I have tried various image formats in the _canonical_uri field (png, jpg and bmp) but none are recognised. Do I need to convert my image to another format? As there size requirements. I assume the image can be added to the wiki in the normal way.
…which then renders as the favicon correctly. (noting that the type field of $:/favicon.ico needs to match for the image to render when that tid is viewed within TW, but will work as a favicon to the browser even if the type is wrong (I just noticed mine had type to text/vnd.tiddlywiki. The favicon worked, but setting it to image.png meant it also worked within TW