Add color to an equation over an image using overpic

Question

I'd like to add a couple of equations over a picture. I'm using the overpic package as explained in overpic_link. However, I'm trying to get the equation in color as shown in color_link

\documentclass{article}
\usepackage[percent]{overpic}
\usepackage{xcolor}

\begin{document}
\begin{overpic}[width=0.5\textwidth,grid,tics=10]{pictures/baum}
 \put (20,85) \textcolor{blue}{\huge$\displaystyle\gamma$}
\end{overpic}
\end{document}

but I'm getting the error below: ! Package xcolor Error: Undefined color `\hss '. could anyone please provide a feedback on why the error, I'm just starting using Latex, thanks.

Answer 1

The correct syntax is

\put(<x>,<y>){<material>}

and you're missing the braces around the material you want to \put.

Spaces around the coordinates are ignored.

\documentclass{article}
\usepackage[percent]{overpic}
\usepackage{xcolor}

\begin{document}

\begin{overpic}[width=0.5\textwidth,grid,tics=10]{example-image-9x16}
 \put (20,85) {\textcolor{blue}{\huge$\gamma$}}
\end{overpic}

\end{document}

I removed \displaystyle that does nothing here, but it could make a difference with more complicated formulas.