&'
```
Kind regards, Niels
---
### Author:  [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [November 14, 2018, 2:28pm UTC](https://discourse.itk.org/t/new-for-itk-5-0-indexrange-zerobasedindexrange-imageregionindexrange/1412/4 "2018-11-14T14:28:26Z")
This looks really great!
Do we have any filters that could converted to use this new iterator?
It would be good to come to some kind of recommendation for best practice for performance and style for this type of loop.
I also feel compelled to give a **strong word of caution** about the ZeroBasedIndexRange this strategy is not suitable for using in **most** ITK filters. Yes, it will work most of the time but it wonât work all of the time. Filters are expected to work with images or regions that donât have a zero starting index unless they override the `VerifyInputInformation` with a check. Non-zero based images or regions can occur with streaming, or as a result of filters like the `ExtractImageFilter`. These complicated features and situations are not well tested in ITK, but I have encountered and fixed them many times.
---
### Author:  [@Niels\_Dekker](https://discourse.itk.org/u/Niels_Dekker)
#### Post date: [November 14, 2018, 3:48pm UTC](https://discourse.itk.org/t/new-for-itk-5-0-indexrange-zerobasedindexrange-imageregionindexrange/1412/5 "2018-11-14T15:48:55Z")
Actually my first use case was to ease comparing the âold-schoolâ ITK neighborhood iterators with the new `ShapedImageNeighborhoodRange`, when iterating on an image region.
Old-school ITK neighborhood iteration:
```
neighborhoodIterator.GoToBegin();
while (!neighborhoodIterator.IsAtEnd())
{
for (itk::SizeValueType i = 0; i < numberOfNeigbors; ++i)
{
auto neighbor = neighborhoodIterator.GetPixel(i);
// Process neighbor pixel here...
}
++neighborhoodIterator;
}
```
And the corresponding iteration when using ShapedImageNeighborhoodRange + IndexRange:
```
for (const auto& index : indexRange)
{
shapedImageNeighborhoodRange.SetLocation(index);
for (PixelType neighbor : shapedImageNeighborhoodRange)
{
// Process neighbor pixel here...
}
}
```
So IndexRange makes it easier to interchange between âold-schoolâ and range-based neighborhood iteration, and it also eases comparing both the performance and the result, for testing purposes.
---
### Author:  [@matt.mccormick](https://discourse.itk.org/u/matt.mccormick)
#### Post date: [November 14, 2018, 7:27pm UTC](https://discourse.itk.org/t/new-for-itk-5-0-indexrange-zerobasedindexrange-imageregionindexrange/1412/6 "2018-11-14T19:27:38Z")
> [@Niels\_Dekker](#):
>
> `itk::Experimental::IndexRange` template class
This is awesome. đ
> [@Niels\_Dekker](#):
>
> ```auto
> for (const auto& index : indexRange)
> {
> shapedImageNeighborhoodRange.SetLocation(index);
>
> for (PixelType neighbor : shapedImageNeighborhoodRange)
> {
> // Process neighbor pixel here...
> }
> }
>
> ```
>
> So IndexRange makes it easier to interchange between âold-schoolâ and range-based neighborhood iteration, and it also eases comparing both the performance and the result, for testing purposes.
How do you think a class would be designed to works on an `itk::Image`, but does not need to iterate over the neighborhood, i.e. `*it` is the pixel value?
---
### Author:  [@Niels\_Dekker](https://discourse.itk.org/u/Niels_Dekker)
#### Post date: [November 15, 2018, 9:50am UTC](https://discourse.itk.org/t/new-for-itk-5-0-indexrange-zerobasedindexrange-imageregionindexrange/1412/7 "2018-11-15T09:50:50Z")
> [@matt.mccormick](#):
>
> How do you think a class would be designed to works on an `itk::Image` , but does not need to iterate over the neighborhood, i.e. `*it` is the pixel value?
`itk::Experimental::IndexRange` does already support iterating on an `itk::Image` to retrieve and modify its pixel values, for example:
```
for (const auto& index : indexRange)
{
auto pixelValue = image1.GetPixel(index);
image2.SetPixel(index, pixelValue);
}
```
Unfortunately `itk::Image::GetPixel` and `itk::Image::SetPixel` may not be superfast, because they have to compute the offset value into the image buffer.
---
### Author:  [@Niels\_Dekker](https://discourse.itk.org/u/Niels_Dekker)
#### Post date: [November 20, 2018, 8:04pm UTC](https://discourse.itk.org/t/new-for-itk-5-0-indexrange-zerobasedindexrange-imageregionindexrange/1412/8 "2018-11-20T20:04:25Z")
> [@matt.mccormick](#):
>
> How do you think a class would be designed to works on an `itk::Image` , but does not need to iterate over the neighborhood, i.e. `*it` is the pixel value?
Still very much _Work In Progress_: This `itk::Experimental::ImageRange` should support range-based iteration on the pixels on an `itk::Image`: [https://github.com/N-Dekker/ITK/tree/ImageRange](https://github.com/N-Dekker/ITK/tree/ImageRange) Please tell me what you think!
Initial commit: [WIP: Added ImageRange for itk::Image iteration. · N-Dekker/ITK@e1dd5ab · GitHub](https://github.com/N-Dekker/ITK/commit/e1dd5ab95bb8c2e4a181c6abd2d090a61249e729)
---
### Author:  [@matt.mccormick](https://discourse.itk.org/u/matt.mccormick)
#### Post date: [November 20, 2018, 8:11pm UTC](https://discourse.itk.org/t/new-for-itk-5-0-indexrange-zerobasedindexrange-imageregionindexrange/1412/9 "2018-11-20T20:11:15Z")
Beautiful @Niels_Dekker!
```auto
ImageRange range{ *image };
for (auto&& pixel : range)
{
pixel = pixel + 42;
}
```
`for_each`, `std::inner_product` tested â extremely exciting!!