I use a technique like this:
NB.* nimate: systematically reduce 3D array by an nth per each of 1st 2
dimensions.
nimate=: 4 : '((1{$y)$-.x{.1)#"(<:#$y) ((#y)$-.x{.1)#y'
load 'images'
$img=. read_image 'ballmer_peak.jpg'
592 652 3
$2 nimate img
296 326 3
See http://www.xkcd.net/323/ for this image.
On Wed, Sep 10, 2008 at 10:09 AM, David Vincent-Jones
<[EMAIL PROTECTED]>wrote:
> Yes ... I want to sample every 10th. pixel, not a full resolution sample
> block.
>
> David
>
> On Wed, 2008-09-10 at 22:19 +1200, Sherlock, Ric wrote:
> > ---David Vincent-Jones wrote:
> > > Digital images are getting to be very large today so some specialized
> > > processes become very lengthy. Sometimes I need to test
> > > several sets of
> > > parameters and at full resolution it can be very tedious.
> > >
> > > Can somebody suggest a way to subset working something like this:
> > >
> > > $ bigimage
> > > 5000 4000 3
> > > sub10=: 10 subset bigimage
> > >
> > > $ subimage
> > > 500 400 3
> >
> > Can you confirm that you want to sample every 10th pixel rather than take
> a 500 by 400 pixel region from the original?
> >
> > If so then this might work?
> >
> > subset=: 3 : 0
> > 10 subset y
> > :
> > idx=. x&[EMAIL PROTECTED] x %~ 2{.$y
> > (<idx,<a:){y
> > )
> >
> > tst=: i. 50 40 3
> >
> > $10 subset tst
> > 5 4 3
> >
> > 10 subset tst
> > 0 1 2
> > 30 31 32
> > 60 61 62
> > 90 91 92
> >
> > 1200 1201 1202
> > 1230 1231 1232
> > 1260 1261 1262
> > 1290 1291 1292
> >
> > 2400 2401 2402
> > 2430 2431 2432
> > 2460 2461 2462
> > 2490 2491 2492
> >
> > 3600 3601 3602
> > 3630 3631 3632
> > 3660 3661 3662
> > 3690 3691 3692
> >
> > 4800 4801 4802
> > 4830 4831 4832
> > 4860 4861 4862
> > 4890 4891 4892
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
--
Devon McCormick, CFA
^me^ at acm.
org is my
preferred e-mail
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