After last update picker doesn't work at look. It sees page in different zoom or something like that, because real pixel color mismatch with scanned by addon one.
Hello, please try the latest version v3.3. It should fix the issues you were experiencing.
If it fixes things, we would appreciate if you could consider amending your review.
In case of any issue please feel free to contact us at http://colorzilla.com/contact/. We are committed to quickly fix all issues and provide you with the most sophisticated color tool on the market - for free!
