You can quite easily, you develop the film but don't fix it and bleach the silver away before re-exposing it to light and developing it again and then fixing it, giving a positive image.
Unfortunately using that method you are limited to film speeds of 200 or below as otherwise the contrast of the final positive image will be extremely low because obviously your reversing the rules of film, now the slower the speed of the film, the higher the contrast rather than the higher the speed.
The DR5 Chrome process that I mentioned above is different in that its a chemical reversal process rather than an optical one so the same rules apply and you can reverse most films, even Tmax 3200 or Delta 3200 but unfortunately most don't quite meet their box speed so your limited to ISO 1000 with both of those. A lot of popular ones such as FP4+ and Tmax 100 and 400 can be shot at practically box speed with perhaps the loss of 1/3rd of a stop.
However you can shoot above or below the recommendation with push and pull processing because they act like slides now with the more limited exposure latitude so up to a point you have a lot of control because you have to inform them of the ISO you shot it at.
Its just a shame that the only lab that does it is in Colorado and its a secret how its done as its a great service but then it is a unique process and requires a unique processor as well. It would be nice if they would license it to somewhere in the UK though.
