Bilibili Manga Watermark Remover: The Complete Guide to Traceless, Lossless Removal
Bilibili Manga Watermark Remover: The Complete Guide to Traceless, Lossless Removal
That corner logo every manga reader knows
Nobody notices the watermark while reading manga inside the Bilibili Comics (B漫) app — until you want to save a page. Wallpaper, video editing assets, reading lists, fan translations: the moment you hit "save", that semi-transparent "bilibili 漫画" text in the corner tags along. Screenshots carry it. Online watermark removers mangle it — manga pages aren't photos, they're lines, halftone dots, and flat color, and any AI-based "regeneration" blurs the crisp linework into mush.
The twist is that Bilibili Comics watermarks aren't random: they're a fixed template composited onto the page. That means there's a cleaner path than guessing — mathematical recovery.
An open-source project on GitHub, bilibili-manga-watermark-remover (261 stars), walks exactly that path: traceless, lossless, with a GUI and pre-packaged Windows exe. This article covers how it works, how to use it, and the pitfalls.
1. Why Bilibili Manga watermarks can be removed "losslessly"
First, understand how the watermark is applied. It's not an opaque logo stamped on the image — it's a watermark image with an alpha channel composited over the original:
out = in × alpha + watermark × (1 - alpha)
alpha is the watermark's transparency channel; every pixel of the watermark is semi-transparent. The key insight: if you know alpha, you can reverse the formula and recover the original pixels exactly.
One catch: images downloaded from the web don't carry an alpha channel. You get the already-blended result; the alpha lives only on the server.
How do you recover alpha? The project's trick: prepare a pair of watermark images — one on a black background, one on a white background — for each image size:
- On the black-background version: watermark pixels = watermark × (1 - alpha)
- On the white-background version: watermark pixels = 255 × alpha + watermark × (1 - alpha)
Subtract the two and alpha pops out. That's why the tool needs one black/white watermark pair per image size — Bilibili Comics serves pages at different resolutions, and the watermark template scales with each.
The algorithm originates from the yuchenxi2000/bilibili-watermark project; this repo turns it into a ready-to-run desktop app.
Why other approaches fail:
| Approach | Result | Problem |
|---|---|---|
| Screenshot cropping | No watermark | Loses part of the frame |
| Online AI removal | Looks clean | Linework and halftones get redrawn, quality loss |
| Blur / mosaic | Covered | Visible patch |
| Mathematical recovery (this tool) | Traceless & lossless | Needs black/white template pairs |
2. What the tool does
bilibili-manga-watermark-remover is maintained by indie developer lanyeeee — 229 commits, MIT license, released up to v0.10.0:
- GUI: built on Tauri v2 (Vue + UnoCSS frontend) — no command line required
- Zero-config launch: Windows users grab the exe from the Releases page and double-click
- Automatic template generation: point it at a manga folder and it auto-generates black/white watermark images for every image size found; if auto-generation fails, you can manually crop a watermark sample
- Batch processing: an entire folder of manga pages in one pass
- Traceless & lossless: output is pixel-identical to the original — mathematical recovery, not AI redraw
- Multi-platform: Windows exe, plus an AUR package (
bilibili-manga-watermark-remover) for Arch Linux
A companion project, bilibili-manga-downloader by the same author, downloads the pages; the two tools chain together: download, then batch-clean.
3. How to use it
Three steps:
- Select the manga folder containing the images
- Generate background watermarks: the tool scans all image sizes in the folder and auto-generates black/white watermark images for each. If a size fails, crop a watermark sample manually
- Run removal: click start, wait, check the output directory
The README includes a full demo video plus before/after comparisons from two real manga — Girls' Last Tour and Fire Punch — showing watermark regions cleaned up with zero smudging on the linework.
4. Why one template pair per size
This is the most common pitfall. People assume one set of watermark templates covers everything. It doesn't:
- Watermarks scale with image dimensions — a 1080p page and a 4K page use different template sizes
- Alpha must align pixel-for-pixel with the actual watermark; mismatched sizes produce garbage recovery
- So the tool scans the folder for every distinct image size and generates an independent black/white pair for each
Auto-generation works by locating the watermark at its fixed position (Bilibili Comics places it at the bottom or a corner), cropping that region, and compositing it onto black and white backgrounds. Manual cropping works too — the more precise the sample, the cleaner the recovery.
5. Known issue: antivirus false positives
The classic indie-developer headache: Windows Defender and other AVs flag unsigned exes as malware. The author says it plainly in the README — the proper fix (a code-signing certificate, which reportedly involves dealing with antivirus vendors) is effectively out of reach for individual developers.
What to do if you hit it:
- Confirm the download came from the official GitHub Releases page
- Verify the SHA checksum against the repo
- Add an exclusion in your AV
Or skip the exe entirely and build from source (next section) — the build is fully transparent.
6. Building from source (optional)
Three commands — you need Rust, Node, and pnpm:
git clone https://github.com/lanyeeee/bilibili-manga-watermark-remover.git
cd bilibili-manga-watermark-remover
pnpm install
pnpm tauri build
Stack: Rust (Tauri backend) + TypeScript/Vue frontend + UnoCSS + Vite. PRs must target the develop branch.
7. When to use this tool — and when not to
Use it when:
- You read Bilibili Comics and want clean saved pages
- Quality matters — AI redraw smudging is unacceptable
- You're archiving manga in bulk
- You want everything local, with zero uploads
Don't use it when:
- You're dealing with screenshots, photos, or video watermarks — use a general AI watermark remover instead (this blog has plenty of reviews)
- You need other manga platforms (Tencent Comics, Kuaikan, etc.) — their watermark mechanics differ, templates don't transfer, though the idea does
8. The takeaway
The lesson worth keeping from Bilibili Manga watermark removal isn't the tool itself — it's that fixed-template watermarks can be recovered mathematically. Alpha blending is reversible: get the template, recover the original, no AI needed. The same idea powers the reverse-alpha recovery of Gemini image watermarks and the NotebookLM watermark-cleaning ecosystem across GitHub.
Bookmark this project. Next time you need a clean manga page, you won't be stuck sighing at a watermarked screenshot.