Dark mode PDFs in Zotero, and what it still will not do
Zotero handles dark reading better than it used to. What it still does not do is change the file, so the paper is bright again the moment it leaves Zotero.
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Zotero 8 fixed the worst of it, and deserves credit for that
Until early 2026, Zotero inverted images along with everything else, and researchers rightly complained that micrographs became negatives and plots stopped matching their legends. Zotero 8 replaced that with reader themes that darken images slightly instead of inverting them. If you are on a current version and using the default Dark theme, your figures are no longer being destroyed. That was the right fix and it is worth saying so plainly.
Two places inversion still happens
The Black theme, added in 8.0.1 to reproduce the old Zotero 7 look, has Invert Images switched on by default — so the theme most likely to be chosen by someone who liked the previous appearance is also the one that still turns figures into negatives. The same option is available, and on, for custom dark themes. Zotero's mobile apps have also historically lagged behind the desktop reader here, so check what yours is doing before assuming parity.
The part no reader theme can fix
A theme changes what Zotero draws on your screen. It does not change the PDF. Send the paper to a co-author, open it on an iPad, drop it into a shared folder, or print it, and it is white again — because nothing about the document itself was ever altered. This is not a shortcoming of Zotero specifically; it is true of every reader that offers a dark theme.
Converting the file instead
This rewrites the colours inside the PDF, once. Photographs and micrographs keep their own colours and are only dimmed. Charts keep the data colours their legend refers to, which matters when a caption says "blue line". Backgrounds and body text move onto a dark ramp. The result is an ordinary PDF that is dark in Zotero, dark on your tablet, and dark for whoever you send it to.
Your library still works normally
Attach the converted file to the Zotero item, or replace the existing attachment. Because the conversion edits colour instructions rather than flattening pages into images, the text layer survives — so Zotero indexes it for full-text search exactly as before, and highlights and annotations behave normally.
Questions
Does Zotero still invert figures in dark mode?
Not by default on current desktop versions. Zotero 8 changed the reader themes to darken images rather than invert them. The Black theme, which reproduces the older look, does still invert images by default, and mobile apps have historically lagged behind the desktop reader.
Why is my paper white again on my iPad?
Because a reader theme changes what Zotero draws on screen, not the file. The PDF still contains its original colours, so any other app opens it bright. Converting the file is what makes the change travel with it.
Will charts keep the colours their legend refers to?
Yes. Charts and diagrams keep their data colours while their white background goes dark, so a caption that says "blue line" still points at a blue line.
Does Zotero still search the text of a converted paper?
Yes. The conversion rewrites colour instructions rather than turning pages into images, so the text layer is intact and full-text search and indexing work normally.
What about a scanned paper with no text layer?
It converts and reads well, with scanner speckle cleaned up first. A scan that never contained selectable text will not gain one — that would need OCR, which is a separate thing.