Talk:Zhang-Suen thinning algorithm

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Revision as of 19:27, 15 October 2013 by Tim-brown (talk | contribs)

Could someone help explain why, in the example image the following transformation occurs (in the periods separating the R and C, and after the C):

.....    .....
.###. -> .....
.#?#.    ..#..
.....    .....

Surely the the cell labelled '?' will be culled at step 1:

- It is black with 8 neighbours
- B = 5 (2 <= 5 <= 6)
- A = 1
- At least one of P2 P4 P6 is white (P6 is white)
- At least one of P4 P6 P8 is white (P6 is white)

Why isn't it whitened at step 1?

--Tim-brown (talk) 17:33, 15 October 2013 (UTC)

I expect that there are removals of some of those surrounding cells before it gets to your '?' cell which affects the final outcome. --Paddy3118 (talk) 18:54, 15 October 2013 (UTC)
I'm considering what happens to this individual cell (not necessarily its neighbours). As far as I am concerned, the situation I describe above is the calculation for Step-1 of the first iteration. Nothing has changed (i.e. been removed) before this: all changes are stored, and applied `after` the analysis. So the step-1 rule should apply to cell '?'. And it should be blank (by my interpretation of the rules). But it ain't.

--Tim-brown (talk) 19:27, 15 October 2013 (UTC)