Let assume you have some image files in local file system, by using below code you can able to copy image to Clipboard.
var currIamge = 'test.jpg' // mention your image path and name
var imageFile = Titanium.Filesystem.getFile(currIamge);
var imageBlob = imageFile.toBlob(); // convert image file into blob using toBlob() method
PS : Tested with iPhone and it works fine