Large images not centering

Question

I have this code:

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage[margin=2.5cm, showframe]{geometry}
\usepackage{pgfplots}
\usepackage{graphicx}
\usepackage[skip=0.33\baselineskip]{caption}
\captionsetup[figure]{
    font=bf,
    size=normalsize,
    justification=centerlast,
    }
\usepackage[labelformat=simple]{subcaption}
    \captionsetup[subfigure]{
    font=normal,
    size=normalsize,
    justification=centerlast,
    }
\renewcommand*{\thesubfigure}{Panel \thefigure\Alph{subfigure}:}

\newcommand{\plotheight}{0.425}
\newcommand{\plotwidth}{1.45}

\begin{document}
\begin{figure}[ht]
    \centering
    \begin{subfigure}{0.5\textwidth}
        \centering
        \includegraphics[width=\plotwidth\linewidth, height=\plotheight\textheight]{monkey.jpg}
        \caption{Monkey 1}
    \end{subfigure}\\
    \centering
    \begin{subfigure}{0.5\textwidth}
        \centering
        \includegraphics[width=\plotwidth\linewidth, height=\plotheight\textheight]{monkey.jpg}
        \caption{Monkey 2}
    \end{subfigure}
    \vspace{2ex}
\caption{Monkey Plot}
\parbox{\linewidth}{\small{This figure contains an image of the same monkey twice.}\vspace{2ex}}
\end{figure}
\end{document}

which produces this output:

When the width of the images are less than or equal to 1, both images are centred. However, when I insert a width value larger than 1, then the images are skewed to the right, as shown in the picture.

I do get a warning from LaTeX that the images are too wide. Although, the images seems to fit perfectly fine if centred.

Does anyone have an idea what the problem is?

Thanks in advance!

Edit: the real images I am using in my report are vector based, hence they will not be distorted. But thanks to those pointing that out.

Answer 1

Your MWE does the following:

• The subfigures are set to the fixed width of 0.5\textwidth.
• Inside the subfigures, the included images are set to \plotwidth\linewidth.

Inside the subfigures, \linewidth equals 0.5\textwidth. If you now set \plotwidth to a factor larger than one, the images will get a width that is larger than that of the subfigure. That's why you get the warning, and also centering doesn't work for overflowing stuff.

What you should do instead:

• Set the subfigures to a width \plotwidth\textwidth where for \plotwidth you can choose (and easily adjust) any number between 0 and 1.
• Inside the subfigures, set the width of the included images to the fixed \linewidth.

This way, you have the flexibility you wanted to have with your construction, but there will never be an overflow of the subfigure.

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage[margin=2.5cm, showframe]{geometry}
\usepackage{pgfplots}
\usepackage{graphicx}
\usepackage[skip=0.33\baselineskip]{caption}
\captionsetup[figure]{
    font=bf,
    size=normalsize,
    justification=centerlast,
    }
\usepackage[labelformat=simple]{subcaption}
    \captionsetup[subfigure]{
    font=normal,
    size=normalsize,
    justification=centerlast,
    }
\renewcommand*{\thesubfigure}{Panel \thefigure\Alph{subfigure}:}

\newcommand{\plotheight}{0.425}
\newcommand{\plotwidth}{0.7}

\begin{document}
\begin{figure}[ht]
    \centering
    \begin{subfigure}{\plotwidth\textwidth}
        \centering
        \includegraphics[width=\linewidth, height=\plotheight\textheight]{example-image-a}
        \caption{Monkey 1}
    \end{subfigure}\\
    \begin{subfigure}{\plotwidth\textwidth}
        \centering
        \includegraphics[width=\linewidth, height=\plotheight\textheight]{example-image-b}
        \caption{Monkey 2}
    \end{subfigure}
    \vspace{2ex}
\caption{Monkey Plot}
\end{figure}
\end{document}

Some more comments:

• You might want to change the use of \plotheight in a similar way, to have a consistent scheme for both dimensions.
• You might want to reconsider setting both width and height separately, or at least to add the keepaspectratio option.