Quote - When a JPEG is saved on a monitor that has a gamma of 2.2, the JPEG algorithm encodes the file with the appropriate gamma correction by raising the image's brightness to the power of 1/2.2 (most Windows monitors).  On a MacIntosh, however, the file will be encoded with a gamma of ~1/1.8.

A JPEG saved on a MacIntosh looks darker on Windows because it is decoded with a gamma of 2.2 instead of 1.8.  The inverse is true when a JPEG saved on Windows is dipslayed on a MacIntosh.  The image will end up looking brighter than it should.

If we do not know exactly where a JPEG comes from, we can only guess that the gamma value applied to the image must have been 2.2.  It could have been anywhere between 1.8 and 2.3.

In such cases we need to experiment with different gamma values.  Am I somewhat correct?  Please do not hesitate to correct me if I'm wrong.

not hesitating to correct you ;D.

Wikipedia

Quote - Many JPEG files embed an ICC color profile (color space). Commonly used color profiles include sRGB and Adobe RGB. Because these color spaces use a non-linear transformation, the dynamic range of an 8-bit JPEG file is about 11 stops. However, many applications are not able to deal with JPEG color profiles and simply ignore them.

afaik, Poser does not support reading color profiles.  that's not what makes you need to linearize your texture.  if the images are  created by a digital camera or scanner, those devices use sRGB space.  if you paint a texture, you see it through an sRGB device, so in that sense, the monitor will affect your image.  but not in the sense you seem to mean. 

it will just mean that when  you choose a color that looks right to you, it looks right to you on your monitor.  you could create linear versions of your images without Poser  (though i don't know how one would do it mathematically in Photoshop, and i'd hate doing it by eyeballing it myself).  conversely, if you use the right color space within Photoshop, you could probably set it up so that you create linear works that look like they're sRGB when you're editing them in Photoshop.  you could also work in other color spaces, like CMYK or Pantone colors.  it makes no difference to the JPEG itself. 

the issue is more that if it looks right on your screen, the renderer can't work with it.

in my experience, the difference between Mac and PC was easier to handle in post than the difference between GC equations and sRGB equations.  or actually, pretty much ignore and just use the same principles of making images that work in general on the web.  just like the sRGB printers and other digital devices do, in my expeience it's best to work to the specification.  at least for the raw render.