How to Mark Up Paper Revisions with LaTeX? #

Below are three steps to highlight changes made in a paper revision with LaTeX. After these three steps, you will have a marked-up PDF that looks like this.

Step 1. Generate a submission snapshot #

We first take a snapshot of the last version of the LaTeX project before the paper's original submission. If you use Git to version control your project, it is easy to checkout the exact version used for the original submission.

Use latexpand to flatten the LaTeX structure. It combines all LaTeX files into one file.

# After submission, before revision
latexpand --empty-comments f01-main.tex > submission.tex

If you are updating any figure, give it a new name (e.g., figures/{figure-name}-old.pdf) and update its reference in submission.tex. We need to have both the old figure and new figure to show the differences in Step 3.

Step 2. Generate a revision snapshot #

Once you have made all the revisions, you can take a snapshot of the latest version similar to Step 1.

# After revision
latexpand --empty-comments f01-main.tex > revision.tex

Step 3. Highlight the changes #

We use latexdiff to highlight the changes made during the revision.

Copy your submission.tex and all old figures (e.g., figures/{figure-name}-old.pdf) to your current project directory.
Create three configuration files for latexdiff.

You can copy my configuration into three files diff-preamble.tex, diff-config.cfg, and diff-safecomp.cfg. You can learn more about the configurations on latexidff's documentation.

File 1: diff-preamble.tex

This file defines how to style the additions and deletions.

% [diff-preamble.tex]

\RequirePackage[normalem]{ulem}
\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
\providecommand{\DIFadd}[1]{{\protect\color{BLUE}#1}}
\providecommand{\DIFdel}[1]{{\protect\color{RED}\sout{#1}}}
\providecommand{\DIFaddbegin}{}
\providecommand{\DIFaddend}{}
\providecommand{\DIFdelbegin}{}
\providecommand{\DIFdelend}{}
\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
\providecommand{\DIFdelFL}[1]{\DIFdel{#1}}
% I don't like the default undercurl for added text, so I commented it out below
% \providecommand{\DIFdelFL}[1]{}
\providecommand{\DIFaddbeginFL}{}
\providecommand{\DIFaddendFL}{}
\providecommand{\DIFdelbeginFL}{}
\providecommand{\DIFdelendFL}{}

File 2: diff-config.cfg

This file tells latexdiff to show the deleted image in the original scale.

SCALEDELGRAPHICS=1

File 3: diff-safecomp.cfg

This file tells latexdiff what are the "safe commands" that it can check textual differences. If you define any macros that wrap some text, you can put it in the list below. For example, myquote is a macro of \newcommand*\myquote[1]{``\textit{#1}''}.

myquote
multirow

Generate diff.tex using latexdiff.

latexdiff submission.tex revision.tex > diff.tex --graphics-markup=2 -p diff-preamble.tex --append-safecmd=diff-safecmd.cfg --config=diff-config.cfg

Generate diff.pdf from diff.tex.

pdflatex diff
bibtex diff
pdflatex diff
pdflatex diff

🎉 Open diff.pdf, you should see all revision changes to text and figures being highlighted.

[Recommended] Finally, to speed up the generation process, you can combine all commands into a bash script and run it instead: zsh diff-generate.sh.

# [diff-generate.sh]

latexpand --empty-comments f01-main.tex > revision.tex

latexdiff submission.tex revision.tex > diff.tex --graphics-markup=2 -p diff-preamble.tex --append-safecmd=diff-safecmd.cfg --config=diff-config.cfg

pdflatex diff
bibtex diff
pdflatex diff
pdflatex diff

Bonus #

I also like to use \usepackage{todonotes} to highlight specific reviewer comments next to my changes. To do that, you only need to add \todo{} in your new LaTeX files.

For example, below is an example of the marked-up revision for our CHI'23 paper GAM Coach using latexdiff and todonotes.

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