In [1]:

    

import cv2
import numpy as np


    

In [2]:

    

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


    

    




(225, 400, 3)

In [3]:

    

print(im.dtype)


    

    




uint8

In [4]:

    

cv2.imwrite('data/temp/lena.png', im)
im_png = cv2.imread('data/temp/lena.png')


    

In [5]:

    

print(np.array_equal(im, im_png))


    

    




True

In [6]:

    

cv2.imwrite('data/temp/lena.bmp', im)
im_bmp = cv2.imread('data/temp/lena.bmp')


    

In [7]:

    

print(np.array_equal(im, im_bmp))


    

    




True

In [8]:

    

print(np.array_equal(im_png, im_bmp))


    

    




True

In [9]:

    

cv2.imwrite('data/dst/lena_q25.jpg', im, [cv2.IMWRITE_JPEG_QUALITY, 25])
im_q25 = cv2.imread('data/dst/lena_q25.jpg')


    

In [10]:

    

print(np.array_equal(im, im_q25))


    

    




False

In [11]:

    

print(im.shape == im_q25.shape)


    

    




True

In [12]:

    

print(im.shape == (250, 400, 3))


    

    




False

In [13]:

    

im_diff = im.astype(int) - im_q25.astype(int)


    

In [14]:

    

print(im_diff.max())


    

    




142

In [15]:

    

print(im_diff.min())


    

    




-101

In [16]:

    

im_diff_abs = np.abs(im_diff)


    

In [17]:

    

print(im_diff_abs.max())


    

    




142

In [18]:

    

print(im_diff_abs.min())


    

    




0

In [19]:

    

cv2.imwrite('data/dst/lena_diff_abs.png', im_diff_abs)


    

    
Out[19]:





True

In [20]:

    

im_diff_abs_norm = im_diff_abs / im_diff_abs.max() * 255


    

In [21]:

    

print(im_diff_abs_norm.max())


    

    




255.0

In [22]:

    

print(im_diff_abs_norm.min())


    

    




0.0

In [23]:

    

cv2.imwrite('data/dst/lena_diff_abs_norm.png', im_diff_abs_norm)


    

    
Out[23]:





True

In [24]:

    

im_diff_center = np.floor_divide(im_diff, 2) + 128


    

In [25]:

    

print(im_diff_center.max())


    

    




199

In [26]:

    

print(im_diff_center.min())


    

    




77

In [27]:

    

cv2.imwrite('data/dst/lena_diff_center.png', im_diff_center)


    

    
Out[27]:





True

In [28]:

    

im_diff_center_norm = im_diff / np.abs(im_diff).max() * 127.5 + 127.5


    

In [29]:

    

print(im_diff_center_norm.max())


    

    




255.0

In [30]:

    

print(im_diff_center_norm.min())


    

    




36.81338028169013

In [31]:

    

cv2.imwrite('data/dst/lena_diff_center_norm.png', im_diff_center_norm)


    

    
Out[31]:





True

In [32]:

    

im_diff_bin = (im_diff_abs > 32) * 255


    

In [33]:

    

cv2.imwrite('data/dst/lena_diff_bin.png', im_diff_bin)


    

    
Out[33]:





True

In [34]:

    

print(list(zip(*np.where(im_diff_abs == np.max(im_diff_abs)))))


    

    




[(155, 117, 2)]

In [35]:

    

print(list(zip(*np.where(im_diff_abs > 100))))


    

    




[(135, 160, 0), (137, 157, 2), (155, 117, 2)]