Dark Slide Ink-Saver Inverter
Print dark lecture slides without draining ink cartridges: backgrounds flip to white, photos stay true — all in your browser.
- What you type or open in this tool stays in this browser tab and is never uploaded.
- No account, no sign-up
- Inputs stay in this tab
Slides PDF
Preview
How it decides what to flip
Each page is rendered to a canvas and measured: if less than half the pixels are dark, the slide is already ink-friendly and is left alone. Dark pages get their grayscale inverted — white text on black becomes black text on white — while 32×32 px blocks whose channel spread exceeds the saturation threshold (photos, diagrams, colored charts) keep their original colors, so X-rays and figures don't turn into negatives.
Everything runs locally with pdf.js; your course material never leaves the browser. The toner-savings number compares dark-pixel coverage before and after the flip — a rough planning figure, not a lab measurement.
Free, and honestly labelled ads
Free no signup, no card
- Unlimited use
- Works offline after load
- No account required
Why there is no paywall deliberate
This tool never touches a server, so it costs almost nothing to run. Ads are labelled, never interstitial, and never placed between you and a result.
Pricing benchmarked against what the incumbents charge. See the full monetization map →
This file is processed in your browser and is never uploaded — this page carries no ad slot. See all 27 tools · Privacy · How these are paid for