In the absence of specific alterations to their default formatting code, WordPress-based websites use the canvas element to detect whether the browser can correctly render emoji. Because Tor Browser does not currently discriminate between this legitimate use of the Canvas API and an effort to perform canvas fingerprinting, it warns that the website is attempting to 'extract HTML5 canvas image data. Ongoing efforts seek workarounds to reassure privacy advocates while retaining the ability to check for proper emoji rendering capability.
