I'm hoping someone can explain this to me...
Why do some of the MAT pose files for V4 and M4 use light blue for the diffuse color for the skin textures?
Actually, I think all of the texture packs I've bought for them are like that, but I don't have many. For all I know they're all like that.
It looks like hell - I just don't see any reason for it, since it multiplies that blue color over the texture color and in white lighting causes the skin to look greenish on a typical Caucasian texture.
Who decided that was a good idea?
You'd think they could at least give you some MAT poses without the blue, because it's a major nuisance to have to go and change all the skin diffuse colors to white after loading a MAT pose.

So aside from that, is there a way in Poser to make MAT poses that do nothing but change the diffuse color of a surface to a selected color, while leaving all other textures and shaders intact?

Just so I don't look totally dumb about it, I imagine there's a good reason for it - or at least a reason that makes sense for Poser use, but I'm not seeing it.

I'm guessing there's some supposed "realism" aspect to the idea, but at the same time, if they're shooting for realism, I'd have to question the reasoning behind setting the diffuse value to 1 - Meaning if they're using that light blue in some attempt to make the skin look more real, then I would think they would also set the diffuse value lower while they're at it, since skin doesn't have 100% diffuse in reality - more like 70% or so.

There is method to the DV=1 madness as well. It all has to do with NOT having gamma correction or SSS, so having to do some fakery to perform something that looks more like variations in redness in the skin and also something that does gamma compensation. Most forms of compensation involve adding more light, or reflecting more light. Most forms of skin SSS fakery involve removing some red as a basis (thus a light blue tint), then selectively adding it back in a non-uniform way.

I actually was the person who first posted the blue-red technique, although I later abandoned it for a number of reasons. It can produce a very good look, but only in a very limited range of lighting, and never works when real gamma correction is used. Face_off picked it up and used it in V3 shaders he made for Daz. He used it because it was a fake-sss technique that worked without scripting when moving lights.

Poser Pro did not exist then.

I later developed better ones, but the Daz copycats (vendors who copied the Daz V3 and V4 shader) never picked up on the newer techniques, or they found them too complicated. (The newer techniques require a lot more nodes)

You're right in thinking they were done as an attempt at realism.  You're also right in thinking they are lousy.  

BagginsBill's VSS takes care of the problems.  IIRC he posted an explanation for the weird looking setup on these textures, too.

As for changing only the diffuse, I believe ShaderSpider can do that (I don't have it so I can't say for sure.  Failing that, maybe a Python script could do it.

Aha!  Crossposted with BB himself. 

Okay thanks for the replies, guys.

Bagginsbill, I get what you're saying. Now I see why.
I'm using Pro 2010, and with the GC, yeah, it just doesn't work.

Sam Therapy, thanks for the suggestions. I don't know how to script, but I'll look into that shader spider thingie. Might be useful for other things anyway.

Edit-
Well it looks like Shader Spider only works with Poser 7, according to the DAZ page, but I appreciate the suggestion anyway.

You may find a script you can adapt to work the way you want.  I haven't tried it myself but I know of several scripts which work on only one part of a material.  Try requesting in the Python forum. 

Quote - I later developed better ones, but the Daz copycats (vendors who copied the Daz V3 and V4 shader) never picked up on the newer techniques, or they found them too complicated. (The newer techniques require a lot more nodes)

Haven't they ever heard of cut and paste?

Or VSS?

it's because they are descended from Smurfs

There were a few scripts to change only the diffuse color , and at least one was for only materials with skin in the name.   Try freestuff or the python forum. I dont have a copy of one I did.