To stop the images from fading quickly you need to keep talking if you can avoid it don't label what you see like house, ask yourelf what is it made of, what colour is it, how big is it, where is it, when have you seen something similar, how does it feel? Is there any sounds you can hear, does it give you an underlying sense of emotion (that's a difficult one so don't get hung up on it).Some time the image turns black before you have fully described it then call on what you remember of it. It will usually bring back that image.
If you feel you're forcing it start your image stream with a remembered dream, if the dream was vivid great start with that, even if it was only a part of a dream. As for the feeling that the subconscious is providing nothing... when does the subconscious ever really make itself felt? When you image stream it is a consious act and the conscious mind has always been the one that appears to make the decision what comes next but really... where did the idea come from?
Keep going with it, it takes a few days to get over the talking out loud self consciousness.
Alex
