Newsgroups:   comp.lang.apl
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From:         loc@yrloc.ipsa.reuter.COM (Leigh Clayton)
Subject:      EEM replies to William Ricker
Message-ID: <1991Apr11.185839.3428@yrloc.ipsa.reuter.COM>
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Date:         11 Apr 91 17:36:01 UT

----------Forwarded from Eugene McDonnell via IPSA mailbox-----------------


no. 5092717 filed 17.20.18  wed 10 apr 1991
from eem
to   clapl

Reply to William Ricker

The histogram algorithm discussed recently does not derive from
the work reported on at APL80, but rather results from recent
developments in the J dialect. I'd be surprised if you were able
to find a copy of the APL80 proceedings, since the organizers
refused to be persuaded by my arguments and published them using
the commercial house North-Holland. I wanted them to use ACM, as
earlier and later meetings did. One of the organizers worked for
North-Holland. The proceedings cost about $100, I believe.

In any event, the histogram algorithm H referred to in the APL90
paper you cite is as follows:

H:+/((_1+min/min/M)drop iota max/max/M)jot.=,M,O take quadio is 1

where: Let M(x,y) be a digitized image, 1 le y le n,
1 le x le m, O le M(x,y) le k, where k is the maximum
grey level. The pixels are classified into classes of
'similar' values, which have the same physical behaviour
in the scene, obtained by the interactive exploration of
the numerical matrix.




-----------------------------------------------------------
loc@tmsoft.UUCP                     uunet!mnetor!tmsoft!loc
loc@yrloc.ipsa.reuter.COM                   (Leigh Clayton)
