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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: filling area by color atack safety
Date: Mon, 18 Mar 2024 22:54:37 -0700
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Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:

> On 18/03/2024 09:30, Tim Rentsch wrote:
>
>> Michael S <already5chosen@yahoo.com> writes:
[...]
>>> Except I don't understand why it works it all.
>>> Can't fill area have sub-areas that only connected through
>>> diagonal?
>>
>> It is customary in raster graphics to count pixels as adjacent
>> only if they share an edge, not if they just share a corner.
>> Usually that gives better results;  the exceptions tend to need
>> special handling anyway and not just connecting through
>> diagonals.
>
> Though with a binary image, if the foreground is 4-connected, the
> background must therefore be 8-connected.

It might be but it doesn't have to be.

Also different terminology should be used, since 4-connected
(also N-connected, for other integer N) has a specific meaning in
graph theory, and one very different than what is meant above.