# KernelFactors.gaussian

**URL:** <https://discourse.julialang.org/t/kernelfactors-gaussian/12553>\
**Category:** General Usage\
**Created:** [July 21, 2018, 6:48am UTC](https://discourse.julialang.org/t/kernelfactors-gaussian/12553 "2018-07-21T06:48:44Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![microlifecc](https://avatars.discourse-cdn.com/v4/letter/m/ed655f/32.png) [@microlifecc](https://discourse.julialang.org/u/microlifecc)\
**Post date:** [July 21, 2018, 6:48am UTC](https://discourse.julialang.org/t/kernelfactors-gaussian/12553/1 "2018-07-21T06:48:44Z")

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I have a doubt.  
In KernelFactors.gaussian I am trying to create a 1D gaussian kernel to convolve an image in vertical direction only, i.e. I need the kernel to be horizontal.  
If I define the kernel as:

```julia
imfilter(img_area, KernelFactors.gaussian(5))

```

I think it is returning a 1D vertical kernel. If I do a transpose to convert to a row vector, will imfilter automatically do the convolution in the vertical direction?  
Thanks!

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**Author:** ![stillyslalom](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stillyslalom/32/45687_2.png) [@stillyslalom](https://discourse.julialang.org/u/stillyslalom)\
**Post date:** [July 21, 2018, 7:08am UTC](https://discourse.julialang.org/t/kernelfactors-gaussian/12553/2 "2018-07-21T07:08:38Z")

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This is a pretty easy question to answer on your own:

```julia
img = zeros(5,5); img[3,3] = 1
kern = KernelFactors.gaussian(0.5)
imfilter(img, kern)

```

```julia
julia> imfilter(img, g)
ERROR: ArgumentError: ImageFiltering.Pad{1}(:replicate, (2,), (2,)) lacks the proper padding sizes for an array with 2 dimensions

```

…so no. If you want to convolve in one dimension only, construct a kernel with σ = 0 in the other dimension: `kern2 = KernelFactors.gaussian((0, 0.5))`

```julia
julia> imfilter(img, kern2)
5×5 Array{Float64,2}:
 0.0 0.0 0.0 0.0 0.0        
 0.0 0.0 0.0 0.0 0.0        
 0.000263865 0.106451 0.786571 0.106451 0.000263865
 0.0 0.0 0.0 0.0 0.0        
 0.0 0.0 0.0 0.0 0.0  

```

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<div class="post-metadata">

**Author:** ![microlifecc](https://avatars.discourse-cdn.com/v4/letter/m/ed655f/32.png) [@microlifecc](https://discourse.julialang.org/u/microlifecc)\
**Post date:** [July 21, 2018, 7:12am UTC](https://discourse.julialang.org/t/kernelfactors-gaussian/12553/3 "2018-07-21T07:12:18Z")

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@stillyslalom  
Thanks a lot!