Adjustbox do not scale up smaller image does not work

Question

I am trying to set the max width of an image by using the adjustbox package. What I want is that an image only scales DOWN to \linewidth if needed. But if it smaller than \linewidth then it should NOT be scaled at all. However when using the following code, the image gets still scaled to \linewidth

\documentclass[a4paper]{scrreprt}


\usepackage[pdftex]{graphicx}


\usepackage[export]{adjustbox} 


\begin{document}
xxxxx
\begin{figure}[H]
    \centering
    \adjincludegraphics[max width=\linewidth]{images/dialog.png}
    \caption[asdf]{asdf}
    \label{fig:dialog}
\end{figure}
yyyyyyyyyy
\end{document}

What did I miss?

Answer 1

Some information is missing from your question. Since, I do not have that specific image to test with, I must raise a few queries.

1. Did you crop out the required dialogue box from your screenshot and then used the cropped image in LaTeX?
2. If so, post-cropping did you resize the image? If not, as @LaRiFaRi mentions, what is its original resolution? For example, width=221 pixels at 96 dpi & height=334 pixels at 96 dpi

This way, looking at the original resolution of just the required part within your screenshot (e.g. the dialogue box) should give you an idea.

3. Also, do you intend to use \linewidth or \textwidth? Both are quite different! In your current situation, the difference may not matter. However, from the conventional point of view:

A \linewidth is defined as -- The width of a line in the local environment.
A \textwidth is defined as -- The width of the text on the page. (fixed design-oriented length) ; for reference, see: LaTeX default lengths

Also see this scintillating discussion on Difference between \textwidth, \linewidth and \hsize, which includes a nicely illustrated example that shows the difference between these lengths in different situations.

4. To print the exact size of either of these lengths, use the following after \begin{document} :

   textwidth = \the\textwidth ; linewidth = \the\linewidth ; hsize = \the\hsize

   In onecolumn mode, all three lengths should be equal.

5. Now, you can compare your original image resolution and the size of your selected width parameter to determine if the image is smaller or larger than the width. For unit conversions, see: Units used in LaTeX

That should provide you with enough tools to troubleshoot your own problem! Happy hunting!!