Highlights
A useful PDF app for students and researchers
Free (IAPs) From Jonas Ribe, highlightsapp.net Needs macOS 10.15 or later
Highlights is a PDF reader designed specifically for students and researchers — developer Jonas Ribe created it to help with his own PhD research — and anybody else who needs to read, annotate and crib from PDF documents. In addition to familiar annotation tools it contains a number of useful features for getting information out of PDFs in usable formats.
The core Highlights app is free, but the most useful features require you to buy a Pro subscription — currently $2.99 a month with the obligatory free trial. The Pro subscription unlocks text and table recognition, exporting in formats other than PDF, support for math formulas, and custom accent colors. It applies not just to the Mac app but to the iPhone and iPad versions too.
Highlights initially feels like any other PDF reader, but there’s an extra panel that you can bring up on the right–hand side of the screen to which you can extract data in the appropriate format for reuse. For example, if you highlight a table in the PDF you can use the context–aware Smart Copy tool to copy the table data as CSV data; if you do the same with an image, you can copy the image, and for citations the format is BibTeX. We tried very hard to confuse Smart Copy but it coped admirably even with dense multi– page tables of data, albeit after a bit of a wait. Text is copied without formatting such as bullets and list numbering, which can result in hefty blocks of unformatted text.
Highlights can also translate images via machine learning. If the PDF makes use of images containing text or tabular data, Highlights can recognize and copy it.
In addition to copying data, you can supplement it with your own annotations and with Digital Object Identifier (DOI) links for citations. DOI links are unique identifiers for digital documents, and if the citation you’re using has a related DOI then Highlights will download the appropriate metadata. The app enables you to set default colors for different kinds of annotations so that you don’t have to change the settings with each new PDF. Once you’ve assembled all your data, Highlights can then export it in the appropriate format for reuse in Markdown, PDF, HTML or TextBundle, or send it to your preferred writing app.
THE BOTTOM LINE. Highlights does a good job of extracting and exporting data, images and text from PDFs.