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

User · Accepted Answer

I think what you are looking for is   list im getdata      or  if the image is too big to load entirely into memory  so something like that   for pixel in iter im getdata         print pixel   from PIL documentation      getdata      im getdata      sequence      Returns the contents of an image as a sequence object containing pixel   values  The sequence object is flattened  so that values for line one   follow directly after the values of line zero  and so on       Note that the sequence object returned by this method is an internal   PIL data type  which only supports certain sequence operations    including iteration and basic sequence access  To convert it to an   ordinary sequence  e g  for printing   use list im getdata

User · Answer

Based on zenpoy s answer   import Image import numpy  def image2pixelarray filepath               Parameters     ----------     filepath   str         Path to an image file      Returns     -------     list         A list of lists which make it simple to access the greyscale value by         im y  x              im   Image open filepath  convert  L        width  height    im size     greyscale map   list im getdata        greyscale map   numpy array greyscale map      greyscale map   greyscale map reshape  height  width       return greyscale map

User · Answer

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   s per loop  In  77    timeit np array im getdata    dtype np uint8  10 loops  best of 3  114 ms per loop

User · Answer

I use numpy fromiter to invert a 8-greyscale bitmap  yet no signs of side-effects  import Image import numpy as np  im   Image load  foo jpg   im   im convert  L    arr   np fromiter iter im getdata     np uint8  arr resize im height  im width   arr    0xFF    invert inverted im   Image fromarray arr  mode  L   inverted im show

[python] PIL image to array (numpy array to array) - Python

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