Highlight regions in an image with CLI
I have an image (a photo) and I want to highlight certain parts of this. I want to do this from the CLI.
I am planning to store the pixel coordinates of polygon vertices in a file, and when I run a script, a new image should be applied with the polygons highlighted. I am going to be making a lot of tweaks to the file, which is why I want the coordinates of highlighted areas in a text file.
How can I accomplish this? I am comfortable programming if that is the easiest option.
2 answers
You are accessing this answer with a direct link, so it's being shown above all other answers regardless of its score. You can return to the normal view.
The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| matthewsnyder |
Thread: Works for me Exactly what I was hoping for! Magic, indeed. |
Aug 21, 2023 at 22:15 |
This is an ideal case for ImageMagick.
Given input.png:
Running this command:
convert input.png -draw 'fill yellow fill-opacity 0.5 polygon 50,50 100,30 150,50 100,150' output.png
Produces output.png:
For far more information, see the documentation.
Another possibility is to use LaTeX. There are several ways in which you could use it to add a polygon on top of an image, one way is TikZ:
% !TeX program = txs:///arara
% arara: pdflatex: {synctex: on, interaction: nonstopmode, shell: yes}
\documentclass[tikz,convert]{standalone}
\begin{document}
\begin{tikzpicture}[inner sep=0pt]
\node {\includegraphics{example-image-duck}};
\draw[red] (0.5,0.75) -- (0.75,0.5) -- (0.5,0.1) -- (0.25,0.5) -- cycle;
\end{tikzpicture}
\end{document}
If compiled with shell-escape enabled, this will automatically convert the resulting vector image back into a pixel graphic.
If you don't want to create a separate file with the LaTeX code, you can directly use it from the CLI via
pdflatex --shell-escape "\documentclass[tikz,convert]{standalone}\begin{document}\begin{tikzpicture}[inner sep=0pt]\node {\includegraphics{example-image-duck}};\draw[red] (0.5,0.75) -- (0.75,0.5) -- (0.5,0.1) -- (0.25,0.5) -- cycle;\end{tikzpicture}\end{document}"
See https://topanswers.xyz/tex?q=4461 for a review of tools to convert the resulting vector image back into a pixel graphic
0 comment threads
0 comment threads