Opencv learning (I) -- environment building

Learning goals

Occasionally looked at the recruitment , Many enterprises have some requirements for audio and video , Then enter the door first , Whole opencv To learn , The camera of the raspberry pie I just bought has arrived ,usb The camera has arrived , There is also a single-chip camera module , Learn all about , Now the environment is not good , Workers , It still needs to be more cost-effective , To find the way .

I didn't say I was leaving , Don't think much .

Installation environment

I studied under the virtual machine , Installation is ubuntu22.04 Version of .
System download address

First installed ssh service

sudo apt-get install openssh-server

This is not installed primarily to use command-line Software , It's about winscp It's easier to copy things .

Install pre dependency Software

sudo apt-get install cmake gcc g++ python3-dev python3-numpy libavcodec-dev libavformat-dev libswscale-dev libgstreamer-plugins-base1.0-dev libgstreamer1.0-dev libgtk-3-dev

Install some image dependent Libraries ：

sudo apt-get install libpng-dev libjpeg-dev libopenexr-dev libtiff-dev libwebp-dev 

download opencv Source code

git clone https://gitclone.com/github.com/opencv/opencv

Compile source code

cd opencv
mkdir build
cd bulid
cmake ../

Probably need 2 Hours , Bloggers who refer to blogs spend five hours , It seems that my computer is still rich

Final installation

sudo make install

Then roll back printing , Check it out. cv2 Installation position of

Then the output python3 Let's see if the environment is included

 python3 -c "import sys; print(sys.path)"
['', '/usr/lib/python310.zip', '/usr/lib/python3.10', '/usr/lib/python3.10/lib-dynload', '/home/xxx/.local/lib/python3.10/site-packages', '/usr/local/lib/python3.10/dist-packages', '/usr/lib/python3/dist-packages']

/usr/local/lib/python3.10/dist-packages Included , Just right , There is no need to add .

install pip

pip Mainly for python Install the module using

apt-get install python3-pip

install matplotlib modular

python3 -m pip install -U matplotlib

Matplotlib yes Python Drawing library of , It makes it easy for users to graph data , And provide a variety of output formats .
Matplotlib It can be used to draw all kinds of static , dynamic , Interactive charts .
Matplotlib It's a very powerful one Python drawing tools , We can use this tool to present a lot of data more intuitively in the form of charts .
Matplotlib You can draw a line diagram 、 Scatter plot 、 Contour map 、 Bar chart 、 Histogram 、3D graphics 、 Even graphic animation and so on .

Program testing

A test program , Pay attention to it python3 Command line

import matplotlib
import numpy as np
import cv2
from matplotlib import pyplot as plt
img = cv2.imread('/home/sunjin/work/123.jpg',0)
plt.imshow(img, cmap = 'gray', interpolation = 'bicubic')
plt.xticks([]), plt.yticks([])  # to hide tick values on X and Y axis
plt.show()

Because it is grayscale display , So the head of the plunger turned gray
The original picture is this

Camera test

First, configure the in the virtual machine USB To configure , Change it to 3.0.

then USB The device is connected to the virtual machine , That is, disconnect from the host .

#!/usr/bin/python3
#1. introduce cv2
import cv2

#2. The main function 
#if __name__ == '__main__':

#3. Turn on the laptop camera 
cap = cv2.VideoCapture(0)
assert cap.isOpened(), 'Cannot capture source' # If the camera does not open normally, an error is reported 

#4. If the camera can be turned on, the image frame can be obtained , Display images 
while cap.isOpened():
    #read() Function returns two parameters , The first parameter is bool value , Indicates whether the image is obtained ,
    # The second parameter is the current frame image 
    ret, frame = cap.read()
    #  Flip the acquired water products in the current frame 
    #  The second parameter ： 1  Indicates a horizontal flip ; 0  Indicates a vertical flip ;  Less than 0  Indicates a horizontal or vertical flip 
    frame = cv2.flip(frame,1)
    cv2.imshow('mycreame',frame)  # Displays the current frame 
    if ( cv2.waitKey(30)  == 27 ):   # Press down Esc Key to exit  waitKey() Method to wait for keyboard input , The unit is millisecond 
        break
#5. Close all windows 
cv2.destroyAllWindows()

Partial screenshots , So as not to cause discomfort

everything , All I owe is study

Reference blog
B Standing Octopus radish cat 《Ubuntu Compile and install under environment OpenCV-Python》

Conclusion

Today, the epidemic situation in Haidian has been upgraded , All employees work at home , Everyone's life pressure is getting bigger again . Always say you don't want to go to work , If you really don't go to work , According to the minimum standard of treatment in Beijing , It's time to feel bad again .

therefore , It's an old saying , Study , Never betray you , Our leaders said , If the company asks me not to come tomorrow , I can always find my next job , True or false, no judgment , But this confidence , Or we all have to learn . What confidence comes from ？ It has to be ability , What are we waiting for? , It's over .