Now that the Map Rectifier has the Mapnik OpenStreetmap layer, its possible to register, rectify and warp an uploaded image using the OSM data and then, using the WMS plugin to see the resulting image in JOSM.
I took a photocopy of a 1933 Ordnance Survey map of the Headingley area (you can just about see the cricket ground bottom left), and then, not having access to a scanner, took a mobile phone photo of that photocopy, and uploaded it to Map Rectifier.
Using the OSM layer, I was able to rectify the image, and experimented with a number of different warping options (think I settled on Quadratic Fit).
Since there is a WMS link to the warped image, I was able to alter the Landsat plugin in JOSM to make it show the rectified image.
This could allow you to digitize ways, label streets, fill in areas (like that cricket ground!)
The plugin is based on the Landsat plugin (with menus from osmarender plugin), with tweaks to get the URLs that are generated from the Rectifier working too. It should also work with any WMS too, and it defaults to Landsat. In theory it would be possible to see the Mapnik/Osmarender WMS in JOSM using this plugin too… might be useful?
The Plugin installs a “WMS” menu, with four items: 1) to set a fully formed WMS url, 2) to use a Map Rectifier URL, and 3) to default back to using Landsat. There’s also an option to get some information and help (4). You can also change the WMS url using the advanced preferences wmsplugin.url.
Of course, make sure that licence, terms of any WMS and the copyright of the rectified image covers use for OpenStreetMap.
Full WMS example:
Metacarta Map Rectifier WMS URL input format example: