% https://alfurka.github.io/quick-tikz/
\begin{tikzpicture}[background rectangle/.style={fill=white}, show background rectangle]
  % Axis
  \draw[step=1,gray,very thin] (-5,-5) grid (5,5);

  % Pixels
  \draw[fill=lightgray,ultra thin] (-4,-4) rectangle ++(1,1);

  \foreach \y in {-3,-2}
  \foreach \x in {\y-1,\y}
  \draw[fill=lightgray,ultra thin] (\x,\y) rectangle ++(1,1);

  \draw[fill=lightgray,ultra thin] (-1,-2) rectangle ++(1,1);

  \foreach \y in {-1,0,1,2}
  \foreach \x in {\y,\y+1}
  \draw[fill=lightgray,ultra thin] (\x,\y) rectangle ++(1,1);

  % Main shape
  \draw[blue] (-4,-3.5) -- (3.5,2.5);
\end{tikzpicture}