PIL image to array (numpy array to array) - Python

Question

I have a .jpg image that I would like to convert to Python array, because I implemented treatment routines handling plain Python arrays.

It seems that PIL images support conversion to numpy array, and according to the documentation I have written this:

from PIL import Image im = Image.open("D:\Prototype\Bikesgray.jpg") im.show()  print(list(np.asarray(im))) 

This is returning a list of numpy arrays. Also, I tried with

list([list(x) for x in np.asarray(im)]) 

which is returning nothing at all since it is failing.

How can I convert from PIL to array, or simply from numpy array to Python array?

Answer 1

I highly recommend you use the tobytes function of the Image object. After some timing checks this is much more efficient.

def jpg_image_to_array(image_path):   """   Loads JPEG image into 3D Numpy array of shape    (width, height, channels)   """   with Image.open(image_path) as image:              im_arr = np.fromstring(image.tobytes(), dtype=np.uint8)     im_arr = im_arr.reshape((image.size[1], image.size[0], 3))                                      return im_arr 

The timings I ran on my laptop show

In [76]: %timeit np.fromstring(im.tobytes(), dtype=np.uint8) 1000 loops, best of 3: 230 µs per loop  In [77]: %timeit np.array(im.getdata(), dtype=np.uint8) 10 loops, best of 3: 114 ms per loop 

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