[Insight-developers] binary object and label definitions in ITK

[Gaetan Lehmann]

On Tue, 28 Feb 2006 17:25:23 +0100, Miller, James V (GE, Research)  
<millerjv at crd.ge.com> wrote:

> For binary designation:
>
> Personally, I prefer using "zero" for background and "one" for foreground
> for binary objects (as opposed to max()). 'Course, I really don't have
> a problem with any nonzero value being identified as foreground.
>
> The only drawback to using "one" for foreground is that when you write
> out the image, you may not be able to see the objects because both
> the foreground and background are in the low end of dynamic range.
>
> I understand the interest for standardizing this, as I was bit once
> when I assumed a filter was producing 0/1 for binary images but was
> producing 0/255.


I prefer zero-max than zero-one for the reason you give, but I can live  
with zero-one solution too :-)
The important things are:
- it must be documented
- try to use the same convention in all filters, without breaking the API
- the new filters must use that convention

There is some new filters contributed to the Insight Journal which are  
manipulating those notions, so we should choose a clear definition before  
integrating those new filters in ITK, and so limit inconsistencies

>
> For labels:
>
> The idea of allowing any value to be a valid label is reasonable. In
> fact, I think the watershed algorithm makes this assumption.  The
> relabel component filter currently assumes zero is the background.
> A mode could be added to this filter to treat zero as background or not.
> This would ensure backward compatibility from a results perspective.
>

agree :-)

> Jim
>
>
>
> -----Original Message-----
> From: insight-developers-bounces+millerjv=crd.ge.com at itk.org
> [mailto:insight-developers-bounces+millerjv=crd.ge.com at itk.org]On Behalf
> Of Gaetan Lehmann
> Sent: Monday, February 27, 2006 4:42 PM
> To: insight-developers at itk.org
> Subject: [Insight-developers] binary object and label definitions in ITK
>
>
>
> Hi,
>
> While talking about types usable to manipulate binary objects and labels  
> with
> Zach, we found that they don't seem to be clearly defined in ITK.
>
> For example, ConnectedComponentImageFilter consider that binary objects  
> are
> connected set of non-zero pixels, while BinaryDilateImageFilter use a  
> value
> setted by the user to manipulate the binary object.
> Also, while we can consider as label any value allowed by a type, some  
> filters
> may fail if those values are negative.
>
> I think we should clearly define those 2 notions to avoid inconsistency  
> in the
> toolkit. I would like to propose the following ones - please correct and
> comment them:
> - The binary objects are defined with a foreground value, by default
> itk::NumericTraits<PixelType>::max(), so we can manipulate several  
> objects
> (labels). If a background value is needed, by default we should have  
> always
> the same: itk::NumericTraits<PixelType>::NonnegativeMin() (or
> itk::NumericTraits<PixelType>::Zero, it just need to be chosen). That's  
> what
> BinaryDilateImageFilter does, but it would break
> ConnectedComponentImageFilter behavior.
> - labels are any values allowed by a type. If a type need to exclude some
> values, to define a background for example, the user should be able to  
> set
> those values - it would break the RelabelComponentImageFilter behavior.
>
> Comments are welcome !
>
> Gaetan



-- 
Gaëtan Lehmann
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
http://voxel.jouy.inra.fr