Resize RGB image?

Dave Angel d at
Sat Nov 24 12:47:08 CET 2012

On 11/24/2012 06:37 AM, Dave Angel wrote:

Oops, I sent before I was done editing.  Corrections below.
> 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,

then tell us what you expected, and what it did wrong.  In this case,
you might have to supply us with a link to sample data that demonstrates
the problem.

>> 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



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