Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Tim Rentsch Newsgroups: comp.lang.c Subject: Re: filling area by color atack safety Date: Tue, 19 Mar 2024 21:19:19 -0700 Organization: A noiseless patient Spider Lines: 37 Message-ID: <86sf0lmt6g.fsf@linuxsc.com> References: <20240317144625.00002011@yahoo.com> <86y1afopik.fsf@linuxsc.com> <861q86ojfm.fsf@linuxsc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: dont-email.me; posting-host="7a780175fd21d30328a8a78d1217a04c"; logging-data="1384297"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/BDQnAG+RLruv3PvGOgds2OkqZfDsh+G4=" User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux) Cancel-Lock: sha1:jq4I2KKEyJZMujsXgtUttX8aXZY= sha1:QB4vFDinVBaLGseuSxQi/R3l/qY= Bytes: 2463 Malcolm McLean writes: > On 19/03/2024 05:54, Tim Rentsch wrote: > >> Malcolm McLean writes: >> >>> On 18/03/2024 09:30, Tim Rentsch wrote: >>> >>>> Michael S 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. > > That is the terminology in binary image processing. The pixels are > 4-connected or 8-connected depending on whether a shared corner is > considered to make the group of pixels two objects or one object. A poor choice of terminology. Side adjacent or corner and side adjacent would be better.