In [1]:

    

import cv2


    

In [2]:

    

im = cv2.imread('data/src/lena.jpg')


    

In [3]:

    

print(type(im))


    

    




<class 'numpy.ndarray'>

In [4]:

    

print(im.shape)


    

    




(225, 400, 3)

In [5]:

    

print(im.dtype)


    

    




uint8

In [6]:

    

im[:, :, (0, 1)] = 0


    

In [7]:

    

cv2.imwrite('data/dst/lena_opencv_red.jpg', im)


    

    
Out[7]:





True

In [8]:

    

cv2.imwrite('data/dst/lena_opencv_red_high.jpg', im, [cv2.IMWRITE_JPEG_QUALITY, 100])


    

    
Out[8]:





True

In [9]:

    

cv2.imwrite('data/dst/lena_opencv_red_low.jpg', im, [cv2.IMWRITE_JPEG_QUALITY, 50])


    

    
Out[9]:





True

In [10]:

    

im_gray = cv2.imread('data/src/lena.jpg', cv2.IMREAD_GRAYSCALE)
# im_gray = cv2.imread('data/src/lena.jpg', 0)


    

In [11]:

    

print(type(im_gray))


    

    




<class 'numpy.ndarray'>

In [12]:

    

print(im_gray.shape)


    

    




(225, 400)

In [13]:

    

print(im_gray.dtype)


    

    




uint8

In [14]:

    

cv2.imwrite('data/dst/lena_opencv_gray.jpg', im_gray)


    

    
Out[14]:





True

In [15]:

    

im_gray_read = cv2.imread('data/dst/lena_opencv_gray.jpg')


    

In [16]:

    

print(im_gray_read.shape)


    

    




(225, 400, 3)

In [17]:

    

import numpy as np


    

In [18]:

    

print(np.array_equal(im_gray_read[:, :, 0], im_gray_read[:, :, 1]))


    

    




True

In [19]:

    

print(np.array_equal(im_gray_read[:, :, 1], im_gray_read[:, :, 2]))


    

    




True

In [20]:

    

im = cv2.imread('xxxxxxx')


    

In [21]:

    

print(im)


    

    




None

In [22]:

    

# print(im.shape)
# AttributeError: 'NoneType' object has no attribute 'shape'


    

In [23]:

    

im = cv2.imread('data/src/sample.csv')


    

In [24]:

    

print(im)


    

    




None

In [25]:

    

im = cv2.imread('xxxxxxx')


    

In [26]:

    

if im:
    print('Image is read.')
else:
    print('Image is not read.')


    

    




Image is not read.

In [27]:

    

im = cv2.imread('xxxxxxx')


    

In [28]:

    

if not im:
    print('Image is not read.')
else:
    print('Image is read.')


    

    




Image is not read.