How can I save an image with PIL

Question

I have just done some image processing using the Python image library  PIL  using a post I found earlier to perform fourier transforms of images and I can t get the save function to work  The whole code works fine but it just wont save the resulting image   from PIL import Image import numpy as np  i   Image open  C  Users User Desktop mesh bmp   i   i convert  L   a   np asarray i  b   np abs np fft rfft2 a   j   Image fromarray b  j save  C  Users User Desktop mesh trans    bmp     The error I get is the following   save handler   SAVE string upper format     unknown format     KeyError    BMP    How can I save an image with Pythons PIL

User · Accepted Answer

The error regarding the file extension has been handled, you either use BMP (without the dot) or pass the output name with the extension already. Now to handle the error you need to properly modify your data in the frequency domain to be saved as an integer image, PIL is telling you that it doesn't accept float data to save as BMP.

Here is a suggestion (with other minor modifications, like using fftshift and numpy.array instead of numpy.asarray) for doing the conversion for proper visualization:

import sys
import numpy
from PIL import Image

img = Image.open(sys.argv[1]).convert('L')

im = numpy.array(img)
fft_mag = numpy.abs(numpy.fft.fftshift(numpy.fft.fft2(im)))

visual = numpy.log(fft_mag)
visual = (visual - visual.min()) / (visual.max() - visual.min())

result = Image.fromarray((visual * 255).astype(numpy.uint8))
result.save('out.bmp')

User · Answer

You should be able to simply let PIL get the filetype from extension  i e  use   j save  C  Users User Desktop mesh trans bmp

User · Answer

Try removing the   before the  bmp  it isn t matching BMP as expected   As you can see from the error  the save handler is upper-casing the format you provided and then looking for a match in SAVE  However the corresponding key in that object is BMP  instead of  BMP    I don t know a great deal about PIL  but from some quick searching around it seems that it is a problem with the mode of the image  Changing the definition of j to   j   Image fromarray b  mode  RGB     Seemed to work for me  however note that I have very little knowledge of PIL  so I would suggest using  mmgp s solution as s he clearly knows what they are doing       For the types of mode  I used this page - hopefully one of the choices there will work for you

User · Answer

I know that this is old  but I ve found that  while using Pillow  opening the file by using open fp   w   and then saving the file will work  E g   with open fp   w   as f      result save f    fp being the file path  of course

[python] How can I save an image with PIL?

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