Send a blob with ajax, don't work in my case

Question

So, i have an image on my page with this for src attribut :

src="blob:47d2cdd6-0ff0-401f-a195-a671d0db9b05" 

I need to send this blob to php with ajax, for save this blob (a gif in my case) on my server.

This is my ajax :

var data = new FormData();
data.append('file', $('myImage').attr('src'));

    $.ajax({
        type:"POST",
        url: "/webcam/",
        data: data,
        contentType: false,
        processData: false,
        success: function () {
            parent.$.fancybox.close();
        },
        error: function() {
      alert("not so boa!");
    }
    });

But, when i am on my php script, i don't know how to use this blob... When i try readimageblob() from imagick for example, i have an error.

Am i in the good way ?