How to log scaling applied by \includegraphics?

Question

I'm currently working on a large-ish document that contains a lot of screenshots. These range from relatively small dialog boxes or details of the screen to some very large overview pictures. I currently use the option width=\textwidth for the larger screenshots to scale them down to fit the page (somewhat). I also need to apply some scaling to the other screenshots - some larger images need to be scaled down, some details need to be scaled up.

Now I would like to use a small set of scaling factors throughout the document. The screenshots are all taken from a single application, and I'd rather not have the font size and UI details change size from image to image. To achieve that, my current plan is to use only two or three fixed scaling factors throughout the document. I can apply these manually in the source code, but I need to determine the actual values first. For that, I was thinking about setting every image to width=\textwidth, recording the actual scaling applied and then classifying and adjusting the scaling factors.

As far as I can see, the original size and the requested size of each image file is contained in the log file, but on separate lines and in a syntax that is not very parser-friendly. Is there a better way to log the actual scaling factor that is applied to the image?

Answer 1

You could try this:

\documentclass{article}
\usepackage{graphicx}
\usepackage{etoolbox}
\makeatletter
\appto\GPT@setup@scale{\wlog{x-scale: \Gin@scalex, y-scale: \Gin@scaley}}
\begin{document}
\includegraphics[width=\textwidth]{example-image-duck}

\includegraphics[width=\textwidth]{example-image-a}

\end{document}

It will log

File: example-image-duck.pdf Graphic file (type pdf)
x-scale: 1.8696, y-scale: 1.8696

and

File: example-image-a.pdf Graphic file (type pdf)
x-scale: 1.07413, y-scale: 1.07413