How can I get the center of a scaled image wherever I want it---(x,y)---in the document?

Question

According to some coordinate system, whatever that may be, how can I position a scaled image where I want it in the document using the center of the image as the point of reference? For example, something like this:

\being{whatever}(4cm,6cm)
     \includegraphics[scale=0.5]{img.jpg}
\end{whatever}

---

Here is my minimal working whatever:

\documentclass{article}
\usepackage{something}
\title{Cartesian closed categories and the price of eggs}
\author{Jane Doe}
\date{September 1994}
\begin{document}
   \maketitle
   Hello world!
\end{document}

Answer 1

Simply replace the text that was being placed with the appropriate \includegraphics:

Below is an adaption of What are the ways to position things absolutely on the page to use \includegraphics[<<options>>]{<<file>>} instead of given text.

Code:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
%% ------ https://tex.stackexchange.com/a/169836/4301
%% Following obtained from \layout. May need adjustment based on class and
%% page settings.  Alternatively, can set these to 0pt and then position will
%% be relative to bottom left of page.
\newcommand{\BottomLeftX}{1.0in+\hoffset+\oddsidemargin}%
\newcommand{\BottomLeftY}{\paperheight-1.0in-\voffset-\topmargin-\headheight-\headsep-\textheight}%
\newcommand*{\AbsolutePosition}[4][]{%
    % #1 = tikz options
    % #2 = x (from south west corner of page
    % #3 = y
    % #4 = text
    \begin{tikzpicture}[remember picture,overlay, ultra thick]
        %\draw [shift={(#2,#3)},#1]  (current page.south west) circle (2pt) 
        \draw [#1]  ($(current page.south west) + (\BottomLeftX,\BottomLeftY) + (#2,#3)$) 
            %circle (2pt) %  adding [opacity=0.2] to the node below will let you see this reference point
                node[] {#4};
    \end{tikzpicture}%
}
\title{Cartesian closed categories and the price of eggs}
\author{Jane Doe}
\date{September 1994}
\begin{document}
   \maketitle
   Hello world!
\AbsolutePosition[fill=red,draw=red]{7.0cm}{12.0cm}{\includegraphics[scale=0.1]{../images/EiffelWide}}
\end{document}