Resize RGB image?

Dave Angel d at
Sat Nov 24 12:37:46 CET 2012

On 11/24/2012 06:14 AM, Alasdair McAndrew wrote:
> I can resize a 2d image "im" with a command something like:
> r,c = shape(im)
> im2 = resize(im,(r//2,c//2))

You're missing at least one import there.

So how about you start by telling us what non-standard libraries you're
using, what version of python you're  using, and what OS ?  Then supply
us a working set of code, in the sense that people can see the problem
you're complaining about.

> However, resize doesn't seem to work with an RGB image:
> r,c,n = shape(im)  # returns, say 500 600 3 

Doesn't work is pretty vague.  It could mean anything from "it makes the
image too small by 1%" to "it crashes my system after reformatting my
hard disk."  If you get an error, include the entire traceback here.  If
it doesn't work in some other sense,

> I then need to take each band separately, resize it, and put them all back together with dstack:
> imr = im[:,:,0]
> img = im[:,:,1]
> imb = im[:,:,2]
> imr2 = resize(imr,(r//2,c//2))
> img2 = resize(img,(r//2,c//2))
> imb2 = resize(imb,(r//2,c//2))
> im2 = dstack((imr2,img2,imb2))
> This works fine, but seems a little clumsy.  Of course this could be done in one command:
> im2 = dstack([resize(im[:,:,i],(r//2,c//2)) for i in range(3)])
> What I want to know is: is there a version of resize which can be applied directly to multi-band images, without having to apply to each band separately?
> Thanks,
> Alasdair



More information about the Python-list mailing list