[vtkusers] Integer overflow in vtkImageAccumulate

[Bill Lorensen]

Gib and David,

I am working on a gerrit patch to address Gib's problem. I add you
guys to the reviewer list once I complete it.

Bill

On Tue, Oct 7, 2014 at 8:23 AM, David Gobbi <david.gobbi at gmail.com> wrote:
> Hi Gib,
>
> For VTK 5.10 and later, I added a new class called vtkImageHistogram
> that uses vtkIdType for the histogram, and another class called
> vtkImageHistogramStatistics that can automatically compute
> window/level.  These new classes should work fine on large images.
>
> Perhaps vtkImageAccumulate should also use vtkIdType (or should
> have a selectable output type.)
>
>  - David
>
>
>
> On Tue, Oct 7, 2014 at 1:30 AM, Gib Bogle <g.bogle at auckland.ac.nz> wrote:
>> Hi all,
>>
>> I encountered a problem in 3DSlicer with the auto calculation of
>> window/level.  This may be a well-known issue.  For some big 3D tiffs, the
>> algorithm gives bad w/l values, i.e. < 0.  I have tracked this to
>> vtkImageAccumulate() in vtkImageAccumulate.cxx, where the histogram is
>> computed.  The problem is that the voxel counts are stored in an int array
>> (outPtr), and it's possible to have more than 2^31 voxels with the same
>> value (e.g. 0).  I admit that these are unusual tiffs - they are binary and
>> big - so it's a rather extreme case, but it seems that this is going to bite
>> others as image sizes increase.
>>
>> Cheers
>> Gib
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