Add two

Author: joa-quim

documentation/all_docs_ref/all_refs.md

@@ -64,10 +64,9 @@ its use requires resorting to the \myreflink{Monolithic} mode.
 |  |  |  |  |  |  |  |  |
 |:-----|:----|:----|:----|:----|:----|:----|:----|
 | \myreflink{binarize} | \myreflink{bwhitmiss} | \myreflink{bwperim} | \myreflink{bwskell} | \myreflink{fillsinks} | \myreflink{imbothat} | \myreflink{imclose} | \myreflink{imcomplement} |
-| \myreflink{imdilate} | \myreflink{imerode} | \myreflink{imfill} | \myreflink{imhdome} | \myreflink{imhmin} | \myreflink{imhmax} | \myreflink{immorphgrad} | \myreflink{imopen} |
-| \myreflink{imreconstruct} | \myreflink{imrankfilter} | \myreflink{imsegment} | \myreflink{imtophat} | \myreflink{isodata} | \myreflink{padarray} | \myreflink{strel} | \myreflink{rgb2gray} |
-| \myreflink{rgb2lab} | \myreflink{rgb2ycbcr} |  |  |  |  |  |  |
-
+| \myreflink{imdilate} | \myreflink{imerode} | \myreflink{imfill} | \myreflink{imfilter} | \myreflink{imhdome} | \myreflink{imhmin} | \myreflink{imhmax} | \myreflink{immorphgrad} |
+| \myreflink{imopen} | \myreflink{imrankfilter} | \myreflink{imreconstruct} | \myreflink{imsegment} | \myreflink{imsobel} | \myreflink{imtophat} | \myreflink{isodata} | \myreflink{padarray} |
+| \myreflink{strel} | \myreflink{rgb2gray} | \myreflink{rgb2lab} | \myreflink{rgb2ycbcr} |  |  |  |  |
 
 ## GDAL utility functions
 

documentation/utilities/imfill.md

@@ -36,7 +36,7 @@ Example from Matlab imfill.
 ```julia
 using GMT
 
-I = gdalread(GMT.TESTSDIR * "assets/coins.jpg");
+I = gdalread(TESTSDIR * "assets/coins.jpg");
 Ibw1 = binarize(I);
 Ibw2 = imfill(Ibw1);
 grdimage(I, figsize=5)

documentation/utilities/imfilter.md

@@ -0,0 +1,39 @@
+# imfilter
+
+```julia
+J = imfilter(I::GMTimage, kernel::Matrix{<:Real}; normalize::Int=1)::GMTimage
+```
+
+*keywords: GMT, Julia, fill convolution filtering*
+
+### Args
+- `I::GMTimage`: Input image. This can be a RGB or grayscale image.
+- `kernel::Matrix{<:Real}`: The filter kernel MxN matrix.
+
+### Kwargs
+- `normalize::Int=1`: Normalize the filter to unit sum. This is the default, unless ``sum(kernel) == 0``,
+   case in which we change it to 0.
+
+### Returns
+A new \myreflink{GMTimage} of the same type as `I` with the filtered image.
+
+Example
+-------
+
+Apply an 3x3 Mean Removal filter to the image "moon.png".
+
+\begin{examplefig}{}
+```julia
+using GMT
+
+I = gmtread(TESTSDIR * "assets/moon.png");
+J = imfilter(I, [-1 -1 -1; -1 9 -1; -1 -1 -1]);
+grdimage(I, figsize=5)
+grdimage!(J, figsize=5, xshift=5, show=true)
+```
+\end{examplefig}
+
+See Also
+--------
+
+\myreflink{imfill}, \myreflink{bwskell}, \myreflink{imerode}, \myreflink{imsobel}

documentation/utilities/imsobel.md

@@ -0,0 +1,49 @@
+# imsobel
+
+```julia
+J = imsobel(I::GMTimage{<:UInt8, 2}; direction::Int=2)::GMTimage
+```
+
+*keywords: GMT, Julia, Sobel filter*
+
+Sobel edge detecting filter.
+
+Returns a binary \myreflink{GMTimage} containing 1s where the function finds edges in the grayscale or binary image I and 0s elsewhere.
+
+### Args
+- `I::GMTimage`: Input grayscale image.
+
+### Kwargs
+- `direction::Int=2`: Orientation flag: `0` means detect horizontal edges, `1` means vertical and `2` means all edges.
+
+### Returns
+- A new \myreflink{GMTimage} grayscale image `I` with the edge detection, edges are brighter.
+
+Example
+-------
+
+Let us vectorize the rice grains in the image "rice.png". The result is not perfect because
+the grains in the image's edge are not closed and therefore not filled. And those get poligonized
+twice (in and outside) making the red lines look thicker (but they are not, they are just doubled).
+
+\begin{examplefig}{}
+```julia
+using GMT
+
+I = gmtread(TESTSDIR * "assets/rice.png");
+J = imsobel(I);
+BW = binarize(J);
+BW = bwskell(BW);	# Skeletize to get a better approximation of the shapes.
+BW = imfill(BW);	# Fill to avoid "double" vectorization (outside and inside grain outline)
+D = polygonize(BW);
+grdimage(I, figsize=5)
+grdimage!(J, figsize=5, xshift=5.05)
+grdimage!(BW, figsize=5, xshift=-5.05, yshift=-5.05)
+grdimage!(I, figsize=5, xshift=5.05, plot=(data=D, lc=:red), show=true)
+```
+\end{examplefig}
+
+See Also
+--------
+
+\myreflink{imfill}, \myreflink{bwskell}, \myreflink{imerode}, \myreflink{imfilter}