--- /dev/null
+\centering
+\begin{subfigure}[t]{0.4\textwidth}
+ \centering
+ \begin{tikzpicture}[scale=1,every node/.style={minimum size=1cm},on grid]
+
+ % Note the numbers here are reversed!
+ \def\mylist{
+ {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+ {0, 0, 1, 1, 1, 1, 1, 0, 0, 0},
+ {0, 1, 1, 2, 2, 2, 1, 0, 1, 0},
+ {0, 1, 2, 2, 3, 2, 1, 1, 1, 0},
+ {0, 1, 2, 3, 3, 2, 1, 0, 1, 0},
+ {0, 1, 2, 3, 3, 2, 1, 0, 1, 0},
+ {0, 1, 2, 2, 2, 2, 1, 1, 1, 0},
+ {0, 1, 1, 1, 1, 1, 1, 1, 0, 0},
+ {0, 0, 1, 0, 0, 1, 1, 0, 0, 0},
+ {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+ }
+
+ \fill[white,fill opacity=.7] (0,0) rectangle (5,5);
+ \draw[black,very thick] (0,0) rectangle (5,5);
+ \foreach[count=\i] \row in \mylist
+ \foreach[count=\j] \pix in \row {
+ \ifnum\pix=1\fill[black!33,fill opacity=.9] (\i*.5-.5,\j*.5-.5) rectangle
+ (\i*.5,\j*.5);\fi
+ \ifnum\pix=2\fill[black!66,fill opacity=.9] (\i*.5-.5,\j*.5-.5) rectangle
+ (\i*.5,\j*.5);\fi
+ \ifnum\pix=3\fill[black,fill opacity=.9] (\i*.5-.5,\j*.5-.5) rectangle
+ (\i*.5,\j*.5);\fi
+ }
+ \draw[step=5mm, black] (0,0) grid (5,5);
+ \draw (2.25, 0.25) node {$3$};
+ \draw (2.25, 0.75) node {$2$};
+ \draw (2.25, 1.25) node {$1$};
+ \draw (2.25, 1.75) node[white] {$0$};
+ \end{tikzpicture}
+ \caption{An example gray-scale image with four different levels.}
+\end{subfigure}
+~
+\begin{subfigure}[t]{0.4\textwidth}
+ \centering
+
+ \begin{tikzpicture}[scale=.5,every node/.style={minimum size=1cm},on grid]
+
+ \def\mylist{
+ {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+ {0, 0, 1, 1, 1, 1, 1, 0, 0, 0},
+ {0, 1, 1, 2, 2, 2, 1, 0, 1, 0},
+ {0, 1, 2, 2, 3, 2, 1, 1, 1, 0},
+ {0, 1, 2, 3, 3, 2, 1, 0, 1, 0},
+ {0, 1, 2, 3, 3, 2, 1, 0, 1, 0},
+ {0, 1, 2, 2, 2, 2, 1, 1, 1, 0},
+ {0, 1, 1, 1, 1, 1, 1, 1, 0, 0},
+ {0, 0, 1, 0, 0, 1, 1, 0, 0, 0},
+ {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+ }
+
+
+ \begin{scope}[
+ yshift=0,every node/.append style={
+ yslant=0.5,xslant=-1},yslant=0.5,xslant=-1
+ ]
+ \fill[white,fill opacity=.7] (0,0) rectangle (5,5);
+ \draw[black,very thick] (0,0) rectangle (5,5);
+
+ \fill[black,fill opacity=.9] (0,0) rectangle (5,5);
+
+ \draw[step=5mm, black] (0,0) grid (5,5);
+ \end{scope}
+
+ \begin{scope}[
+ yshift=50,every node/.append style={
+ yslant=0.5,xslant=-1},yslant=0.5,xslant=-1
+ ]
+ \fill[white,fill opacity=.7] (0,0) rectangle (5,5);
+ \draw[black,very thick] (0,0) rectangle (5,5);
+
+ \foreach[count=\i] \row in \mylist
+ \foreach[count=\j] \pix in \row {
+ \ifnum\pix<1\else\fill[black,fill opacity=.9] (\i*.5-.5,\j*.5-.5) rectangle
+ (\i*.5,\j*.5);\fi
+ }
+
+ \draw[step=5mm, black] (0,0) grid (5,5);
+ \end{scope}
+
+ \begin{scope}[
+ yshift=100,every node/.append style={
+ yslant=0.5,xslant=-1},yslant=0.5,xslant=-1
+ ]
+ \fill[white,fill opacity=.7] (0,0) rectangle (5,5);
+ \draw[black,very thick] (0,0) rectangle (5,5);
+
+ \foreach[count=\i] \row in \mylist
+ \foreach[count=\j] \pix in \row {
+ \ifnum\pix<2\else\fill[black,fill opacity=.9] (\i*.5-.5,\j*.5-.5) rectangle
+ (\i*.5,\j*.5);\fi
+ }
+
+ \draw[step=5mm, black] (0,0) grid (5,5);
+ \end{scope}
+
+ \begin{scope}[
+ yshift=150,every node/.append style={
+ yslant=0.5,xslant=-1},yslant=0.5,xslant=-1
+ ]
+ \fill[white,fill opacity=.7] (0,0) rectangle (5,5);
+ \draw[black,very thick] (0,0) rectangle (5,5);
+
+ \foreach[count=\i] \row in \mylist
+ \foreach[count=\j] \pix in \row {
+ \ifnum\pix=3\fill[black,fill opacity=.9] (\i*.5-.5,\j*.5-.5) rectangle
+ (\i*.5,\j*.5);\fi
+ }
+
+ \draw[step=5mm, black] (0,0) grid (5,5);
+ \end{scope}
+
+ \tikzstyle{blopp} = [
+ rectangle,anchor=west, text width=1.8cm
+ ]
+
+ \draw[-latex,thick] (5.2,1.5) node[blopp]
+ {$u^3 = \idfun_{u \leq 3}$} to[out=180,in=-50] (4,2);
+ \draw[-latex,thick] (5.2,3.25) node[blopp]{$u^2$}
+ to[out=180,in=-50] (4,3.75);
+ \draw[-latex,thick] (5.2,5) node[blopp]{$u^1$}
+ to[out=180,in=-50] (4,5.5);
+ \draw[-latex,thick] (5.2,6.75) node[blopp]{$u^0$}
+ to[out=180,in=-50] (4,7.25);
+
+ \end{tikzpicture}
+ \caption{The thresholded images, which are in
+ $\{0,1\}^{\abs{\Omega}}$.}
+\end{subfigure}
+