Question

Does anyone know how to open a large imagery file using python?
I tried to open an imagery file (about 2 GB) through windows command prompt using ipython, but it crashes every time after I change image values into an array.

My laptop is window7-64bit with 4GB ram and Intel(R) Core(TM) i7-2860 QM CPU.

The error message is: python.exe has stopped working A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available

Here is my code.

import Image
import numpy as num
im=Image.open('myimage.tif')
imarray=num.array(im)

Answer 1

How much RAM do you have? You’ll need quite a bit more than 2GB of RAM to store a 2-gig image. I don’t know how efficient Image is at storing images, but a list of bytes uses four bytes of space for each element in the list, so you’ll burn more than 8GB of (virtual) memory… and a lot of patience. Edit: Since you only have 4 (or 3) GB to play with, this is almost certainly your problem.

But why are you trying to convert it to a numeric array? Use the methods of the im object returned by Image.open, as in the PIL Tutorial.

I don’t know what you’re doing with the image, but perhaps you can do it without reading the entire image in memory, or at least without converting the entire object into a numpy array. Read it bit by bit if possible to avoid blowing up your machine: Read up on python generators, and see the Image.getdata() method, which returns your image one pixel value at a time.