How to convert a PIL Image into a numpy array

Question

Alright  I m toying around with converting a PIL image object back and forth to a numpy array so I can do some faster pixel by pixel transformations than PIL s PixelAccess object would allow   I ve figured out how to place the pixel information in a useful 3D numpy array by way of   pic   Image open  foo jpg   pix   numpy array pic getdata    reshape pic size 0   pic size 1   3    But I can t seem to figure out how to load it back into the PIL object after I ve done all my awesome transforms   I m aware of the putdata   method  but can t quite seem to get it to behave

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Convert Numpy to PIL image  and PIL to Numpy  import numpy as np from PIL import Image  def pilToNumpy img       return np array img   def NumpyToPil img       return Image fromarray img

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Open I as an array    gt  gt  gt  I   numpy asarray PIL Image open  test jpg      Do some stuff to I  then  convert it back to an image    gt  gt  gt  im   PIL Image fromarray numpy uint8 I     Filter numpy images with FFT  Python  If you want to do it explicitly for some reason  there are pil2array   and array2pil   functions using getdata   on this page in correlation zip

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I am using Pillow 4 1 1  the successor of PIL  in Python 3 5  The conversion between Pillow and numpy is straightforward     from PIL import Image import numpy as np im   Image open  1 jpg   im2arr   np array im    im2arr shape  height x width x channel arr2im   Image fromarray im2arr    One thing that needs noticing is that Pillow-style im is column-major while numpy-style im2arr is row-major  However  the function Image fromarray already takes this into consideration  That is  arr2im size    im size and arr2im mode    im mode in the above example     We should take care of the HxWxC data format when processing the transformed numpy arrays  e g  do the transform im2arr   np rollaxis im2arr  2  0  or im2arr   np transpose im2arr   2  0  1   into CxHxW format

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You re not saying how exactly putdata   is not behaving  I m assuming you re doing    gt  gt  gt  pic putdata a  Traceback  most recent call last     File     blablabla    PIL Image py   line 1185  in putdata     self im putdata data  scale  offset  SystemError  new style getargs format but argument is not a tuple   This is because putdata expects a sequence of tuples and you re giving it a numpy array  This   gt  gt  gt  data   list tuple pixel  for pixel in pix   gt  gt  gt  pic putdata data    will work but it is very slow    As of PIL 1 1 6  the  proper  way to convert between images and numpy arrays is simply   gt  gt  gt  pix   numpy array pic    although the resulting array is in a different format than yours  3-d array or rows columns rgb in this case    Then  after you make your changes to the array  you should be able to do either pic putdata pix  or create a new image with Image fromarray pix

User · Answer

Open I as an array    gt  gt  gt  I   numpy asarray PIL Image open  test jpg      Do some stuff to I  then  convert it back to an image    gt  gt  gt  im   PIL Image fromarray numpy uint8 I     Filter numpy images with FFT  Python  If you want to do it explicitly for some reason  there are pil2array   and array2pil   functions using getdata   on this page in correlation zip

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The example  I have used today   import PIL import numpy from PIL import Image  def resize image numpy array image  new height         convert nympy array image to PIL Image     image   Image fromarray numpy uint8 numpy array image       old width   float image size 0       old height   float image size 1       ratio   float  new height   old height      new width   int old width   ratio      image   image resize  new width  new height   PIL Image ANTIALIAS        convert PIL Image into nympy array back again     return array image

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def imshow img       img   img   2   0 5       unnormalize     npimg   img numpy       plt imshow np transpose npimg   1  2  0        plt show     You can transform the image into numpy  by parsing the image into numpy   function after squishing out the features  unnormalization

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Convert Numpy to PIL image  and PIL to Numpy  import numpy as np from PIL import Image  def pilToNumpy img       return np array img   def NumpyToPil img       return Image fromarray img

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You need to convert your image to a numpy array this way   import numpy import PIL  img   PIL Image open  foo jpg   convert  L   imgarr   numpy array img

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If your image is stored in a Blob format  i e  in a database  you can use the same technique explained by Billal Begueradj to convert your image from Blobs to a byte array   In my case  I needed my images where stored in a blob column in a db table   def select all X values conn       cur   conn cursor       cur execute  SELECT ImageData from PiecesTable           rows   cur fetchall           return rows   I then created a helper function to change my dataset into np array   X dataset   select all X values conn  imagesList   convertToByteIO np array X dataset    def convertToByteIO imagesArray                 Converts an array of images into an array of Bytes             imagesList           for i in range len imagesArray              img   Image open BytesIO imagesArray i    convert  RGB           imagesList insert i  np array img        return imagesList   After this  I was able to use the byteArrays in my Neural Network   plt imshow imagesList 0

User · Answer

def imshow img       img   img   2   0 5       unnormalize     npimg   img numpy       plt imshow np transpose npimg   1  2  0        plt show     You can transform the image into numpy  by parsing the image into numpy   function after squishing out the features  unnormalization

User · Answer

The example  I have used today   import PIL import numpy from PIL import Image  def resize image numpy array image  new height         convert nympy array image to PIL Image     image   Image fromarray numpy uint8 numpy array image       old width   float image size 0       old height   float image size 1       ratio   float  new height   old height      new width   int old width   ratio      image   image resize  new width  new height   PIL Image ANTIALIAS        convert PIL Image into nympy array back again     return array image

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You re not saying how exactly putdata   is not behaving  I m assuming you re doing    gt  gt  gt  pic putdata a  Traceback  most recent call last     File     blablabla    PIL Image py   line 1185  in putdata     self im putdata data  scale  offset  SystemError  new style getargs format but argument is not a tuple   This is because putdata expects a sequence of tuples and you re giving it a numpy array  This   gt  gt  gt  data   list tuple pixel  for pixel in pix   gt  gt  gt  pic putdata data    will work but it is very slow    As of PIL 1 1 6  the  proper  way to convert between images and numpy arrays is simply   gt  gt  gt  pix   numpy array pic    although the resulting array is in a different format than yours  3-d array or rows columns rgb in this case    Then  after you make your changes to the array  you should be able to do either pic putdata pix  or create a new image with Image fromarray pix

User · Answer

You re not saying how exactly putdata   is not behaving  I m assuming you re doing    gt  gt  gt  pic putdata a  Traceback  most recent call last     File     blablabla    PIL Image py   line 1185  in putdata     self im putdata data  scale  offset  SystemError  new style getargs format but argument is not a tuple   This is because putdata expects a sequence of tuples and you re giving it a numpy array  This   gt  gt  gt  data   list tuple pixel  for pixel in pix   gt  gt  gt  pic putdata data    will work but it is very slow    As of PIL 1 1 6  the  proper  way to convert between images and numpy arrays is simply   gt  gt  gt  pix   numpy array pic    although the resulting array is in a different format than yours  3-d array or rows columns rgb in this case    Then  after you make your changes to the array  you should be able to do either pic putdata pix  or create a new image with Image fromarray pix

User · Answer

You need to convert your image to a numpy array this way   import numpy import PIL  img   PIL Image open  foo jpg   convert  L   imgarr   numpy array img

User · Answer

You re not saying how exactly putdata   is not behaving  I m assuming you re doing    gt  gt  gt  pic putdata a  Traceback  most recent call last     File     blablabla    PIL Image py   line 1185  in putdata     self im putdata data  scale  offset  SystemError  new style getargs format but argument is not a tuple   This is because putdata expects a sequence of tuples and you re giving it a numpy array  This   gt  gt  gt  data   list tuple pixel  for pixel in pix   gt  gt  gt  pic putdata data    will work but it is very slow    As of PIL 1 1 6  the  proper  way to convert between images and numpy arrays is simply   gt  gt  gt  pix   numpy array pic    although the resulting array is in a different format than yours  3-d array or rows columns rgb in this case    Then  after you make your changes to the array  you should be able to do either pic putdata pix  or create a new image with Image fromarray pix

User · Answer

I am using Pillow 4 1 1  the successor of PIL  in Python 3 5  The conversion between Pillow and numpy is straightforward     from PIL import Image import numpy as np im   Image open  1 jpg   im2arr   np array im    im2arr shape  height x width x channel arr2im   Image fromarray im2arr    One thing that needs noticing is that Pillow-style im is column-major while numpy-style im2arr is row-major  However  the function Image fromarray already takes this into consideration  That is  arr2im size    im size and arr2im mode    im mode in the above example     We should take care of the HxWxC data format when processing the transformed numpy arrays  e g  do the transform im2arr   np rollaxis im2arr  2  0  or im2arr   np transpose im2arr   2  0  1   into CxHxW format

User · Answer

If your image is stored in a Blob format  i e  in a database  you can use the same technique explained by Billal Begueradj to convert your image from Blobs to a byte array   In my case  I needed my images where stored in a blob column in a db table   def select all X values conn       cur   conn cursor       cur execute  SELECT ImageData from PiecesTable           rows   cur fetchall           return rows   I then created a helper function to change my dataset into np array   X dataset   select all X values conn  imagesList   convertToByteIO np array X dataset    def convertToByteIO imagesArray                 Converts an array of images into an array of Bytes             imagesList           for i in range len imagesArray              img   Image open BytesIO imagesArray i    convert  RGB           imagesList insert i  np array img        return imagesList   After this  I was able to use the byteArrays in my Neural Network   plt imshow imagesList 0

[python] How to convert a PIL Image into a numpy array?

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