Not everyone has the supercomputer they dream of using for their renders; I am one of the crowd that has to cut RAM corners wherever I can just to get a scene to render. I have one dear friend whose computer cannot even handle rendering shadows at the same time as the rest of her scene, and gods help her if she should want ray-tracing! This is frustrating, and if you have an old machine limping along and whining any time you try to render an image you learn that the fewer images you load into Poser the better it runs.
Here is one of the little tricks I use to save RAM--instead of making a bump map for a texture, I just use the original texture.
I am using Michael 4 as an example. Here he is without any bump maps or special shaders, just plain (hi-res) texture map plugged into the main diffuse channel.
Smoooth. But with that scruff he'd much rather be craggy, so I'm going to throw some bumps on the poor man.
Open up your material room and select the material zone to be bumpified. Then go to the Bump channel and right click to open a new node, and navigate to math_functions, as below:
Set your bump value to whatever you like--.0005 is a little high for my taste but it will show the results more dramatically for tutorial purposes, so that is where I've set mine. On your Math node, select Subtract from the drop-down menu and give value_2 a value of 1.00. Then drag a connection from your texture node to value_2:
Note the dark areas now turned bright--these will be where your bump map is raised. Obviously this will work better with some maps than others. You'll just have to eyeball it and make sure you are not causing warts or blisters (unless you want those). But there it is, and the result below:
Voilà! Now you have a bump map of the same resolution as your master texture without adding the few megabytes of RAM that a real bump map would take up. Enjoy!
"Do you think, when further developed, this can replace bump map creation in general?"
No, it only works because the colour variations produce low grade greyscale noise in more or less the right places, but in general the colour variations don't correspond to what would be right for a bump map.
What bagginsbill says about displacement maps in this post
applies equally to bump maps.
There used to be a lot of old stuff which used a greyscale version of the texture in much the same way as this trick.
It was still being done when A3 came out. The Engineer Boots in the A3 Leather Set use a negative greyscale, and it looks as though you could just use a wholly procedural shader. That's a May '05 product, and the ReadMe says P4 or Pro Pack.
DAZ, ps_ac1181b, a nice enough set. The jacket is quite useful.
A well-presented and useful little tutorial, well done.
You might mention that the Bump value is in whatever Display Units are selected in Preferences. Your 0.0005 might be in Poser Native Units (if that's what you use), producing a maximum bump of around one-twentieth of an inch. Someone using the default Feet, or the more commonly-used Inches, would see hardly anything at all with that value.