For instance I'd like to desaturate the Image_Map, in this screenshot; in order to then plug that into the Bump channel, of the PoserSurface.  My first instinct is to open Photoshop, desaturate, and create another map; but this takes time, and especially...RAM?

Likewise I am interested in knowing how to increase the amount of Saturation in an image.

I'm also wondering how to brighten/darken an image?  I understand how to increase/decrease the Difuse Color and/or Value of a material; but could this happen before the Poser Surface?

And now that I'm thinking of it, it would be nice to have a simple place to referance any/all Poser functions, that would save me time and RAM from Photoshop?  Like take Contrast, for example; is it possible to raise/lower an Image_Map's contrast, within Poser? 

I know some Photoshop functions would be very tuff, like Levels; and others would be a little obscure, like many Brush strokes.  But I'd still like a firm grip on when to think of opening Photoshop, and when to just add a node. 

So, if anyone has any questions and would like to ask here; or if you may just have a tip to add, please do so?  Any replies will be greatly appreciated!

Plug a Math->hsv node into the image_map node. You can then set the saturation to 0 to greyscale the image map for your bump channel. I do that quite a lot.

I think all the value inputs (with numbers) desaturate, only the color inputs pass the color data, so just plug the image into the bump input and adjust the value. If you want a negative image use a math or colormath node, set to subract your image from one or white.
The gain function is the easiest way to adjust the contrast. .5 is no change, zero results in .5 gray, 1 is on or off if the input is greater, or less than .5 (on or off instead of white and black because the colormath node handles red, green and blue independantly).
You can adjust an exploding displacement map with a subtract node.
Be sure to open the previews the results can be easily viewed.

Raven - Thank you very much, that was just the answer I was looking for!

"I think all the value inputs (with numbers) desaturate, only the color inputs pass the color data, so just plug the image into the bump input and adjust the value."

I see Poser renders differently; when a Desaturated texture map is plugged into the Bump, VS. when the same image is used with Saturation.

" The gain function is the easiest way to adjust the contrast."

*Thank you very much!  I looked for a Gain node, but did'nt see how to create one?

Attached Link: http://castleposer.co.uk/articles/maths_gain.html

Gain is one of the Math node options.

Gain is a math function.