[MINC-development] -O3 breaks N3

[Andrew Janke]

On 20 April 2012 00:59, Vladimir S. FONOV <vladimir.fonov at gmail.com> wrote:
> I managed to track problem further. First, it turns out that on new
> build  volume_stats -nocache produced very different results then
> default (and consistent with old build). So, I disabled caching.
>
> On top of that, I discovered that the output of sharpen_hist changed
> significantly.

I believe you have struck exactly the same issues that galvanised me
into writing mincstats a looooong time ago. At the time the plan was
to replace all calls of volume_stats in N3 with mincstats but this
never came to fruition given EBTKS's? creative interpretation of how
to compute a histogram on a integer volume.

Unfortunately N3's histogram entropy calculation is rather dependant
on this behaviour so mincstats attempts to mimic this with
-discrete_histogram but it's not quite the same. It comes down to
EBTKS defining bins as the edge of frequency counts whereas it should
be the centers. 'man mincstats' for more on this.

Ah, history.  Still good work tracking this down.



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