Weird help display

[wizebt]

Please see below how the help for imfilter is displayed, I don't think the formatting characters are supposed to show as such? It might be related to Julia rather than ImageFiltering?

julia> versioninfo()
Julia Version 1.4.2
Commit 44fa15b150* (2020-05-23 18:35 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Xeon(R) E-2186M  CPU @ 2.90GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-8.0.1 (ORCJIT, skylake)
Environment:
  JULIA_NUM_THREADS = 6

julia> using ImageFiltering

help?> imfilter
search: imfilter imfilter! ImageFiltering

  imfilter([T], img, kernel, [border="replicate"], [alg]) --> imgfilt
  imfilter([r], img, kernel, [border="replicate"], [alg]) --> imgfilt
  imfilter(r, T, img, kernel, [border="replicate"], [alg]) --> imgfilt

  Filter a one, two or multidimensional array img with a kernel by computing
  their correlation.

  Details
  ≡≡≡≡≡≡≡≡≡

  The term filtering emerges in the context of a Fourier transformation of an
  image, which maps an image from its canonical spatial domain to its
  concomitant frequency domain. Manipulating an image in the frequency domain
  amounts to retaining or discarding particular frequency components—a process
  analogous to sifting or filtering [1]. Because the Fourier transform
  establishes a link between the spatial and frequency representation of an
  image, one can interpret various image manipulations in the spatial domain
  as filtering operations which accept or reject specific frequencies.

  The phrase spatial filtering is often used to emphasise that an operation
  is, at least conceptually, devised in the context of the spatial domain of
  an image. One further distinguishes between linear and non-linear spatial
  filtering. A filter is called linear if the operation performed on the
  pixels is linear, and is labeled non-linear otherwise.

  An image filter can be represented by a function

 w: \{s\in \mathbb{Z} \mid -k_1 \le s \le k_1  \} \times  \{t \in \mathbb{Z} \mid -k_2 \le t \le k_2  \}   \rightarrow \mathbb{R},

  where k_i  \in \mathbb{N} (i = 1,2). It is common to define k_1 = 2a+1 and
  k_2 = 2b + 1, where a and b are integers, which ensures that the filter
  dimensions are of odd size. Typically, k_1 equals k_2 and so, dropping the
  subscripts, one speaks of a k \times k filter. Since the domain of the
  filter represents a grid of spatial coordinates, the filter is often called
  a mask and is visualized as a grid. For example, a 3 \times 3 mask can be
  potrayed as follows:

\scriptsize
\begin{matrix}
\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(-1,-1) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}

&

\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(-1,0) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}
 &
\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(-1,1) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}
\\
\\
\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(0,-1) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}

&

\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(0,0) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}
 &
\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(0,1) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}
\\
\\
\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(1,-1) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}

&

\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(1,0) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}
 &
\boxed{
\begin{matrix}
\phantom{w(-9,-9)} \\
w(1,1) \\
\phantom{w(-9,-9)} \\
\end{matrix}
}
\end{matrix}.

  The values of w(s,t) are referred to as filter coefficients.

  Discrete convolution versus correlation
  =========================================

  There are two fundamental and closely related operations that one regularly
  performs on an image with a filter. The operations are called discrete
  correlation and convolution.

  The correlation operation, denoted by the symbol \star, is given in two
  dimensions by the expression

\begin{aligned}
g(x,y) = w(x,y) \star f(x,y) = \sum_{s = -a}^{a} \sum_{t=-b}^{b} w(s,t) f(x+s, y+t),
\end{aligned}

  whereas the comparable convolution operation, denoted by the symbol \ast, is
  given in two dimensions by

\begin{aligned}
h(x,y) = w(x,y) \ast f(x,y) = \sum_{s = -a}^{a} \sum_{t=-b}^{b} w(s,t) f(x-s, y-t).
\end{aligned}

  Since a digital image is of finite extent, both of these operations are
  undefined at the borders of the image. In particular, for an image of size M
  \times N, the function f(x \pm s, y \pm t) is only defined for 1 \le x \pm s
  \le N and 1 \le y \pm t \le M. In practice one addresses this problem by
  artificially expanding the domain of the image. For example, one can pad the
  image with zeros. Other padding strategies are possible, and they are
  discussed in more detail in the Options section of this documentation.

  One-dimensional illustration
  ==============================

  The difference between correlation and convolution is best understood with
  recourse to a one-dimensional example adapted from [1]. Suppose that a
  filter w:\{-1,0,1\}\rightarrow \mathbb{R} has coefficients

\begin{matrix}
\boxed{1} & \boxed{2} & \boxed{3}
\end{matrix}.

  Consider a discrete unit impulse function f: \{x \in \mathbb{Z} \mid 1 \le x
  \le 7  \} \rightarrow \{0,1\} that has been padded with zeros. The function
  can be visualised as an image

\boxed{
\begin{matrix}
0 & \boxed{0} & \boxed{0} & \boxed{0} & \boxed{1} & \boxed{0} & \boxed{0} & \boxed{0} & 0
\end{matrix}}.

  The correlation operation can be interpreted as sliding w along the image
  and computing the sum of products at each location. For example,

\begin{matrix}
0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\
1 & 2 & 3  &  & & & & & \\
& 1 & 2 & 3  &  & & & &  \\
& & 1 & 2 & 3  &  & & &  \\
& & & 1 & 2 & 3  &  & &  \\
& & & & 1 & 2 & 3  &  &  \\
& & & & & 1 & 2 & 3  &  \\
& & & & & & 1 & 2 & 3,
\end{matrix}

  yields the output g: \{x \in \mathbb{Z} \mid 1 \le x \le 7  \} \rightarrow
  \mathbb{R}, which when visualized as a digital image, is equal to

\boxed{
\begin{matrix}
\boxed{0} & \boxed{0} & \boxed{3} & \boxed{2} & \boxed{1} & \boxed{0} & \boxed{0}
\end{matrix}}.

  The interpretation of the convolution operation is analogous to correlation,
  except that the filter w has been rotated by 180 degrees. In particular,

\begin{matrix}
0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\
3 & 2 & 1  &  & & & & & \\
& 3 & 2 & 1  &  & & & &  \\
& & 3 & 2 & 1  &  & & &  \\
& & & 3 & 2 & 1  &  & &  \\
& & & & 3 & 2 & 1  &  &  \\
& & & & & 3 & 2 & 1  &  \\
& & & & & & 3 & 2 & 1,
\end{matrix}

  yields the output h: \{x \in \mathbb{Z} \mid 1 \le x \le 7  \} \rightarrow
  \mathbb{R} equal to

\boxed{
\begin{matrix}
\boxed{0} & \boxed{0} & \boxed{1} & \boxed{2} & \boxed{3} & \boxed{0} & \boxed{0}
\end{matrix}}.

  Instead of rotating the filter mask, one could instead rotate f and still
  obtained the same convolution result. In fact, the conventional notation for
  convolution indicates that f is flipped and not w. If w is symmetric, then
  convolution and correlation give the same outcome.

  Two-dimensional illustration
  ––––––––––––––––––––––––––––––

  For a two-dimensional example, suppose the filter w:\{-1, 0 ,1\} \times 
  \{-1,0,1\} \rightarrow \mathbb{R} has coefficients

 \begin{matrix}
 \boxed{1} & \boxed{2} & \boxed{3} \\ \\
 \boxed{4} & \boxed{5} & \boxed{6} \\ \\
 \boxed{7} & \boxed{8} & \boxed{9}
 \end{matrix},

  and consider a two-dimensional discrete unit impulse function

 f:\{x \in \mathbb{Z} \mid 1 \le x \le 7  \} \times  \{y \in \mathbb{Z} \mid 1 \le y \le 7  \}\rightarrow \{ 0,1\}

  that has been padded with zeros:

 \boxed{
 \begin{matrix}
   0 &        0  &        0  &        0   &        0  &        0  &   0  \\ \\
   0 & \boxed{0} & \boxed{0} & \boxed{0}  & \boxed{0} & \boxed{0} &   0  \\ \\
   0 & \boxed{0} & \boxed{0} & \boxed{0}  & \boxed{0} & \boxed{0} &   0 \\ \\
   0 & \boxed{0} & \boxed{0} & \boxed{1}  & \boxed{0} & \boxed{0} &   0 \\ \\
   0 & \boxed{0} & \boxed{0} & \boxed{0}  & \boxed{0} & \boxed{0} &   0 \\ \\
   0 & \boxed{0} & \boxed{0} & \boxed{0}  & \boxed{0} & \boxed{0} &   0 \\ \\
   0 &        0  &        0  &        0   &        0  &        0  &   0
 \end{matrix}}.

  The correlation operation w(x,y) \star f(x,y) yields the output

 \boxed{
 \begin{matrix}
 \boxed{0} & \boxed{0}  & \boxed{0} & \boxed{0} & \boxed{0} \\ \\
 \boxed{0} &  \boxed{9} & \boxed{8} & \boxed{7} & \boxed{0} \\ \\
 \boxed{0} &  \boxed{6} & \boxed{5} & \boxed{4} & \boxed{0} \\ \\
 \boxed{0} &  \boxed{3} & \boxed{2} & \boxed{1} & \boxed{0} \\ \\
 \boxed{0} & \boxed{0}  & \boxed{0} & \boxed{0} & \boxed{0}
 \end{matrix}},

  whereas the convolution operation w(x,y) \ast f(x,y) produces

 \boxed{
 \begin{matrix}
 \boxed{0} & \boxed{0} & \boxed{0} & \boxed{0} & \boxed{0} \\ \\
 \boxed{0} & \boxed{1} & \boxed{2} & \boxed{3} & \boxed{0}\\ \\
 \boxed{0} & \boxed{4} & \boxed{5} & \boxed{6} & \boxed{0} \\ \\
 \boxed{0} & \boxed{7} & \boxed{8} & \boxed{9} & \boxed{0} \\ \\
 \boxed{0} & \boxed{0} & \boxed{0} & \boxed{0} & \boxed{0}
 \end{matrix}}.

  Discrete convolution and correlation as matrix multiplication
  ===============================================================

  Discrete convolution and correlation operations can also be formulated as a
  matrix multiplication, where one of the inputs is converted to a Toeplitz
  (https://en.wikipedia.org/wiki/Toeplitz_matrix) matrix, and the other is
  represented as a column vector. For example, consider a function f:\{x \in
  \mathbb{N} \mid 1 \le x \le M \} \rightarrow \mathbb{R} and a filter w: \{s
  \in \mathbb{N} \mid  -k_1 \le s \le k_1  \} \rightarrow \mathbb{R}. Then the
  matrix multiplication

\begin{bmatrix}
w(-k_1)     &  0        & \ldots    & 0        & 0          \\
\vdots  & w(-k_1)   & \ldots    & \vdots  & 0           \\
w(k_1)      & \vdots   & \ldots & 0        & \vdots    \\
0           & w(k_1)    & \ldots   & w(-k_1)  & 0           \\
0           & 0         & \ldots    & \vdots  & w(-k_1) \\
\vdots     & \vdots & \ldots    & w(k_1)   & \vdots \\
0           & 0         & 0         & 0        & w(k_1)
\end{bmatrix}
\begin{bmatrix}
f(1) \\
f(2) \\
f(3) \\
\vdots \\
f(M)
\end{bmatrix}

  is equivalent to the convolution w(s) \ast f(x) assuming that the border of
  f(x) has been padded with zeros.

  To represent multidimensional convolution as matrix multiplication one
  reshapes the multidimensional arrays into column vectors and proceeds in an
  analogous manner. Naturally, the result of the matrix multiplication will
  need to be reshaped into an appropriate multidimensional array.

  Options
  ≡≡≡≡≡≡≡≡≡

  The following subsections describe valid options for the function arguments
  in more detail.

  Choices for r
  ===============

  You can dispatch to different implementations by passing in a resource r as
  defined by the ComputationalResources
  (https://github.com/timholy/ComputationalResources.jl) package. For example,

      imfilter(ArrayFireLibs(), img, kernel)

  would request that the computation be performed on the GPU using the
  ArrayFire libraries.

  Choices for T
  ===============

  Optionally, you can control the element type of the output image by passing
  in a type T as the first argument.

  Choices for img
  =================

  You can specify a one, two or multidimensional array defining your image.

  Choices for kernel
  ====================

  The kernel[0,0,..] parameter corresponds to the origin (zero displacement)
  of the kernel; you can use centered to place the origin at the array center,
  or use the OffsetArrays package to set kernel's indices manually. For
  example, to filter with a random centered 3x3 kernel, you could use either
  of the following:

  kernel = centered(rand(3,3))
  kernel = OffsetArray(rand(3,3), -1:1, -1:1)

  The kernel parameter can be specified as an array or as a "factored kernel",
  a tuple (filt1, filt2, ...) of filters to apply along each axis of the
  image. In cases where you know your kernel is separable, this format can
  speed processing. Each of these should have the same dimensionality as the
  image itself, and be shaped in a manner that indicates the filtering axis,
  e.g., a 3x1 filter for filtering the first dimension and a 1x3 filter for
  filtering the second dimension. In two dimensions, any kernel passed as a
  single matrix is checked for separability; if you want to eliminate that
  check, pass the kernel as a single-element tuple, (kernel,).

  Choices for border
  ====================

  At the image edge, border is used to specify the padding which will be used
  to extrapolate the image beyond its original bounds. As an indicative
  example of each option the results of the padding are illustrated on an
  image consisting of a row of six pixels which are specified alphabetically:
  \boxed{a \, b \, c \, d \, e \, f}. We show the effects of padding only on
  the left and right border, but analogous consequences hold for the top and
  bottom border.

  "replicate" (default)
  –––––––––––––––––––––––

  The border pixels extend beyond the image boundaries.

\boxed{
\begin{array}{l|c|r}
  a\, a\, a\, a  &  a \, b \, c \, d \, e \, f & f \, f \, f \, f
\end{array}
}

  See also: Pad, padarray, Inner, NA and NoPad

  "circular"
  ––––––––––––

  The border pixels wrap around. For instance, indexing beyond the left border
  returns values starting from the right border.

\boxed{
\begin{array}{l|c|r}
  c\, d\, e\, f  &  a \, b \, c \, d \, e \, f & a \, b \, c \, d
\end{array}
}

  See also: Pad, padarray, Inner, NA and NoPad

  "reflect"
  –––––––––––

  The border pixels reflect relative to a position between pixels. That is,
  the border pixel is omitted when mirroring.

\boxed{
\begin{array}{l|c|r}
  e\, d\, c\, b  &  a \, b \, c \, d \, e \, f & e \, d \, c \, b
\end{array}
}

  See also: Pad, padarray, Inner, NA and NoPad

  "symmetric"
  –––––––––––––

  The border pixels reflect relative to the edge itself.

\boxed{
\begin{array}{l|c|r}
  d\, c\, b\, a  &  a \, b \, c \, d \, e \, f & f \, e \, d \, c
\end{array}
}

  See also: Pad, padarray, Inner, NA and NoPad

  Fill(m)
  –––––––––

  The border pixels are filled with a specified value m.

\boxed{
\begin{array}{l|c|r}
  m\, m\, m\, m  &  a \, b \, c \, d \, e \, f & m \, m \, m \, m
\end{array}
}

  See also: Pad, padarray, Inner, NA and NoPad

  Inner()
  –––––––––

  Indicate that edges are to be discarded in filtering, only the interior of
  the result is to be returned.

  See also: Pad, padarray, Inner, NA and NoPad

  NA()
  ––––––

  Choose filtering using "NA" (Not Available) boundary conditions. This is
  most appropriate for filters that have only positive weights, such as
  blurring filters.

  See also: Pad, padarray, Inner, NA and NoPad

  Choices for alg
  =================

  The alg parameter allows you to choose the particular algorithm: FIR()
  (finite impulse response, aka traditional digital filtering) or FFT()
  (Fourier-based filtering). If no choice is specified, one will be chosen
  based on the size of the image and kernel in a way that strives to deliver
  good performance. Alternatively you can use a custom filter type, like
  KernelFactors.IIRGaussian.

  Examples
  ≡≡≡≡≡≡≡≡≡≡

  The following subsections highlight some common use cases.

  Convolution versus correlation
  ================================

  # Create a two-dimensional discrete unit impulse function.
  f = fill(0,(9,9));
  f[5,5] = 1;

  # Specify a filter coefficient mask and set the center of the mask as the origin.
  w = centered([1 2 3; 4 5 6 ; 7 8 9]);

  #=
   The default operation of `imfilter` is correlation.  By reflecting `w` we
   compute the convolution of `f` and `w`.  `Fill(0,w)` indicates that we wish to
   pad the border of `f` with zeros. The amount of padding is automatically
   determined by considering the length of w.
  =#
  correlation = imfilter(f,w,Fill(0,w))
  convolution = imfilter(f,reflect(w),Fill(0,w))

  Miscellaneous border padding options
  ======================================

  # Example function values f, and filter coefficients w.
  f = reshape(1.0:81.0,9,9)
  w = centered(reshape(1.0:9.0,3,3))

  # You can designate the type of padding by specifying an appropriate string.
  imfilter(f,w,"replicate")
  imfilter(f,w,"circular")
  imfilter(f,w,"symmetric")
  imfilter(f,w,"reflect")

  # Alternatively, you can explicitly use the Pad type to designate the padding style.
  imfilter(f,w,Pad(:replicate))
  imfilter(f,w,Pad(:circular))
  imfilter(f,w,Pad(:symmetric))
  imfilter(f,w,Pad(:reflect))

  # If you want to pad with a specific value then use the Fill type.
  imfilter(f,w,Fill(0,w))
  imfilter(f,w,Fill(1,w))
  imfilter(f,w,Fill(-1,w))

  #=
    Specify 'Inner()' if you want to retrieve the interior sub-array of f for which
    the filtering operation is defined without padding.
  =#
  imfilter(f,w,Inner())

  References
  ≡≡≡≡≡≡≡≡≡≡≡≡

    1.   R. C. Gonzalez and R. E. Woods. Digital Image Processing (3rd
        Edition). Upper Saddle River, NJ, USA: Prentice-Hall, 2006.

  See also: imfilter!, centered, padarray, Pad, Fill, Inner,
  KernelFactors.IIRGaussian.

julia> 

[stillyslalom]

You're just seeing raw LaTeX, which is a consequence of pre-1.5 versions of Julia only allowing one docstring per method (see #153). Given a binary choice between brevity and completeness, the docs currently favor the latter, but once v1.5 is live, both approaches can be accommodated.