> If I am wrong and "cut" could be used please correct me.
$ bigimage
5000 4000 3
first =. {.@, NB. first atom of any n-dim array
$ (10 10 1 ,: 1 1 1) first;.3 bigimage
500 400 3
The left argument for the tesselation is (stride ,: sub-cube size).
Since you want to sample down to the "first edgde atom", the size
of the accessed sub-cube doesn't matter much. The sample above
selects only the corner (of shape 1 1 1). The "first" processing
instead of a naive "[" identity converts that from a rank-3 singleton
cube into a scalar; all those sample scalars combine back into a
rank-3 image array.
The Dictionary entry for Cut has quite an abtract wording in order
to cater for the general, rank-n case. With your your specific
application in mind, fill in values given above for x/y/u and work
through those few sentences again. That is, see how "|1{x" and other
expressions used in the definition work out.
Martin
PS: It would be nice hear which part of the Cut entry threw you
off so far.
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