A KOReader plugin for peeking at maps, family trees and other reference images from anywhere in a book, without losing your place.
No more bookmark → contents → find the map → navigate back. Open Glimpse, swipe through the book's reference images, zoom, and close. You're still exactly where you were.
- Finds the images worth seeing. Maps, family trees, diagrams and illustrations surface automatically; covers, logos, ornaments and dividers are filtered out. Illustrated non-fiction keeps its smaller figures too.
- Browse them all. A Gallery lays every image out as a grid, and a tap jumps straight to any one.
- Reopens where you left off. Comes back to the last image you viewed, at the same zoom and pan. Handy when you keep returning to one corner of one map.
- Spoiler-safe by default. Shows only images up to where you're reading; switch to the whole book whenever you want.
- Readable at night. Line-art illustrations stay visible in night mode instead of vanishing into the dark page.
- Customizable. Choose where the drawer sits (a side panel, or a top or bottom band in portrait), arrange the viewer's ⋯ menu, add nav arrows, a zoom pill or a mini-map for panning while zoomed, and tune the zoom limit.
 A diagram open in the viewer. |
 The same diagram in night mode. |
 The Gallery shows every image at once. |
 Choosing where the drawer opens. |
 A bookmarked page with the mini-map. |
The easiest way is Storefront, a plugin browser for KOReader that installs and updates Glimpse for you.
To install manually:
- Download the latest
glimpse-vX.Y.Z.koplugin.zipfrom the releases page. - Unzip and copy the
glimpse.koplugin/folder into KOReader'splugins/. - Restart KOReader.
After that, update from inside KOReader: Tools → Glimpse → Updates → Check for updates.
Open it. With a book open: Tools → Glimpse → Open Glimpse. Better, bind a gesture under Settings → Taps and gestures → Gesture manager → pick a gesture → Reader → Open Glimpse. One-touch access is the whole point.
In the viewer:
- Swipe left/right to move between images.
- Tap a dot to jump straight to an image.
- Double-tap to zoom in, again to zoom back; drag to pan.
- Prefer buttons? Add a zoom pill (+ / fit / −) or ‹ › nav arrows from Quick Actions.
Switch modes from the viewer's ⋯ menu: flip between Spoiler-free and All images without leaving your place.
Make the ⋯ menu yours under Tools → Glimpse → Quick Actions: hide rows you don't use, add nav buttons or captions. Gallery stays pinned at the bottom.
| Setting | What it does |
|---|---|
| Enable Glimpse | Master switch. Off silences Glimpse without unbinding its gesture. |
| Mode | Whether images past where you're reading stay hidden. Default hides them. |
| Include Bookmarks in Gallery | Also show your bookmarked pages in the Gallery, in reading order. |
| Quick Actions | Choose which actions appear in the viewer's ⋯ menu. |
| Layout | Where the drawer opens: a side panel (left/right), or a top or bottom band in portrait. |
| Show Nav Buttons | ‹ › arrows in the viewer for switching images. |
| Navigation Loops Around | ‹ › and swipes wrap past the ends; Gallery pages too. |
| Show Zoom Controls | A + / fit / − pill in the viewer for zooming. |
| Show Mini Map | While zoomed, a small overview marks the visible area; tap to jump. |
| Invert Images in Night Mode | Show images inverted (light on dark) in night mode. |
| Show image captions | Show the book's caption for an image, in the corner. |
| Show bookmark label in corner | On a bookmarked page, show its page number and chapter in the corner. |
| Maximum zoom | How far double-tap and pinch can zoom in (150–400%, default 200%). |
| Enable top menu tap zone | A tap along the top edge opens KOReader's top menu over the viewer. |
| Gestures | Toggle double-tap zoom, swipe-to-navigate, and pinch zoom. |
| Disable irrelevant image filtering | Show every image in the book, including covers and ornaments. |
| Suppress "format not supported" notice | Silence the message when Glimpse opens on a non-EPUB file. |
| Disable shadows | Remove the drawer's shadow if it leaves e-ink ghosting. |
| Fast image switching | Flashless refresh between images; turn off if images ghost through. |
| Rescan this book | Drop the cached scan if the file changed or images look stale. |
| Check for updates | Fetch and install the latest release, with a restart. |
| Include pre-release versions | Also offer test builds. |
⋯ → Gallery lays out every image as a masonry grid, numbered in reading order. Tap a thumbnail to jump to it; page through with the arrows.
With Include Bookmarks in Gallery on, your bookmarked pages appear in the grid too, in reading order. Tap one to view it full-size; Show in Book jumps there. To drop a bookmark, use Remove bookmark (long-press in the Gallery, or the ⋯ menu). It deletes the bookmark in the book itself, not just its Glimpse cell.
Ignored images. When the filter sets an image aside (or you ignore one), a Gallery | Ignored switcher on the bottom bar shows both piles with their counts. Long-press a thumbnail to Ignore it or Add back to Gallery. That recovers a map the filter hid but you actually wanted, without switching to All images. Your choices persist per book.
./release.sh 0.2.0 --notes "what changed" # builds + publishes a PRE-release
./release.sh 1.0.0 --final # a real release, visible to updaters
DRYRUN=1 ./release.sh # build the zip onlyPre-releases are invisible to the normal update check (releases/latest skips them), so they form the opt-in test channel behind "Include pre-release versions".
Glimpse is translated on Crowdin, and help is welcome. No programming is needed: pick your language, fix the AI-drafted lines that sound wrong, and your work ships with the next version. See CONTRIBUTING.md.
- EPUB, FB2 and MOBI (and other HTML-based formats crengine renders) are supported. PDF, DjVu, comics and manga get a polite "not supported" message.
- Spoiler scope tracks the chapter you're currently in, not the furthest you've ever read. A MOBI holds the whole book as one HTML document, so Glimpse cannot place an image in a chapter. On a MOBI the mode is locked to "All images" and the switcher is greyed out. Your setting is kept for EPUB and FB2 books.
plugin/ the plugin (copy/stage as glimpse.koplugin/)
main.lua KOReader wiring: menu, gesture action, scan cache,
viewer subclass (dots, captions, hide, swipe-nav)
glimpse_scanner.lua pure Lua, no KOReader deps: EPUB container/OPF/HTML
parsing, FB2 (base64 <binary>) and MOBI (crengine
mobi_image_N) scanners, image-header dimension
sniffing (PNG, JPEG, GIF, WebP, BMP, SVG), filter
heuristics
builder/
check.sh syntax gate + fixture regen + unit tests; run it
before calling any change done
make_fixture_epub.py deterministic fixture EPUB (stdlib only) with
trap cases (ornaments, dividers, commented-out
markup, URL-encoded paths, SVG)
scanner_tests.lua headless tests against the extracted fixture
smoke_userpatch.lua userpatch that exercises the live plugin inside a
running KOReader (see file header)
stage.sh checks + builds dist/glimpse.koplugin + zip
The scanner takes an injected read_file(archive_path) function; inside KOReader that is crengine's getDocumentFileContent (with a libarchive fallback), in tests it reads the extracted fixture. Image dimensions are sniffed from file headers; no image decoding happens during a scan, and a full decode only happens for the image currently on screen.
Glimpse is free software under the GNU Affero General Public License v3.0 or later (AGPL-3.0-or-later); full text in LICENSE. Use it, fork it, modify it freely; if you distribute a modified version, ship its source under the same terms. Community translations via Crowdin are under the same licence.
Copyright (C) 2026 Erik Fanki