Working with images in Python

Dealing with images in a command line fashion can be approach:

using Python to do the image processing / manipulation itself
using Python to batch process the call of a third-party command (i.e. Image Magick) that will do the image manipulation
other?

Python Imaging Library (PIL or Pillow)

The PIL package or the more recent fork called Pillow seems to be a robust environement to work with images.

Start by installing Pillow package from your Anaconda prompt

conda install pillow

Once this is successfull import Pillow



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from PIL import Image

If you are downloading it from Internet, use the following command by modifying the local_loc to the folder you are interested in saving the image.



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import urllib.request
local_loc = 'C:\data\local_image.tif'
urllib.request.urlretrieve('http://folk.uio.no/sebastcc/images/Mtg01_bl1_MOAB2_s023_scaled20perc.tif', local_loc)
im = Image.open(local_loc)



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p=1



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type(p)



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type(im)



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print(im.height,im.width)



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im.mode?



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im.show()



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# split the image into individual bands
source = im.split()



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R, G, B = 0, 1, 2



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type(source)



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type(source[R])



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type(source[G])



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source[R]

The point() method can be used to translate the pixel values of an image (e.g. image contrast manipulation). In most cases, a function object expecting one argument can be passed to this method. Each pixel is processed according to that function:



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def inv_pix(pix):
    inv = 255-pix
    return inv



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source[R].point(inv_pix);



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source[G].point(inv_pix);



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source[B].point(inv_pix);



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source[G].paste



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source[G].paste



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source[R].paste(source[R].point(inv_pix))



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source[G].paste(source[G].point(inv_pix))



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source[B].paste(source[B].point(inv_pix))



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Image.merge??



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im.mode



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imnew = Image.merge(im.mode, source)



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imnew.show()



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imnew



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imnew.save('C:\data\GitHub\PythonClub\Mtg01_bl1_MOAB2_s023_scaled20perc_inverted.tif')

Much faster solution using eval method from Image module (thanks to Gergely). No need to split the channels.



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im = Image.open(t)
imfast = Image.eval(im,inv_pix)

Calling Image Magick from Python

TBD

Image Magick : http://www.imagemagick.org/script/index.php



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convert