How to send canvas to server?

Question

PHP

There is nothing tricky about sending the form to the server with Ajax.
There is nothing tricky about drawing an image in an HTML5 Canvas.
But I'm trying to send a picture from Canvas and I'm in a stupor :)
On the canvas side, everything is OK, the picture is ready, stuffed into data:image/png;base64,....... and transmitted by Ajax to the server in $_POST[' picture'].
The server, on the other hand, expects a picture in $_FILES - and in general this is good, you cannot refuse this useful mechanism.
But $_FILES is empty... Ajax knows nothing about it, and it won't work with the form: it's not the file uploaded by the user that is sent to the server, but the result from the Canvas. And here is the ambush.
All I found about this is one and a half articles for 200 * year and error 404 everywhere ...
What to do, comrade?

Answer 1

stackoverflow.com/questions/13198131/how-to-save-a...
And for some reason I found it. Strange, right?
There is also a link in the answer:
stackoverflow.com/questions/1532993/i-have-a-base6...