compatible when create a Mat from array, efficient way to create an opencv mat from std::vector. http://docs.opencv.org/java/org/opencv/highgui/Highgui.html#imdecode(org.opencv.core.Mat,%20int). Disconnect vertical tab connector from PCB. That is, each element of the output array will be a concatenation of the elements of the input arrays, where elements of i-th input array are treated as mv [i].channels ()-element vectors. In the Load, Modify, and Save an Image tutorial you have already learned how to write a matrix to an image file by using the cv::imwrite () function. In the Load, Modify, and Save an Image tutorial you have already learned how to write a matrix to an image file by using the cv::imwrite () function. C++ How to create byte[] array from file (I don't mean reading file byte by byte)? Here the output image shows grey pixels varying in intensity from black to white when scanning visually from left to right. This has two important consequences: (i) it is extremely fast because there is no need to allocate memory and populate a new data structure but, (ii) since its just a pointer being shared then any modifications to the original source array is also seen when you query the data using accessor methods of the Mat object or display it graphically. Usually the stream is then decoded into a Bitmap like this: But this allocated and de-allocates memory all the time. In general you should take care about two things: I am not familiar with C#, but it seems to me that you release data right after ProcessImage call. Why is reading lines from stdin much slower in C++ than Python? Therefore I would prefer creating an OpenCV Mat and put the received buffer (byte[]) into that. We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. How do I create a tuple of N T's from an array of T? I tried this, but it doesn't work.. Mat image = new Mat(); VideoCapture camCapture = new VideoCapture(0); //then I read the capture from the camera camCapture.read(frame) Reading pixel values from a frame of a video. The method uses the following algorithm: If the current array shape and the type match the new ones, return immediately. However, for debugging purposes it's much more convenient to see the actual values. 1. The previously mentioned behavior of construction via passing a pointer from the source data to the data field of the Mat object holds when constructing using a vector as well. How were sailing warships maneuvered in battle -- who coordinated the actions of all the sailors? Again, the method of copying vector data into a Mat object is done in a similar fashion as seen in the array example utilizing the memcpy function. :Unknown signal", mem_fun_ref: unresolved overloaded function type. We and our partners use cookies to Store and/or access information on a device.We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development.An example of data being processed may be a unique identifier stored in a cookie. To the contrary with C API where an output image had to be created by the developer, an empty output Mat can be supplied to each function. vector<Point>cnts;//Retrieve the vector nested in the contours. Thanks, the link was 'slots' helpful although . The function cv::split does the reverse operation. OpenCV create YUV420 or grayscale Mat object from YUYV pixelformat video frame Types 'cv::Mat' and 'int' are not compatible when create a Mat from array efficient way to create an opencv mat from std::vector Which values for window size and number of pyramids are reasonable for calcOpticalFlowPyrLK? toBufferedImage (mat). If it is not empty and has the correct size and type, the method does nothing. getData (); Maybe there are some additional image parameters i need to consider before transforming to bytes? Below is an example of creating a Mat object from a standard C++ two dimensional (ie, nested) array of unsigned 8 bit integers representing grey scale color intensities from black (0) to white (255). If you allocate external data manually and 100% sure that it is continuous, then you may not pass step and rely on automatic step calculation. Could you attach the. How to edit/read pixel values in OpenCv from Mat variable? The Mat class is the workhorse of OpenCV for C++ with around twenty different constructors available providing significant flexibility for building a Mat object to represent image data from a variety of sources. The Mat function takes four parameters namely rows, columns, data type and . We can use array to initialize the constructor: int arr [3] = {4,3,2}; Mat L (3, arr, CV_8UC (1), Scalar::all (0)); We specified its dimension of 3, then pass a pointer containing the size for each dimension. The alglib almost-equivalent datatype is. How to update Mat with multiple channels? 0. Maybe you've switched the red and blue channels. If the image data is to outlive this code block, you will have to copy the buffer. IP camera video streaming using openCV in VC++. The C++ code appears ok, in that this creates a matrix wrapper for the supplied image data, assuming the buffer is in the conventional RGB8 format. Notice that even after filling every element of the vector with the constant value of 100 the Mat object is unphased and still shows the gradient of grey values from black to white. If you want to copy the data, you can do this: Mat two_rows=Mat (2, cols, CV16UC1, depthMap + linewidth * SELECTEDLINE).clone (); Niu ZhiHeng (Jul 23 '12) edit. Can I call a constructor from another constructor (do constructor chaining) in C++? If you need to shuffle channels in some other advanced way, use cv::mixChannels. and then due to lack of reshape as vector i move it to Mat. UPDATE2: Fr die Kontinuitt der OpenCV-Mat-Daten lsst sie sich wie folgt zusammenfassen: Matrizen, die von imread(), clone()oder einen Konstruktor erzeugt werden, sind immer kontinuierlich. Ready to optimize your JavaScript with Rust? 1. single row; 2. multiple rows with full original width) from an existing matrix (i.e. Why is processing a sorted array faster than processing an unsorted array? Setting Up OpenCV for C++ using CMake and VS Code on Mac OS, How To Compress and Extract Zip Files with Python, Building Computer Vision Projects with OpenCV 4 and C++: Implement complex computer vision algorithms and explore deep learning and face detection, How To Construct an OpenCV Mat Object from C++ Arrays and Vectors, Implementing a Serverless Flask REST API using AWS SAM, Bridging Node.js and Python with PyNode to Predict Home Prices, Intro to Machine Learning with Spammy Emails, Python and, SciKit Learn, Django Authentication Part 1: Sign Up, Login, Logout, OAuth 2.0 and Open ID Connect Cheat Sheet, High Level Introduction to Java for Developers, Aurora PostgreSQL Slow Query Logging and CloudWatch Alarms via AWS CDK, Django Authentication Part 4: Email Registration and Password Resets, How To Upload and Download Files in AWS S3 with Python and Boto3. but as you see, same problem here, imdecode will create a new Mat You are right. and then you can pass the rgbBuffer to OpenCV. In the United States, must state courts follow rulings by federal courts of appeals? Find pixel color out of cv::Mat on specific position. created out of . CopyFileExW fails with 0 for an existing file. For the purposes of this post, let's say we want to write a utility function that prepares a BGR888 Mat for edge detection. Hi! But that is not the data format that cv::Mat is expecting, so you will basically see garbage (compressed data interpreted as uncompressed). Or if you want to do it without copying of data, you can change Mat header for each frame as Andrey said . I try to create mat object from uchar* . I have uchar array so it is 8 bit. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Matrix should contain exactly one column, each row corresponds to a point, matrix type should be 32FC2 or 32FC3 correspondingly. External data may not be continuous, i.e. How to trim and center an object on the canvas keeping the background? llvm exceptions - RaiseException "? Code polisher / reformater for C, C++ or Fortran, Initialize an static member in an fully specialized class template, Detect program launch in another thread on linux, std::unique pointer and custom lambda deleter error. Central limit theorem replacing radical n with n. What properties should my fictional HEAT rounds have to punch through heavy armor and ERA? How to decrease the number of processed frames from a live video camera? I have to create a (openCV) image processing function in C++ and have to call that function from python using ctypes. Note that only a pointer to the array is passed to the constructor and stored inside the Mat object's data field. In this example I specify the dimensions, in rows and columns, of the Mat object being constructed as well as the data type of CV_8U indicating a single channel 8 bit unsigned integer, also defined as a uchar in OpenCV. Can you assign 3 channel image data to QCustomPlots ColorMap function? On the senders side (.NET C#) it's a PNG with 24bppRgb. Most new-style OpenCV functions and methods that produce arrays call this method for each output array. How to create a Racket mutable array from a C pointer to modify an OpenCV image? 374. android: how to put a column into Mat. However, for debugging purposes it's much more convenient to see the actual values. 2. add a comment. Creating a Mat object explicitly. But I just get a white-noise image because my image format seems wrong. Each implementation calls Mat::create for a destination matrix . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. score:1. As previously stated, the resulting output shows that the modification to the source array data is reflected when using the Mat object that was constructed from it. safely round-trip integers values with IEEE 754 floating point double precision data type, Mapping runtime types to a parallel class hierarchy with templates. Then using one of the constructors that take data's pointer, we can obtain original Mat. http://docs.opencv.org/java/org/opencv/highgui/Highgui.html#imdecode, Creative Commons Attribution Share Alike 3.0. is available in the matrix header. byte [] data = ((DataBufferByte) Java2DFrameUtils. I tried CV_8UC3(without conversion from CV_8UC4), CV_32SC3 and CV_32SC4. The information like size of the matrix, the method used for storing the matrix, the address at which the matrix must be stored etc. I then use the HighGUI library to display the Mat object populated with a gradient of intensities of grey pixels within a named window. Japanese girlfriend visiting me in Canada - questions at border control? And while the newly allocated arrays are always continuous, you still need to check the destination array because Mat::create does not always allocate a new matrix. But can you provide a sample code for that? Asking for help, clarification, or responding to other answers. All rights reserved. How to create a mat from bits in opencv for java? For completeness below is the entire main.cpp source file containing all examples from this article. I want to transform the Mat data in byte array to create ImageIcon to display in JLabel. Find centralized, trusted content and collaborate around the technologies you use most. In my Android app I'm streaming images (all of same size) over the network to the Android device. Reconstructing Mat from array/vector Apart from array/vector we also need the original Mat's mat.size [array like] and mat.type [int].Then using one of the constructors that take data's pointer, we can obtain original Mat.The optional step argument is not required because our data pointer points to continuous memory. Can several CRTs be wired in parallel to one oscilloscope circuit? Extract specified row from cv::Mat 0. I am trying to do the same conversion in java desktop with opencv 2.4.4. std::map::erase() - which overload is faster? Hot Network Questions Build 32 and 64 bit libraries for boost at sametime? If it is desired to actually copy an array's data into an OpenCV Mat object thus giving it it's own separately allocated data to work with you can utilize the memcpy function from the C++ standard library. Connect and share knowledge within a single location that is structured and easy to search. ; Der einzige Fall, in dem eine Matrix nicht kontinuierlich ist, ist, wenn sie Daten (auer den entliehenen Daten, die in der groen Matrix kontinuierlich sind, z.B. Mat is a class in OpenCV consisting of two data parts namely matrix header and a pointer to the matrix. What is the best way to create a sub array from an exisiting array in C++? The most significant 8 bits of 111 would go into position 1,1, and these are 0 s. So you get an element with value 0. But I just get a white-noise image because my image format . Unresolved inclusion in OpenCV+Android tutorial, build problems for android_binary_package - Eclipse Indigo, Ubuntu 12.04. lifetime of matrix is longer that ProcessImage call), then you should care about memory management. Is this the proper way of creating Mat from byte array? Given a System.Image.Drawing.Image instance, you can create a wrapper Bitmap object directly (or maybe use as, since it is a simple downcast). On the receivers side (Android) I'm currently initializing the Mat like this: if buffer is what you get from the stream, you still have to decode it first, no matter if you want a bitmap or a Mat as output.