OpenCV interview questions
- Pradeep Kumar
- 05th May, 2021
- 923 Followers
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OpenCV is an Open source Computer Vision library developed, to begin with by Intel. You can grip OpenCV for Linux, Windows, and Mac OSX. There is a lot of but in short, documentation and examples; OpenCV provides hardware-accelerated APIs that very much aid in image analysis, motion detection, image processing, and machine learning. It is used in the demo applications in order to show that even with hardware acceleration; a memory leak can create every application useless.
OpenCV interview questions
1) Explain what is OpenCV?
OpenCV stands for Open Source Computer Vision Library is an open-source library using which is used to develop real-time computer vision applications such as image processing, video capture, and analysis, for example, face detection and object detection.
2) List some application of OpenCV?
Some of the applications of OpenCV are object detection, face recognition, medical diagnosis, etc.
3) For what sobel operation is used in OpenCV?
In OpenCV Sobel Operator is a discrete differentiation operator which is used for image processing, basically, it combines Gaussian smoothing and differentiation.
4) What are Erosion and Dilation in OpenCv?
In OpenCV, Erosion and Dilation are the two very common morphological image processing operations which is a procedure for modifying the geometric structure in the image.
5) Which language is best for OpenCV?
C/C++ language is best for OpenCV.
6) Which method of opencv is used to read image?
The cv2.imread() method of the Imgcodecs class is used in OpenCV to read an image.
7) How to install OpenCV for Python in Windows?
We can install OpenCV for Python in Windows by performing the following steps:
- Below Python packages are to be downloaded and installed to their default locations.
- Python 3.x (3.4+) or Python 2.7.x from here.
- Numpy package (for example, using pip install numpy command).
- Matplotlib (pip install matplotlib) (Matplotlib is optional, but recommended since we use it a lot in our tutorials).
- Install all packages into their default locations. Python will be installed to C:/Python27/ in case of Python 2.7.
- After installation, open Python IDLE. Enter import numpy and make sure Numpy is working fine.
- Download the latest OpenCV release from GitHub or SourceForge site and double-click to extract it.
- Goto opencv/build/python/2.7 folder.
- Copy cv2.pyd to C:/Python27/lib/site-packages.
- Open Python IDLE and type the following codes in the Python terminal. >>> import cv2 as cv >>> print( cv.__version__ )
8) How many types of image filters available in OpenCV ?
There are two types of image filters available in OpenCV:
- Linear filter
- Non-linear filter
9) What is OpenGL?
OpenGL stands for Open Graphics Library, it is an open-source cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API used to interact with GPU for achieving the hardware-accelerated rendering.
10) What is CUDA?
CUDA is a parallel computing platform developed by Nvidia that is consists of its own GPU for general computing.
11) Where opencv libraries are installed?
The OpenCV libraries will be installed in the /usr/local directory.
12) In OpenCV which function is used to draw line?
In OpenCV line() function is used to draw the line.
13) How many types of video filters in OpenCV?
Different types of video filters available in OpenCV are Blurring, Smoothing, Distortion, Warp Stabilizer, alpha extract, bilateral, color matrix, chrome hold, etc.
14) How to find threshold in images using OpenCV?
We can find the threshold of an image in OpenCV with the help of cv.threshold function.
15) What is Scharr Operator?
Scharr() Operator is an operator that is used to detect the second derivatives of an image in horizontal and vertical directions.
16) Which method of opencv is used to save image?
cv2.imwrite() method is the method of OpenCV that is used to save an image.
17) Which method of opencv is used to show image?
cv2.imshow() method is the method of OpenCV that is used to show an image.