How do I convert a numpy array to and display an image

Question

I have created an array thusly   import numpy as np data   np zeros   512 512 3   dtype np uint8  data 256 256     255 0 0    What I want this to do is display a single red dot in the center of a 512x512 image   At least to begin with    I think I can figure out the rest from there

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this could be a possible code solution  from skimage import io import numpy as np data np random randn 5 2  io imshow data

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Using pillow s fromarray  for example   from PIL import Image from numpy import    im   array Image open  image jpg    Image fromarray im  show

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The Python Imaging Library can display images using Numpy arrays   Take a look at this page for sample code    Convert Between Numerical Arrays and PIL Image Objects   EDIT   As the note on the bottom of that page says  you should check the latest release notes which make this much simpler   http   effbot org zone pil-changes-116 htm

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You could use PIL to create  and display  an image   from PIL import Image import numpy as np  w  h   512  512 data   np zeros  h  w  3   dtype np uint8  data 0 256  0 256     255  0  0    red patch in upper left img   Image fromarray data   RGB   img save  my png   img show

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import numpy as np from keras preprocessing image import array to img img   np zeros  525 525 3   np uint8  b array to img img  b

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The following should work   from matplotlib import pyplot as plt plt imshow data  interpolation  nearest   plt show     If you are using Jupyter notebook lab  use this inline command before importing matplotlib    matplotlib inline

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Supplement for doing so with matplotlib  I found it handy doing computer vision tasks   Let s say you got data with dtype   int32  from matplotlib import pyplot as plot import numpy as np  fig   plot figure   ax   fig add subplot 1  1  1    make sure your data is in H W C  otherwise you can change it by   data   data transpose            data   np zeros  512 512 3   dtype np int32  data 256 256     255 0 0  ax imshow data astype np uint8

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Using pygame  you can open a window  get the surface as an array of pixels  and manipulate as you want from there  You ll need to copy your numpy array into the surface array  however  which will be much slower than doing actual graphics operations on the pygame surfaces themselves

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How to show images stored in numpy array with example  works in Jupyter notebook  I know there are simpler answers but this one will give you understanding of how images are actually drawn from a numpy array  Load example from sklearn datasets import load digits digits   load digits   digits images shape    this will give you  1797  8  8   1797 images  each 8 x 8 in size  Display array of one image digits images 0  array    0    0    5   13    9    1    0    0             0    0   13   15   10   15    5    0             0    3   15    2    0   11    8    0             0    4   12    0    0    8    8    0             0    5    8    0    0    9    8    0             0    4   11    0    1   12    7    0             0    2   14    5   10   12    0    0             0    0    6   13   10    0    0    0      Create empty 10 x 10 subplots for visualizing 100 images import matplotlib pyplot as plt fig  axes   plt subplots 10 10  figsize  8 8    Plotting 100 images for i ax in enumerate axes flat       ax imshow digits images i    Result   What does axes flat do  It creates a numpy enumerator so you can iterate over axis in order to draw objects on them  Example  import numpy as np x   np arange 6  reshape 2 3  x flat for item in  x flat       print  item  end

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Shortest path is to use scipy  like this   from scipy misc import toimage toimage data  show     This requires PIL or Pillow to be installed as well   A similar approach also requiring PIL or Pillow but which may invoke a different viewer is   from scipy misc import imshow imshow data

[python] How do I convert a numpy array to (and display) an image?

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