opencv python picture codec

cv2.imdecode () function reads from a specified memory cache data and converts the data (decoded) into an image format; mainly for recovering the image data transmitted from the network.
cv2.imencode () function is to convert the image format (encoded) into a data stream, assigned to the memory cache; mainly for compressing image data format, to facilitate network transmission.

imdecode () use 

Reading image data from the network and converted into a picture format:

# -*- coding: utf-8 -*-
import numpy as np
import urllib
import cv2
 
url = 'https://www.baidu.com/img/bd_logo1.png?where=super'
resp = urllib.urlopen(url)
image = np.asarray(bytearray(resp.read()), dtype="uint8")
image = cv2.imdecode(image, cv2.IMREAD_COLOR)
cv2.imshow('URL2Image',image)
cv2.waitKey()

display image:

 

 

imencode () use

 

The picture coding into the cache, and saves it to:

# - * - Coding: UTF- . 8 - * - 
Import numpy AS NP 
Import the urllib 
Import CV2 
 
img = cv2.imread ( ' 0122.jpg ' ) 
# ' .jpg ' represents the current image img jpg format according encoded in different formats the result of encoding is not the same 
img_encode = cv2.imencode ( ' .jpg ' , IMG) [ . 1 ] 
# imgg = cv2.imencode ( ' .png ' , IMG) 
 
data_encode = np.array (img_encode) 
str_encode = data_encode.tostring () 
  
# save cache data locally
Open ( 'img_encode.txt', 'WB')   AS f:
    f.write(str_encode)
    f.flush()

imencode () + imdecode () use 

Save the picture to your local coding, decoding read local files restored to image formats:

# - * - Coding: UTF- . 8 - * - 
Import numpy AS NP 
Import the urllib 
Import CV2 
 
img = cv2.imread ( ' 0122.jpg ' ) 
# ' .jpg ' represents the current image img jpg format according encoded in different formats the result of encoding is not the same 
img_encode = cv2.imencode ( ' .jpg ' , IMG) [ . 1 ] 
# imgg = cv2.imencode ( ' .png ' , IMG) 
 
data_encode = np.array (img_encode) 
str_encode = data_encode.tostring () 
 
# save cache data locally, saved in txt format 
with open ('img_encode.txt', 'wb') as f:
    f.write(str_encode)
    f.flush()
 
with open('img_encode.txt', 'rb') as f:
    str_encode = f.read()
 
nparr = np.fromstring(str_encode, np.uint8)
img_decode = cv2.imdecode(nparr, cv2.IMREAD_COLOR)
cv2.imshow("img_decode", img_decode)
cv2.waitKey()

or

# - * - Coding: UTF- . 8 - * - 
Import numpy AS NP 
Import the urllib 
Import CV2 
 
img = cv2.imread ( ' 0122.jpg ' ) 
# ' .jpg ' represents the current image img jpg format according encoded in different formats the result of encoding is not the same 
img_encode = cv2.imencode ( ' .jpg ' , IMG) [ . 1 ] 
# imgg = cv2.imencode ( ' .png ' , IMG) 
 
data_encode = np.array (img_encode) 
str_encode = data_encode.tostring () 
 
# save cache data locally, saved in txt format 
with open ('img_encode.txt', 'wb') as f:
    f.write(str_encode)
    f.flush()
 
with open('img_encode.txt', 'rb') as f:
    str_encode = f.read()
 
image = np.asarray(bytearray(str_encode), dtype="uint8")
image = cv2.imdecode(image, cv2.IMREAD_COLOR)
cv2.imshow('img_decode',image)