[Tex/LaTex] How to achieve top-alignment of images in subfigure

Question

There are some threads about subfigures and alignment, but I could not find a solution for my problem. I want to have two figures side by side, both with their own capture (a and b) and below one capture for both. Using

\documentclass{article}
\usepackage{subcaption}
\usepackage{graphicx}

\begin{document}
\begin{figure}
    \centering
    \begin{subfigure}[b]{.49\textwidth}
        \centering
        \includegraphics[width=6cm]{example-image-a}
        \caption{Caption describing fig a}
        \label{fig:figure_a}
    \end{subfigure}\hfill%
    \begin{subfigure}[b]{.49\textwidth}
        \centering
        \includegraphics[width=7cm]{example-image-b}
        \caption{Caption describing fig b}
        \label{fig:figure_b}
    \end{subfigure}
    \caption{Caption for both images}
    \label{fig:Filter_L_LCL}
\end{figure}
\end{document}

gives me this:

and using my graphics I get this, so it is quite the similar situation:

Exactly what I want, expect the image alignment. I'd like to have them top-aligned and captions bottom-aligned (the image size must not be changed since image and document font size match). How can this be done? Any solution without manually shifting?

Answer 1

You can obtain it with the floatrow package:

\documentclass{article}
\usepackage{geometry}
\usepackage{subcaption}
\usepackage{graphicx, floatrow}

\begin{document}

\begin{figure}
\floatsetup{valign=t, heightadjust=all}
\ffigbox{%
\begin{subfloatrow}
\ffigbox{\includegraphics[width=6cm]{example-image-a}}{\caption{Caption describing fig a \label{fig:figure_a}}}
\ffigbox{\includegraphics[width=7cm]{example-image-b}}{\caption{Caption describing fig b} \label{fig:figure_b}}
    \end{subfloatrow}}
    {\caption{Caption for both images}
    \label{fig:Filter_L_LCL}}
\end{figure}

\end{document}