[Tex/LaTex] Enlarge font size eps figure

Question

I have two eps figures and I'd like to enlarge the font size of labels Dimension 1 and Dimension 2 (Figure1) and Dimension 1, Dimension 2 and Frequency(Figure 2) in the two figures. This lables should have same size.

Figure 1

Figure 2

\begin{figure}[H]        
        \centering
        \subfloat[Polygonal scatterplot]{\includegraphics[scale = 0.62]{scatter_price.eps}\label{fig:scatter_price}}
        %\hspace*{-2em}    
        \subfloat[Histogram]{\includegraphics[scale = 0.4, trim = 1cm 2cm 1cm 1cm, clip]{hist_price.eps}\label{fig:hist_longair}}
    \caption{Histogram and symbolic scatterplot of response variable} 
\label{descriptive1}
\end{figure}

Answer 1

Just the idea:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usepackage{float}
\usepackage{subfig}

\begin{document}

\begin{figure}[H]      
        \centering
        \subfloat[Polygonal scatterplot]{\begin{tikzpicture}
        \node at (0,0) {\includegraphics[scale = 0.62]{fig1.png}}; % ADDING OUR PICTURE HERE 
        \fill[color=white] (-3.3,-1.5)--(-2.95,-1.5)--(-2.95,1.5)--(-3.3,1.5)--cycle; %HIDING OLD LABEL HERE WITH A RECTANGLE FILLED WHITE
        \node[rotate=90] at (-3.1,0) {\normalsize Dimension 2}; % ADDING NEW LABEL HERE WITH OUR CHOICE OF FONTSIZE (rotate starts from "3 o clock" and goes counterclockwise) 
        \end{tikzpicture}\label{fig:scatter_price}}
        %\hspace*{-2em}    
        \subfloat[Histogram]{\begin{tikzpicture}
        \node at (0,0) {\includegraphics[scale = 0.4, trim = 1cm 2cm 1cm 1cm, clip]{fig2.png}};
        \end{tikzpicture}\label{fig:hist_longair}}
    \caption{Histogram and symbolic scatterplot of response variable} 
\label{descriptive1}
\end{figure}

\end{document}

Result:

As you see the result is already different from yours because of the different format of the files (mine are png copied of your post)

Suggestion: try with red color in the rectangle until "deleting old label" to see it better.