[Tex/LaTex] Beamer Highlighting some part of an image and hiding remaining part

beamergraphicstikz-pgf

I want to highlight some part of an image and hiding the remaining part. My minimum working example is below. Any help will be highly appreciated. Thanks

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\begin{document}

\begin{frame}

\begin{tikzpicture}
\node[anchor = south west, inner sep = 0] (A) at (0, 0) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio]{Effile.jpeg}};

\draw[red, ultra thick] (1.05, 5.1) rectangle (2.49, 4.3);

\fill [draw = none, fill = white, fill opacity = 1.0] (1.05, 5.1) -- (2.49, 5.1) -- (2.49, 1.05) -- cycle;

\end{tikzpicture}

\end{frame}

\end{document}

Best Answer

Edit
~~With the overlay-beamer-styles library this can be done quite elegantly.~~ Apparently one does not need the overlay-beamer-styles library, because the Tikz macros work with the overlay syntax of beamer!

I include the image in the same way, but name the node image. Also, it doesn't matter where the node is placed.

\begin{tikzpicture}
    \node[anchor = south west, inner sep = 0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

Then I can define a scope that has (0,0) in the bottom left corner of image, (1,0) in the bottom right corner, (0,1) in the top left corner and (1,1) in the top right corner.

    \begin{scope}[shift={(image.south west)},x={(image.south east)},y={(image.north west)}]

Drawing a grid that scales with the image is now straightforward. This makes it easy to recognize the place of the paths needed in the next step.

        % Draw a overlaying grid to easily see where the rectangles must be, this can be commented out in the final version
        \draw foreach \xy in {0,0.1,...,1.001}{
            (\xy,0) -- node[pos=0,below]{\pgfmathprintnumber{\xy}} (\xy,1)
            (0,\xy) -- node[pos=0,left]{\pgfmathprintnumber{\xy}} (1,\xy)};

Having identified the paths of the segment I want to highlight, I can add these to my \foreach loop, which draws a big white rectangle on top of the image, excludes the path I specified, and draws an additional red rectangle around the highlighted segment. Additionally, the overlay-beamer-styles library provides the visible on={<>} key, which can be used with the counter in the \foreach.

        \foreach[count=\i] \mypath in {
            {(0.1,0.55) rectangle (0.25,0.65)},
            {(0.45,0.85) rectangle (0.6,0.95)},
            {(0.5,0.5) circle (1cm)},
            {(0.75,0.3) rectangle (0.85,0.35) (0.25,0.75) circle (1.5cm)}
        }{
            \filldraw<\i>[white,opacity=0.75,even odd rule] (0,0) rectangle (1,1) \mypath;
            \draw<\i>[red,ultra thick] \mypath;
        }

Finally close the scope and the tikzpicture.

    \end{scope}
\end{tikzpicture}

This results in:

where the grid is still visible, and the white rectangle is 'see-through', but for a final version this can be made opaque and the grid can be hidden.

Total MWE (also note that I draw the grid on top of the images and white rectangle, because otherwise it would not be very helpful):

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \begin{scope}[shift={(image.south west)},x={(image.south east)},y={(image.north west)}]

                \foreach[count=\i] \mypath in {
                    {(0.1,0.55) rectangle (0.25,0.65)},
                    {(0.45,0.85) rectangle (0.6,0.95)},
                    {(0.5,0.5) circle (1cm)},
                    {(0.75,0.3) rectangle (0.85,0.35) (0.25,0.75) circle (1.5cm)}
                }{
                    \filldraw<\i>[white,even odd rule] (0,0) rectangle (1,1) \mypath;
                    \draw<\i>[red,ultra thick] \mypath;
                }

%                 Draw a overlaying grid to easily see where the rectangles must be, this can be commented out in the final version
%                \draw foreach \xy in {0,0.1,...,1.001}{
%                    (\xy,0) -- node[pos=0,below]{\pgfmathprintnumber{\xy}} (\xy,1)
%                    (0,\xy) -- node[pos=0,left]{\pgfmathprintnumber{\xy}} (1,\xy)};
            \end{scope}

        \end{tikzpicture}
    \end{frame}
\end{document}

Edit 2
Due to the fancy example shown by @marmot in his answer, I had to add something fancy myself :)

This can be done with:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \begin{scope}[shift={(image.south west)},x={(image.south east)},y={(image.north west)}]
                \clip (0,0) rectangle (1,1);
                \foreach[count=\i] \myDim in {0,5,...,106}{
                    \begin{scope}[shift={(0.5,0.5)}]
                        \filldraw<\i>[white,opacity=1,even odd rule,] (-0.5,-0.5) rectangle (0.5,0.5) (0,1.38*\myDim mm)
                            -- ++(288:\myDim mm) -- ++(  0:\myDim mm)
                            -- ++(216:\myDim mm) -- ++(288:\myDim mm)
                            -- ++(144:\myDim mm) -- ++(216:\myDim mm)
                            -- ++( 72:\myDim mm) -- ++(144:\myDim mm)
                            -- ++(  0:\myDim mm) -- cycle;
                        \draw<\i>[red,ultra thick] (0,1.38*\myDim mm)
                            -- ++(288:\myDim mm) -- ++(  0:\myDim mm)
                            -- ++(216:\myDim mm) -- ++(288:\myDim mm)
                            -- ++(144:\myDim mm) -- ++(216:\myDim mm)
                            -- ++( 72:\myDim mm) -- ++(144:\myDim mm)
                            -- ++(  0:\myDim mm) -- cycle;
                    \end{scope}
                }
            \end{scope}

        \end{tikzpicture}
    \end{frame}
\end{document}

Edit 3
This will (probably _^(maybe)) be the last one:

Done with:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\usetikzlibrary{shapes}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0,outer sep=0.5\pgflinewidth] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \clip (image.south west) rectangle (image.north east);

            \foreach[count=\k] \myDim in {0,0.2,...,3.4}{
                \ifnum\k>1
                    \def\mypath{
                        [scale={\myDim^2}] (image.center)
                        foreach \myPhi [count=\i,evaluate=\i as \j using {0.5*mod(\i,2)+0.5}] in {0,36,...,359}{
                            \ifnum\i=1
                                   +({90+50*sqrt(\k)+\myPhi}:\j)
                                \else
                                -- +({90+50*sqrt(\k)+\myPhi}:\j)
                            \fi
                        } -- cycle
                    }
                \else
                    \def\mypath{}
                \fi

                \filldraw<\k>[white]
                    (image.south west) rectangle (image.north east) \mypath;
                \draw<\k>[red,ultra thick] \mypath;
            }

        \end{tikzpicture}
    \end{frame}
\end{document}

Edit 4
This really is the final one:

Done with the \clip command (sneakingly stolen from @marmot's answer). Also I defined a use node cs style which takes a node name as argument and makes it easier to draw in that relative coordinate system:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\usetikzlibrary{calc}

\tikzset{
    use node cs/.style={shift={(#1.south west)},x={(#1.south east)},y={(#1.north west)}}
}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0,opacity=0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \clip (image.south west) rectangle (image.north east);

            \foreach \myDim [count=\i] in{0,...,30}{
                \clip<\i>[use node cs=image] let 
                    \n1={max(\myDim,0)},
                    \n2={max(\myDim - 1,0)},
                    \n3={max(\myDim - 2,0)},
                    \n4={max(\myDim - 3,0)},
                    \n5={max(\myDim - 4,0)}
                in 
                    (0.1,0.2) circle (\n1 mm)
                    (0.6,0.4) circle (\n2 mm)
                    (0.8,0.2) circle (\n5 mm)
                    (0.5,0.3) circle (\n1 mm)
                    (0.1,0.8) circle (\n5 mm)
                    (0.4,0.9) circle (\n3 mm)
                    (0.7,0.7) circle (\n1 mm)
                    (0.2,0.5) circle (\n3 mm)
                    (0.9,0.6) circle (\n2 mm)
                    (0.9,0.8) circle (\n1 mm);
            }
            \node[anchor = south west, inner sep = 0] {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

        \end{tikzpicture}
    \end{frame}
\end{document}

Notes:

To get the images to align I shifted the drawing of the box by 0.5\pgflinewidth. So if you notice that your beamer image shifts from slide to slide, you will need to apply this shift as well.
Even with this adjustment, the second image appears to be off slightly and I don't know why. So perhaps another tweak is required.

Code:

\RequirePackage[demo]{graphicx}

\documentclass{beamer}

\usetheme{Copenhagen}
\usecolortheme{whale}
\useinnertheme{rounded}

\usepackage{tikz}

\newcounter{boxes}

\newcommand\ordbox[2]{%
  \stepcounter{boxes}
  \tikz[remember picture,overlay]{
  \node[rectangle,rounded corners,line width=2pt,draw=red,fill=pink,text height=10pt,text depth=3pt,align=left,draw opacity = 0.75, fill opacity=.75,text opacity=1] (box-\theboxes) at #2 {#1};}
}

\newcommand\tikzmark[1]{%
  \tikz[remember picture,overlay] \node (#1) {};}

\begin{document}
\begin{frame}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0] at (0,0) {\includegraphics[scale=0.2]{../images/H1D_level_5.pdf}};
\end{tikzpicture}
\end{frame}
\begin{frame}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0] (A) at (0,0) {\includegraphics[scale=0.2]{../images/H1D_level_5.pdf}};
\draw[red,ultra thick] (0,0) rectangle (0.5,0.5);
\fill [draw=none, fill=white, fill opacity=0.3] (0,0.5) -- (A.north west) -- (A.north east) -- (A.south east) -- (0.5,0) -- (0.5,0.5) -- cycle;
\end{tikzpicture}
\end{frame}

\end{document}

Code:

Modified to generate the image above.

\documentclass[border=2pt]{standalone}

\usepackage{tikz}

\newcommand\tikzmark[1]{\tikz[remember picture,overlay] \node (#1) {};}
  
 \newcommand*{\Size}{2.5}%

\begin{document}
\begin{tikzpicture}
    \node[anchor=south west,inner sep=0] at (0,0) {\includegraphics[scale=0.1]{./images/EiffelWide.jpg}};
\end{tikzpicture}
%
\begin{tikzpicture}
    \node[anchor=south west,inner sep=0] (A) at (0,0) {\includegraphics[scale=0.1]{./images/EiffelWide.jpg}};
    
    \draw[red,ultra thick] (0.5\pgflinewidth,0.5\pgflinewidth) rectangle (\Size,\Size);
    
    \fill [draw=none, fill=white, fill opacity=0.4] 
        (\pgflinewidth,\Size) -- 
        (A.north west) -- (A.north east) -- (A.south east) -- 
        (\Size,\pgflinewidth) -- (\Size,\Size) -- cycle;
\end{tikzpicture}
\end{document}

Best Answer

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