See your design as colour-blind readers see it
About 1 in 12 men cannot tell your red series from your green one. Drop the chart and find out whether the message survives.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
Loading the tool…
How it works
- Drop an image, screenshot or PDF.
- Pick the deficiency — deuteranopia is the most common.
- Compare, and export the view or a 4-up comparison sheet.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
How accurate is the simulation?
It uses the Machado (2009) physiologically-based matrices applied in linear light — the model behind most accessibility tooling. It represents typical perception for each deficiency; individuals vary.
What should I look for?
Anything that was only distinguishable by colour: chart series, form errors marked in red, status dots. If two things merge in the deuteranopia view, add a second channel — labels, shapes or patterns.
Why does it accept PDFs?
Because reports and slides are where colour-coding does the most damage. Pages are rasterised for the simulation, one page at a time.