Bug in SURF sum_rect()

[Mimino666]

Shouldn't the lines 42 and 43 in file https://github.com/luispedro/mahotas/blob/master/mahotas/features/_surf.cpp be:

y1 = std::min<int>(y1, integral.dim(0)-1);
x1 = std::min<int>(x1, integral.dim(1)-1);

?

[luispedro]

I think you're right that those lines are wrong, though my feeling is that it should be

y1 = std::min<int>(y1 - 1, integral.dim(0)-1);
x1 = std::min<int>(x1 - 1, integral.dim(1)-1);

It needs to be y1-1 because the outward facing interface is that we are computing array[y0:y1, x0:x1], so it should be integral[y1,x1] - integral[y0,x0]. The bounds check is useless, though.

I'll check this more carefully and commit the fix.

Thanks Luis