Opencv Resize

Resize, hay gọi cách khác là scale ảnh, là việc ta chỉnh kích thước ảnh về kích thước mới (có thể giữ tỉ lệ ảnh ban đầu hoặc không). OpenCV is released under a BSD license and hence its free for both academic and commercial use. It allows you to select a rectangle in an image, crop the rectangular region and finally display the cropped image. opencv_馬賽克效果 影像的解析度設定 / 影像之縮放 可以藉由 resize這個方法 void resize(InputArray src, OutputArray dst,. So, here is a very simple program with basically the same result. 現在很多場景需要使用的數字識別,比如銀行卡識別,以及車牌識別等,在AI領域有很多圖像識別算法,大多是居於opencv 或者谷歌開源的tesseract 識別. In contrast to interpolation in skimage. Please let me know if it is possible using opencv or it can be done by any other library in python. While there is certainly a lot of overlap (i. If we do the same enlargement using cubic interpolation, we can see that the quality improves, as seen in the following figure. In particular, OpenCV in-place operations require a contiguous array from Python to avoid unexpected results. Open Source Computer Vision Library. let scale it down. resize」が用意されています。 今回はそれを利用して画像を拡大・縮小してみました。. After missing their original target of transitioning to Intel Gallium3D by default for Mesa 19. this code will detect display size and resize your image to fit on it. This can be done by first finding facial landmarks. As told in the previous tutorial, OpenCV is Open Source Commuter Vision Library which has C++, Python and Java interfaces and supports Windows, Linux, Mac OS, iOS and Android. But if we want to resize the original image and convert it to binary data without saving the resized image and re-read it from the hard disk, how should we do it? Convert image to bytes. In that I want to resize an image by dragging mouse over a canvas. Your votes will be used in our system to get more good examples. Integrated GSoC project with CUDA backend; Experimental support for nGraph OpenVINO API. In this tutorial we will check how to flip an image, using Python and OpenCV. In this post, we used aligned images supplied in CelebA. Open Source Computer Vision Library. io/x/gocv" Package gocv is a wrapper around the OpenCV 4. inter_area interpolation method of resize. The 1st one is the degraded OpenCV logo, the 2nd picture is the mask that was needed to run FMM. This second tutorial will show you how to load an image with OpenCV and how to convert it to a GeeXLab texture for rendering. This entry was posted in Image Processing and tagged bi-linear interpolation, bicubic interpolation, image interpolation opencv python, interpolation, nearest neighbor interpolation on 15 Nov 2018 by kang & atul. resize(new_shape) which fills with zeros instead of repeated copies of a. Recently I’m studying computer vision, and I came across the resize function in OpenCV. Can't compile. Depth: The depth is a type of date in image. resize big image by width for example there are 5400×2700 pixels and want to display by 1000 pixel width. We load the image, and in line 5 select the width we would like for our resized image. blobFromImage is … False so why not put swapRB=True? Thanks for your help!. Access Rights Manager can enable IT and security admins to quickly analyze user authorizations and access permission to systems, data, and files, and help them protect their organizations from the potential risks of data loss and data breaches. Resizing an image can be done in many ways. Please see the new OpenCV guide here. Align and resize images: Next we need to align and resize images so the center of the eyes are aligned in all images. A series of convenience functions to make basic image processing functions such as translation, rotation, resizing, skeletonization, displaying Matplotlib images, sorting contours, detecting edges, and much more easier with OpenCV and both Python 2. this sample is show how to resize image…. my name ist mustafa im a student in germany and i have projekt with opencv. IplImage* image = c. Application: To resize bar-codes. In the previous tutorial, we have learned about OpenCV and done some basic image processing using it like grey scaling, color saturation, histogram, color spaces, RGB component etc. here we can learn how to add an image as a watermark in python, with help of OpenCV in python. In this post, we used aligned images supplied in CelebA. As told in the previous tutorial, OpenCV is Open Source Commuter Vision Library which has C++, Python and Java interfaces and supports Windows, Linux, Mac OS, iOS and Android. resize stole 60 days of my life. By continuing to use Pastebin, you agree to our use of cookies as described in the Cookies Policy. resize (grayscaleFrame. xfOpenCV: 50+ Most Needed OpenCV Functions Basic Functionality Geometric Transforms Image Processing and Filters Feature Detection and Classifiers 3D Reconstruction Motion Analysis and Tracking Absolute difference Scale/Resize Box Canny edge detection StereoLBM Mean Shift Tracking (MST). resize() function of OpenCV library cv2. rescale this function calculates the local mean of elements in each block of size factors in the input image. opencv resize报内存错误? 问题出现的原因是你的src2是CV_32S类型的。resize不支持CV_32S类型,具体原因不清楚。. Click Browse Build and navigate to your StaticLib Folder. New size of width and height are calculated from a percentage supplied as a 3th argument. Resizing, by default, does only change the width and height of the image. The actual implementations of the geometrical transformations, from the most generic remap() and to the simplest and the fastest resize() ,. So I need resize it. The size of the image can be specified manually, or you can specify the scaling factor. 3 as the preferred OpenGL Linux driver on Intel graphics hardware, this milestone has now been reached for Mesa 20. Read stories about Opencv Resize Python on Medium. GitHub Gist: instantly share code, notes, and snippets. opencv 將圖片依我所給的角度轉正 我需要一個function 依照我所給的角度(由別的function不斷產生)做出旋轉 希望還可以附上詳細的註解,因為我對旋轉的函式也都不適太熟悉. 总结:resize可以一次性将原图像变为任意不为0的尺寸,适合用来做归一化图像操作;而pyrDown与pyrUp适合做长宽比率不变得操作,且调用一次只能长和. In contrast to interpolation in skimage. As in any other signals, images also can contain different types of noise, especially because of the source (camera sensor). It can detect the shape even if it is broken or distorted a little bit. In OpenCV, you can choose between several interpolation methods. In our example, the image will be enlarged by a factor of 1. OpenCV is the best way to get started with understanding how applications like photo editor and smartphone's camera work under the hood. 0 have been released! Release highlights. OpenCV Python - Resize image Syntax of cv2. In OpenCV, a video can be read either by using the feed from a camera connected to a computer or by reading a video file. 75 times the dimensions of inImg with CV_INTER_LINEAR type of interpolation. size[0]) and then multiplying the original height (img. OpenCV Tutorial - Python API Image Processing OpenCV Python - Setup with Anaconda IDE OpenCV Python - Read and Display Image OpenCV Python - Save Image OpenCV Python - Get Image Size OpenCV Python - Resize Image OpenCV Python - Read Image with Transparency Channel OpenCV Python - Edge Detection OpenCV Python - Gaussian Blur. imshow() to display the image in a separate window. Go to File > New > Project and select JavaFX project Choose a name for your project and click Next. OpenCVの「cv::resize」を利用することで、画像をリサイズ出来ます。 これには、「バイリニア補間」や「バイキュービック補間」が実装されています。. All you have to specify is the size of the Gaussian kernel with which your image should be convolved. Using OpenCV, you can read an image and store it in a matrix. OpenCV is a framework written in C++. hconcat() to concatenate (combine) images vertically and horizontally with Python, OpenCV. In case when you specify the forward mapping , the OpenCV functions first compute the corresponding inverse mapping and then use the above formula. imshow('image',img) cv2. This article assumes Windows 10 has just been installed. 0 (zip - 80. We’re going to see in this tutorial a few basic operations with the images using Opencv with Python. This function takes at minimum five arguments ( original image, new image, NMIN, NMAX and normalization type ). In this tutorial we will check how to flip an image, using Python and OpenCV. python opencv resize image cv cv2. Aside from the beginning lines, handling frames from a video is identical to handling for images. Today we are going to take a…. There is a difference in pixel ordering in OpenCV and Matplotlib. The size of the image can be specified manually, or you can specify the scaling factor. 75 times the dimensions of inImg with CV_INTER_LINEAR type of interpolation. Resize and crop an image based on OpenCV detected faces. All you have to specify is the size of the Gaussian kernel with which your image should be convolved. 0 (zip - 80. Cropping is a fairly simple process using OpenCV. 2 and OpenCV version 4. Because the TheAILearner text is non-rectangular, we will be using OpenCV cv2. ㅡㅡ 일단 image 생성이때 자신이 resize하고 싶은 크기로 할당하는 것이 중점이다. Hi, Can anyone help me with streaming video from OpenCV (using Python, or C if necessary) into OBS? I've had a look at the API docs but they're rather bewildering to a new OBS user, and I can't find any similar examples. Opencv uses a lot of different redundant approaches to obtain the frames from whatever source, but it usually seems to prefer FFMPEG when available. flip() Rotate imag. Now add your OpenCV user library to your project and click Next. Now you decide to save all the points of this contour (the third element) in a data structure of your own. 3 release included the new oclmodule containing OpenCL implementations of some existing OpenCV algorithms. From Epic Wiki. The first step towards reading a video file is to create a VideoCapture object. To run the OpenCV program, enter the name of the program. I don't know how to apply the log transform but I am familiar with the formula that is applied to do so, the code portion of all of this is the confusing part of this endeavor. 0 Now Defaults To The New Intel Gallium3D Driver For Faster OpenGL. If I have an image called inImg and an image named outImg how can I resize outImg so that it is 75% the size of inImg?. In that I want to resize an image by dragging mouse over a canvas. The size of the image can be specified manually, or you can specify the scaling factor. Hi, Zhang Runze, Have you tried the blob = cv. Select the correct package for your environment:. OpenCV is used for all sorts of image and video analysis, like facial recognition and detection, license plate reading, photo editing, advanced robotic vision, optical character recognition, and a whole lot more. OpenCVが提供する回転はスケーリングも同時に行い,回転の中心位置を変更できます.この変換を表す変換行列は以下のようになります. ここで: この変換行列を計算するための cv2. In fact, to avoid sampling artifacts, the mapping is done in the reverse order, from destination to the source. 0; win-64 v4. 2 thoughts on " Changing Video Resolution using OpenCV-Python " k. Sign in Sign up Instantly share code, notes, and snippets. In fact, since OpenCV already has an implementation of the Not function and performance-wise it is better than the generic version of the equivalent Convert function call. imread('Test. Instead, create an Objective-C or C wrapper for C++ code. OpenCV has the "cvResize()" function to resize images easily. js application. Then you start a loop, calling the. By using the | operator you also need to specify if you would like the image to keep its aspect ratio (CV_WINDOW_KEEPRATIO) or not (CV_WINDOW_FREERATIO). imshow() to display the image in a separate window. Note that this behavior is different from a. imread() cv2. OpenCV was designed for computational efficiency and with a strong focus on real-time applications. NumPy is one of the most important libraries for scientific computing in Python. OpenCV is used for all sorts of image and video analysis, like facial recognition and detection, license plate reading, photo editing, advanced robotic vision, optical character recognition, and a whole lot more. CSDN提供了精准c++中opencv resize信息,主要包含: c++中opencv resize信等内容,查询最新最全的c++中opencv resize信解决方案,就上CSDN热门排行榜频道. here we can learn how to add an image as a watermark in python, with help of OpenCV in python. This blog provides complete guide for learning Image processing with OpenCV with all the Source Codes. 总结:resize可以一次性将原图像变为任意不为0的尺寸,适合用来做归一化图像操作;而pyrDown与pyrUp适合做长宽比率不变得操作,且调用一次只能长和. Last active Jan 9, 2016. for 2x, we duplicate each row and column 2 times. matlab opencv resize rotated by 180 michael scheinfeild on 27 May 2019 hello all mexOpenCV to compile opencv code and use opencv resize, it works good but i recive rotated image by 180, how i can correct this also i want input and output will be uint8 and not single here is cpp file. of Channels & Type of Image OpenCV C++. You should use a different framework like darknet or darkflow with tensorflow and use them with a GPU to have a real time detection with high frame rates. 总结:resize可以一次性将原图像变为任意不为0的尺寸,适合用来做归一化图像操作;而pyrDown与pyrUp适合做长宽比率不变得操作,且调用一次只能长和. 特徴点のマッチング - OpenCV-Python Tutorials 1 documentation 抽出精度を高めるため、グレースケール変換を行っています。 前項と同様に、画像サイズは一律200px × 200pxに変換して比較しています。. resize(image, (224, 224)) ? it is performed by blobFromImage no? 2) For me openCV gives you back a BGR image…and the default value for swapRB in cv2. Inside this guide, you'll learn basic image processing operations using the OpenCV library using Python. Important: This article is outdated (ZED SDK 1. imagewizard is a python based library for performing various image manipulations and operations. Parameters image ndarray. openCVでは画像のサイズが小さい、背景が単色で人物がはっきり映っているものだとそれなりの精度で検出できていました。 ただ、複雑な画像にになると誤認識が多くなってしまうようでした。 比べて、SSDはすごかった。. There are several ways equivalent ways to calculate the value of P. Your video will look much better…. OpenCV is a highly optimized library with focus on real-time applications. Esta función tiene dos formas de uso, con 3 y con 6 parámetros de entrada. NumPy is one of the most important libraries for scientific computing in Python. (Taking a rather big chunk (50000,50000,3) still won't work, but it will work on a (10000,10000,3) chunk) Closing video window using close "X" button in. 2 thoughts on “ Changing Video Resolution using OpenCV-Python ” k. 1과 2를 누르면 그림의 가로 세로가 1. CV_INTER_LINEAR); not clear parameter double scale, understand that it change scale, but it is not understand how it should be set tried, and 1 and 2, did not notice any difference Please tell me how to resize images. resize() function. 我想把一副图像中的像素值为30的点 都改为像素值为0,像素值不等于30的 都改为255,我写的程序是这样的,但是运行的时候总是会停止. Can't compile. 由於公司業務需要,需要開發一個客戶端程序,同時需要在xp這種老古董的機子上運行,故研究瞭如下幾個數字識別方案:ocr 識別的不同選擇方案. OpenCV Image Rotation. Following is the syntax of this method. Therefore you can use the OpenCV library even for your commercial applications. En otras palabras podemos cambiar la proporción y tamaño de una imagen. They do not change the image content but deform the pixel grid and map this deformed grid to the destination image. That is, when OpenCL runtime and a compatible device are available on a client machine, user may call cv::ocl::resize() instead of cv::resize() to use the accelerated code. edit flag offensive delete link more add a comment. 파이썬에서 OpenCV를 사용해서 다음과 같이. There are functions for rotating or flipping images (= ndarray) in OpenCV and NumPy, either of which can be used. We use cookies for various purposes including analytics. OpenCV can generate histograms for both color and gray scale images. R2 is effectively a weighted average of Q12 and Q22, while R1 is a weighted average of Q11 and Q21. This tutorial is visualized step by step and well-described each of them. The first step towards reading a video file is to create a VideoCapture object. There are several ways equivalent ways to calculate the value of P. 5 next at 1. read method of cv2. for 2x, we duplicate each row and column 2 times. Translation is the shifting of an image in either the x or y direction. Image size Be it the modem digital camera or the traditional film camera , as far as image quality is concerned the dimension of the image size is para mount. Align and resize images: Next we need to align and resize images so the center of the eyes are aligned in all images. The actual implementations of the geometrical transformations, from the most generic remap() and to the simplest and the fastest resize(), need to solve two main problems with the above formula:. So, what you actually want to do is to resize the area that you found to be the size of the template which is small. By continuing to use Pastebin, you agree to our use of cookies as described in the Cookies Policy. 0 (zip - 80. 2 with Cuda support + Ubuntu 12. 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. cv2 (old interface in old OpenCV versions was named as cv) is the name that OpenCV developers chose when they created the binding generators. Written in optimized C/C++, the library can take advantage of multi-core processing. Well, just flashed my jetson tk1 I want to start working with opencv, cuda and gpu with c ++ or python Do you recommend following these steps?. here we can learn how to add an image as a watermark in python, with help of OpenCV in python. You should use a different framework like darknet or darkflow with tensorflow and use them with a GPU to have a real time detection with high frame rates. Recently I'm studying computer vision, and I came across the resize function in OpenCV. 파이썬에서 OpenCV를 사용해서 다음과 같이. CV_8U)? Since for the blobFromImage it accepts the size of (Width, Height). OpenCV Python - Resize image Syntax of cv2. OpenCV for Windows (2. Open Source Computer Vision Library. The concept of interpolation is not explained here. OpenCV can display image but if your image bigger than your screen or your display window you can't see all your image. Image Processing » Geometric Image Transformations » resize 利用OpenCV對影像進行縮放 OpenCV resize函數在c++的定義 參數1. From Epic Wiki. cu file when including opencv. Adaptive thresholding is the method where the threshold value is calculated for smaller regions and therefore, there will be different threshold values for different regions. Thus providing a crucial step towards computer vision. Build process. We use these images in our iPhone App, Explore pages as well as our performer pages throughout the site: Old and Busted Way. imwrite() - Save Image; OpenCV cv2 Resize Image; OpenCV - Add or Blend Two Images; OpenCV - Write Text on Image - putText() Convert Image to Black and White (Binary) OpenCV cv2 Find Contours in Image; OpenCV CV2 - Capture Video from Camera. OpenCV follows BGR order, while matplotlib likely follows RGB order. bilateralFilter (img, 9, 75, 75) Result: Note that the texture on the surface is gone, but edges are still preserved. Resizing an image means change the dimensions of the image change either width of it or height of it or both at the same time. 75 times the dimensions of inImg with CV_INTER_LINEAR type of interpolation. Welcome to another OpenCV with Python tutorial. OpenCV - Reading Images - The Imgcodecs class of the package org. R2 is effectively a weighted average of Q12 and Q22, while R1 is a weighted average of Q11 and Q21. INTER_AREA: This is used when we need need to shrink an image. How do you use OpenCV to capture and image process frames so that you can build computer vision applications under Linux on the Beaglebone – I do this using the boneCV. By following users and tags, you can catch up information on technical fields that you are interested in as a whole. Resize and crop an image based on OpenCV detected faces. The following article will help you to resizing the images in python using OpenCV. The program used a webcam to check a bracket was in the right position and reported back a pass or a fail. Esta función tiene dos formas de uso, con 3 y con 6 parámetros de entrada. OpenCV Image Rotation. Return a new array with the specified shape. INTER_CUBIC (slow) & cv2. of Channels & Type of Image OpenCV C++. Application: To resize bar-codes. If n is smaller than the current container size, the content is reduced to its first n elements, removing those beyond (and destroying them). We can access height, width and number of channels from img. 1 and over 200 issues have been closed. How to Crop Video from Webcam using OpenCV There will undoubtedly be times when you need to crop your video to delete unnecessary information and draw your viewers' attention to the most important elements. 0 のcv::resizeでは、INTER_LANCZOS4 という列挙体の値が利用できて、これによりLanczos法による拡大縮小が行えます。 Lanczos法はさらに良い結果になる、らしいです。. resize big image by width for example there are 5400×2700 pixels and want to display by 1000 pixel width. In the next blog , we will discuss Bi-linear interpolation method. dsize 輸出影像的長寬大小. Open Source Computer Vision Library. imgcodecs provides methods to read and write images. Opencv resize. Syntax - cv2. How Tensorflow's tf. Rotating or Resizing an Image in OpenCV: Posted on 9th June, 2010 by Shervin Emami. OpenCV vs scikit-image: What are the differences? Developers describe OpenCV as "Open Source Computer Vision Library". It returns a tuple of height,width and channel(if image RGB color) ex:(height,width,channel) as (360,480,3) Different interpolation methods are used to resize the image. Build process. En otras palabras podemos cambiar la proporción y tamaño de una imagen. The following article will help you to resizing the images in python using OpenCV. OpenCV returns a pointer to the third element. 总结:resize可以一次性将原图像变为任意不为0的尺寸,适合用来做归一化图像操作;而pyrDown与pyrUp适合做长宽比率不变得操作,且调用一次只能长和. 7 and OpenCV 2. Redirect me to the updated tutorial. INTER_AREA: This is used when we need need to shrink an image. One more GSoC project has been integrated – it adds implementations of new background subtraction algorithms. imread("source. In this tutorial, you will learn how to use the ZED SDK to capture and display color and depth images from your ZED. Here, in this section, we will perform some simple object detection techniques using template matching. Therefore, when we display an image loaded in OpenCV using matplotlib functions, we may want to convert it into RGB mode. Therefore you can use the OpenCV library even for your commercial applications. OpenCV was designed for computational efficiency and with a strong focus on real-time applications. OpenCV reference OpenCV 2. subrahmanyam 23 Sep 2019 at 6:09 pm. The aim of this repository is to provide means to package each new OpenCV release for the most used Python versions and platforms. Skip to content. But there is another factor which is not obvious: choice of OpenCV version, and choice of C or C++ interface. OpenCV (Open Source Computer Vision Library) includes several hundreds of computer vision algorithms. Use cv::resize. OpenCV Tutorial - Python API Image Processing OpenCV Python - Setup with Anaconda IDE OpenCV Python - Read and Display Image OpenCV Python - Save Image OpenCV Python - Get Image Size OpenCV Python - Resize Image OpenCV Python - Read Image with Transparency Channel OpenCV Python - Edge Detection OpenCV Python - Gaussian Blur. It contains a description of the function and a small example. Esta función tiene dos formas de uso, con 3 y con 6 parámetros de entrada. downscale_local_mean¶ skimage. In this tutorial we will check how to read an image and convert it to gray scale, using OpenCV and Python. This post will be helpful in learning OpenCV using Python programming. Here I will show how to implement OpenCV functions and apply them in various aspects using some great examples. python opencv resize image cv cv2. cv2 is the OpenCV library and the numpy library is included as many times the image will be treated as an array. To build the libraries in Terminal. 推荐:Python编程->混合编程(C++,python,opencv)实现 对于一个程序宅来说,一直有想法把C++,opencv,python结合起来,python的并发性优点,opencv的图像处理算法的优点,C++的灵活,然后就开始了下面的旅程:. I think you need to see. We make this tutorial very easy to learn. Simple steps let you draw the rectangle inside the pictures and video sample. It provides all you need to work with. bug category: imgproc. here we can learn how to add an image as a watermark in python, with help of OpenCV in python. Obviously you’ll start by reading an image from disk, or grab it from a video frame and so on, similar to this: After that depending on the required transformation use any of the … Continue reading "How to Rotate and/or Flip (Mirror) Images in OpenCV". jpg") Now using the resize method with axis values:. La función de OpenCV resize permite cambiar el tamaño de una variable Mat de OpenCV. I was hoping I won't have to reinvent the wheel by doing a quick matlab-->openCV conversion but guess this is the best solution I have for a quick solution. Follow 4 views (last 30 days) michael scheinfeild on 27 May 2019. An easy way to calculate the value of P would be to first calculate the value of the two blue dots, R2, and R1. Thanks for your reponse. Geometric Image Transformations¶ The functions in this section perform various geometrical transformations of 2D images. Realtime Computer Vision with OpenCV Mobile computer-vision technology will soon become as ubiquitous as touch interfaces. rescale this function calculates the local mean of elements in each block of size factors in the input image. Documentation for opencv-python. 8 MB) Get Updates. resize(img,(width,height),fx,fy,interpolation) interpolationを指定することで拡大・縮小の補完方法を. In case when you specify the forward mapping , the OpenCV functions first compute the corresponding inverse mapping and then use the above formula. 9 (zip - 75. cu file when including opencv. 2 and trunk: cmake doesn't show CUDA options. Installation and Usage. imgcodecs provides methods to read and write images. Enumeration Type Documentation InterpolationFlags. In this section you will learn basic operations on image like pixel editing, geometric transformations, code optimization, some mathematical tools etc. INTER_LINEAR - a bilinear interpolation (used by default) INTER_AREA - resampling using pixel area relation. OpenCV Memory Management If you're new to OpenCV, you need to know exactly how to manage all the huge amounts of memory you're using. OK, I Understand. Resize or rescale image in OpenCV. # Resize frame of video to 1/4 size for. Resize an Image. How to select a specific area of the image (ROI) How to print or change…. OpenCV: 图像缩放(cv2. Check that you have read an image into that variable. 기본 원리는 기존 사진과 rate 만큼 크기가 변화한 사진이 있다면, 변화환 사진의 픽셀을 그 길이 만큼 참조하도록. R2 is effectively a weighted average of Q12 and Q22, while R1 is a weighted average of Q11 and Q21. How do you use OpenCV to capture and image process frames so that you can build computer vision applications under Linux on the Beaglebone – I do this using the boneCV. The aspect ratio can be or not preserved, based on the requirement, and with a little calculation of desired size. For example, say your compile command looks like this: g++ `pkg-config opencv --cflags` my_code. Re: openCV - display an image while analyzing a copy Reply #1 - May 23 rd , 2009, 6:03pm The two best ways to speed up a cv process while still displaying the captured image is to get the Intel Performance Primitives and to thread the analysis. 2 and trunk: cmake doesn't show CUDA options. In OpenCV, you can choose between several interpolation methods. In case when you specify the forward mapping , the OpenCV functions first compute the corresponding inverse mapping and then use the above formula. VideoCapture object by passing in the path to your input video file. And then modify the data of the image at a pixel level by updating the array values. Take a look at the resize function in the OpenCV documentation. In this post I'm sharing a couple of very simple tricks to perform an efficient Rotate or Flip (Mirror) operation on OpenCV Mat images.