我怎样才能强制使子图对齐？

Question

我有 4 张图片，我希望它们都沿着垂直和水平边缘对齐。问题是右上图片上的标题占了 2 行，而左上图片上的标题只占 1 行，导致它们错位。它看起来像这样

我怎样才能强制它们对齐？我正在使用以下包和模板：

\documentclass[annual]{acmsiggraph}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}

\begin{document}

\begin{figure}[htbp]
    \centering
    \begin{subfigure}[b]{0.2\textwidth}
        \includegraphics[width=\textwidth]{images/donald}
        \caption{Original image.}
        \label{fig:pearl-original}
    \end{subfigure}
    ~ %add desired spacing between images, e. g. ~, \quad, \qquad, \hfill etc. 
      %(or a blank line to force the subfigure onto a new line)
    \begin{subfigure}[b]{0.2\textwidth}
        \includegraphics[width=\textwidth]{images/donald_gray}
        \caption{The image after blurring and extracting the luminance channel.}
        \label{fig:pearl-human}
    \end{subfigure}
    ~ %add desired spacing between images, e. g. ~, \quad, \qquad, \hfill etc. 
      %(or a blank line to force the subfigure onto a new line)
    \begin{subfigure}[b]{0.2\textwidth}
        \includegraphics[width=\textwidth]{images/donald_sobel_x.png}
        \caption{The image after applying a vertical sobel filter.}
        \label{fig:pearl-paint}
    \end{subfigure}
    ~ %add desired spacing between images, e. g. ~, \quad, \qquad, \hfill etc. 
      %(or a blank line to force the subfigure onto a new line)
    \begin{subfigure}[b]{0.2\textwidth}
        \includegraphics[width=\textwidth]{images/donald_sobel_y.png}
        \caption{The image after applying a horizonal sobel filter}
        \label{fig:pearl-paint}
    \end{subfigure}
\caption{Different stages of the image processing pipeline.}
\label{fig:pipeline}
\end{figure}

\end{document}

Answer 1

您可以使用\begin{subfigure}[t]{0.4\linewidth}，即 [t] 而不是 [b]。

我尝试使用以下包和模板：

\documentclass{article}
\usepackage{caption}
\usepackage{graphicx}
\usepackage{subcaption}
\captionsetup{compatibility=false}

\begin{document}


\begin{figure}[h!t!b]
    \centering
    \begin{subfigure}[t]{0.4\linewidth}     \includegraphics[width=\linewidth]{"image".png}
        \caption{image1}
    \end{subfigure}
    \begin{subfigure}[t]{0.4\linewidth}
    \includegraphics[width=\linewidth]{"image".png}
        \caption{image2 has a very long caption to be fit}
    \end{subfigure}\\
    \begin{subfigure}[t]{0.4\linewidth}
    \includegraphics[width=\linewidth]{"image".png}
        \caption{image3}
    \end{subfigure}
    \begin{subfigure}[t]{0.4\linewidth}
        \includegraphics[width=\linewidth]{"image".png}
        \caption{image4}
    \end{subfigure}

    \caption{Different Images}
    \label{Images}
\end{figure}


\end{document}  

Answer 2

如果图像高度相同且标题长度不同，则对齐图像顶部是合理的：

\documentclass{article}     % i haven't your document style,
                            % however a proposed solution work witha anyone
\usepackage[demo]{graphicx}
\usepackage{caption}
\usepackage{subcaption}

%-------------------------------------- only for show page layout
\usepackage{showframe}
\renewcommand\ShowFrameLinethickness{0.25pt}
\renewcommand*\ShowFrameColor{\color{red}}
%---------------------------------------------------------------%
\usepackage{lipsum} 

\begin{document}
    begin{figure}[htbp]
    \centering
       % images in the first row
       \begin{subfigure}[t]{0.2\linewidth}
        \includegraphics[width=\linewidth]{images/donald}
        \caption{Original image.}
        \label{fig:pearl-original}
    \end{subfigure}
    ~
    \begin{subfigure}[t]{0.2\linewidth}
        \includegraphics[width=\linewidth]{images/donald_gray}
        \caption{The image after blurring and extracting the luminance channel.}
        \label{fig:pearl-human}
    \end{subfigure}

    % images in the second row
    \begin{subfigure}[t]{0.2\linewidth}
        \includegraphics[width=\linewidth]{images/donald_sobel_x.png}
        \caption{The image after applying a vertical sobel filter.}
        \label{fig:pearl-paint}
    \end{subfigure}
    ~
    \begin{subfigure}[t]{0.2\linewidth}
        \includegraphics[width=\linewidth]{images/donald_sobel_y.png}
        \caption{The image after applying a horizonal sobel filter}
        \label{fig:pearl-paint}
    \end{subfigure}
\caption{Different stages of the image processing pipeline.}
\label{fig:pipeline}
    \end{figure}
\end{document}

（红线表示页面布局）

编辑：我不小心上传了两个不同的代码。另外，我错过了你喜欢将图像放在两行（这从你的代码中看不出来。现在已更正。

如果你的文档有两列，那么宽度为subfigures 的选择

\begin{subfigure}[t]{0.4\linewidth}

或者

\begin{subfigure}[t]{0.4\columnwidth}