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Convert an Image to Numpy Array in Python

In [4]:
import numpy as np
from PIL import Image, ImageOps, ImageStat
In [3]:
img = Image.open("../../home/media/poker/4h.png")
img
Out[3]:

You can use either numpy.asarray or numpy.array to convert an image to a numpy array. The resulting numpy array is a 3-dimensional array with the third/last dimention being the 3 channels (RGB) no matter the format of the image.

In [4]:
np.asarray(img)
Out[4]:
array([[[ 37,  62,  59],
        [149, 174, 171],
        [225, 238, 239],
        ...,
        [232, 250, 249],
        [217, 235, 234],
        [122, 156, 154]],

       [[127, 133, 134],
        [240, 246, 247],
        [244, 243, 246],
        ...,
        [239, 240, 243],
        [243, 244, 247],
        [218, 233, 236]],

       [[152, 158, 159],
        [245, 251, 252],
        [237, 236, 239],
        ...,
        [235, 236, 239],
        [235, 236, 239],
        [227, 242, 245]],

       ...,

       [[ 45,  66,  64],
        [153, 174, 172],
        [233, 237, 239],
        ...,
        [235, 239, 241],
        [226, 230, 232],
        [132, 157, 152]],

       [[ 24,  45,  43],
        [ 38,  59,  57],
        [105, 109, 111],
        ...,
        [119, 123, 125],
        [ 92,  96,  98],
        [ 37,  62,  57]],

       [[ 25,  55,  50],
        [ 17,  47,  42],
        [ 15,  38,  33],
        ...,
        [ 16,  40,  40],
        [ 16,  40,  40],
        [ 19,  53,  49]]], dtype=uint8)
In [9]:
arr = np.array(img)
arr
Out[9]:
array([[[ 37,  62,  59],
        [149, 174, 171],
        [225, 238, 239],
        ...,
        [232, 250, 249],
        [217, 235, 234],
        [122, 156, 154]],

       [[127, 133, 134],
        [240, 246, 247],
        [244, 243, 246],
        ...,
        [239, 240, 243],
        [243, 244, 247],
        [218, 233, 236]],

       [[152, 158, 159],
        [245, 251, 252],
        [237, 236, 239],
        ...,
        [235, 236, 239],
        [235, 236, 239],
        [227, 242, 245]],

       ...,

       [[ 45,  66,  64],
        [153, 174, 172],
        [233, 237, 239],
        ...,
        [235, 239, 241],
        [226, 230, 232],
        [132, 157, 152]],

       [[ 24,  45,  43],
        [ 38,  59,  57],
        [105, 109, 111],
        ...,
        [119, 123, 125],
        [ 92,  96,  98],
        [ 37,  62,  57]],

       [[ 25,  55,  50],
        [ 17,  47,  42],
        [ 15,  38,  33],
        ...,
        [ 16,  40,  40],
        [ 16,  40,  40],
        [ 19,  53,  49]]], dtype=uint8)

The resulting numpy array has the dimension (54, 37, 3) since the image has 3 channels (RGB).

In [10]:
arr.shape
Out[10]:
(54, 37, 3)

Points in the middle of th red heart has large values in the first (R) channel, which is as expected.

In [14]:
arr[8, 8, :]
Out[14]:
array([160,   0,  17], dtype=uint8)
In [13]:
arr[9, 9, :]
Out[13]:
array([159,   0,   8], dtype=uint8)
In [15]:
arr[10, 10, :]
Out[15]:
array([168,   0,  19], dtype=uint8)

References

https://stackoverflow.com/questions/384759/how-to-convert-a-pil-image-into-a-numpy-array

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