Newbie to Python here so please excuse dumb suggestions, but...
Must you use pure Python and PIL?
It seems PyLibTiff was written to solve something like this.
https://code.google.com/p/pylibtiff/
Or you could perhaps load the TIFF with numpy which allows you to
load just parts of the file, down-sample in segments, then combine.
Or just use 3rd party tools (I have used gdal with very large files,
though none larger than my RAM).
-k.
On Thu, 8 Sep 2011, Craig Coleman (C) wrote:
Hi,
I have a really thorny problem.
I need to downsample a raster map that is 23622x23622 pixels to
7874x7874 pixels using the ANTIALIAS filter.
I have the following Python code:
import Image
img = Image.open(r"C:\temp\24bit_nd.tif")
nimg = img.resize((7874,7874),Image.ANTIALIAS)
As soon as the resize method is called, python crashes instantly.
I presume this is a memory allocation issue.
Is there another way of performing anti-aliasing on such a large
image (its 2.7GB uncompressed although I'm using LZW for storage).
I have tried converting the file to 8bit with a palette and this
successfully downsamples but the ANTIALIAS is not performed.
What am I doing wrong?
Craig Coleman
Technical Lead
Information Systems, Ordnance Survey
L0F2, Adanac Drive, SOUTHAMPTON, United Kingdom, SO16 0AS
Phone: +44 (0) 2380 054641
www.ordnancesurvey.co.uk <http://www.ordnancesurvey.co.uk/> |
craig.cole...@ordnancesurvey.co.uk
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