{"id":101108,"date":"2021-03-23T15:00:00","date_gmt":"2021-03-23T13:00:00","guid":{"rendered":"https:\/\/examples.javacodegeeks.com\/?p=101108"},"modified":"2022-07-07T15:29:49","modified_gmt":"2022-07-07T12:29:49","slug":"opencv-python-tutorial","status":"publish","type":"post","link":"https:\/\/examples.javacodegeeks.com\/opencv-python-tutorial\/","title":{"rendered":"OpenCV Python Tutorial"},"content":{"rendered":"

In this article, we will explain OpenCV for Python through examples.<\/p>\n

You can also check this tutorial in the following video:<\/p>\n

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\"\"<\/a>
OpenCV Python Tutorial – video<\/figcaption><\/figure>\n<\/div>\n

1. What is Computer Vision or CV<\/h2>\n

Computer vision is a field that seeks to develop techniques to help an artificial system to extract information from images and videos. It tries to replicate parts of the human vision so a system can process, analyze, and make use of these pieces of information. Systems like these are \u201cSelf-driving cars\u201d, \u201cRobotic Navigation\u201d, in Military and Medicine applications, etc.<\/p>\n

2. OpenCV for Python<\/h2>\n

OpenCV is an open-source library for computer vision. OpenCV supports different programming languages like Python, Java, C++, etc. It is integrated with the \u201cNumpy\u201d library which is optimized for numerical operations.<\/p>\n

3. Installing OpenCV for Python<\/h2>\n

First of all, it is necessary to have Python and PIP preinstalled. Next, you open the terminal and you type the command
pip install opencv-python<\/code>. When it finishes you will get a “Successfully installed” message.<\/p>\n

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\"opencv<\/a>
Fig. 1: Terminal Commands<\/figcaption><\/figure>\n<\/div>\n

4.Basic Operations<\/h2>\n

In this example, we will see how we can load an image with OpenCV for Python, view the image, apply a simple rotation of 45 degrees and then save it with a given name and extension of our choice.<\/p>\n

BasicOperations.py<\/em><\/span>

<\/div> <\/div><\/p>\n
import os\nimport cv2\nimport numpy\n\nimg = cv2.imread(\"flowers-5452263_640.jpg\", cv2.IMREAD_COLOR)\n\ncv2.imshow(\"Image\", img)\ncv2.waitKey(0)\n\nimg_center = tuple(numpy.array(img.shape[1::-1]) \/ 2)\nrotation_matrix = cv2.getRotationMatrix2D(img_center, 45, 1.0)\nimg = cv2.warpAffine(img, rotation_matrix, img.shape[1::-1], flags=cv2.INTER_LINEAR)\n\ncv2.imshow(\"Image\", img)\ncv2.waitKey(0)\n\nprint(os.listdir())\n\ncv2.imwrite(\"new_img.png\", img)\n\nprint(os.listdir())\n\ncv2.destroyAllWindows()\n<\/pre>\n