python OpenCV output list

Question

I want to get a simple python list from the pixel colors from an image the output list should be monodimensional ordered as:

output = [B1,G1,R1,B2,G2,R2,B3,G3,R3....]

to get the image data:

import cv2
image = cv2.imread('a.png')
image
array([[[  0,   0, 255],
        [  0,   0, 255],
        [  0,   0, 255]],

       [[  0, 255,   0],
        [  0, 255,   0],
        [  0, 255,   0]],

       [[255,   0,   0],
        [255,   0,   0],
        [255,   0,   0]]], dtype=uint8)

f = image.flatten()
f
[array([  0,   0, 255,   0,   0, 255,   0,   0, 255,   0, 255, 0,   0,
       255,   0,   0, 255,   0, 255,   0,   0, 255,   0,   0, 255, 0,

0], dtype=uint8)]

is there a way to get:

f = [0,0,255,0,0,255,0,0,255,0,255,0,0,255,0,0,255,0,255,0,0,255,0,0,255,0,0]

f = f[0], does this work?

M4rtini
– M4rtini

2014-01-10 16:02:54 +00:00
Commented Jan 10, 2014 at 16:02 — M4rtini
– M4rtini, Commented Jan 10, 2014 at 16:02
maybe: list(f) or f =f.tolist()

user2841651
– user2841651

2014-01-10 16:04:22 +00:00
Commented Jan 10, 2014 at 16:04 — user2841651
– user2841651, Commented Jan 10, 2014 at 16:04

berak · Accepted Answer · 2014-01-10 17:02:54Z

1

since opencv images in cv2 are numpy arrays, use numpy:

import cv2
import numpy as np

# simulate a bgr image:
>>> a = np.array([[[1,2,3], [4,5,6]],[[1,2,3], [4,5,6]]])
>>> a
array([[[1, 2, 3],
        [4, 5, 6]],

       [[1, 2, 3],
        [4, 5, 6]]])
>>> b = np.reshape(a,-1)
>>> b
array([1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6])

edited Jan 10, 2014 at 17:02

answered Jan 10, 2014 at 16:25

berak

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user2239318 · Accepted Answer · 2014-01-13 16:27:10Z

-1

.tolist() method kindly adviced by Mr Abid Rahman

>>> import numpy as np
>>> f = np.random.randint(0,255,(3,3,3))
>>> print(f)
[[[193  61  68]
  [223 102   0]
  [ 45 204   7]]

 [[ 64 193  60]
  [ 94 157  49]
  [ 38 116   5]]

 [[ 64 107 197]
  [225 246  22]
  [186 102 156]]]
>>> g = f.flatten()
>>> print g
[193  61  68 223 102   0  45 204   7  64 193  60  94 157  49  38 116   5
  64 107 197 225 246  22 186 102 156]

>>> g.dtype
dtype('int32')
>>> type(g)
<type 'numpy.ndarray'>

>>> h = g.tolist()
>>> print h
[193, 61, 68, 223, 102, 0, 45, 204, 7, 64, 193, 60, 94, 157, 49, 38,
116, 5, 64, 107, 197, 225, 246, 22, 186, 102, 156]
>>> type(h)
<type 'list'>

answered Jan 13, 2014 at 16:27

user2239318

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