Manga Converter — Matcha Reader Tools

📖 Manga Converter

Converts manga into the reader's panel format: detects panel rectangles, asks Gemini what text appears in each panel (plus an English translation), and packs everything into the binary format the device reads natively.

1. Choose your manga

Tap to choose a .cbz / .zip / .epub / .pdf — or select page images

Page order follows the same natural filename sort the device uses (cover and copyright pages pinned first). EPUBs use their spine order and native table of contents automatically; PDFs use document order (pages rasterized at 2× like the desktop tool).

2. Panel detection

AI panel detection — the same YOLO26 model as the desktop Python tool, running in your browser (~21 MB one-time download, then cached). Untick to use the white-gutter grid heuristic instead. 1-bit BMP (Floyd–Steinberg dithering) — write pages and panel crops as black-and-white dithered BMP instead of JPEG. The device paints these with a single fast refresh (no 4-level gray pass), so pages and panels turn noticeably quicker. Best for pure line art; screentone gradients become dither patterns. Pairs naturally with “Skip OCR”. Also export a portable EPUB — an extra .epub in the download for other e-readers/apps that don't have Matcha's panel navigation. Each page is followed by its panels as full-screen pages (wide panels rotated to show as large as possible), and the chapter list is kept as the EPUB table of contents. Panels are JPEG and pages keep their JPEG/PNG format — both standard EPUB image types, so the BMP option doesn't affect it. Adds memory and time for big volumes.

Target resolution

Downscales pages and panels to fit the chosen device screen (landscape images fit the rotated box), so the download is smaller and the device decodes far fewer pixels per page — no visible quality loss. Never upscales. Applies to every format (JPEG/PNG/BMP) and the EPUB. Leave on Original to keep full resolution.

3. Text recognition (Gemini)

Gemini API key — free at aistudio.google.com. Stored only in this browser; sent only to Google.

Skip OCR (panels only — no dictionary lookup or translations)

Advanced

Gemini model Panel crop margin (px) Only convert first N pages (for testing)

4. Book details (optional — auto-detected from EPUB/ComicInfo when present)

Title

Author

Chapters — one per line: page | title, 0-based final page number. Overrides the EPUB's own chapters.

OCR sends each panel image to the Gemini API and can take a while for a full volume — keep this tab open. The screen is kept awake during conversion. On the free API tier, rate limits may make long volumes slow; the converter retries automatically.

Install on the device

The download is a zip with one folder (named after the title). Put that folder anywhere on the SD card — /manga/YourTitle/ is a nice convention — either with a card reader or via the reader's Wi-Fi web file transfer. The device finds any folder containing panels.idx automatically, at any depth.