Lighting an Exterior Daylight Scene - Photographic Rendering with V-Ray for SketchUp - page 132

This checkbox was originally added to V-Ray as a quick-fix option for a "double
gamma" or texture-brightening problem that many artists were running into whenever
they used images or bitmaps as the diffuse component in a material.
Essentially, images that come from applications such as Photoshop, or even directly
from a digital camera, already have a brightening curve or gamma correction applied
to them. This is done to make the images created in a software application or taken
by a digital camera (both of which are in linear color space by default), more closely
match the way that our eyes and brains interpret illumination levels and color values
in real life.
The Linear Workflow switch does this by reversing the gamma correction (often
referred to as de-gamma or linearizing) already applied to the image. In V-Ray
however, this de-gamma process doesn't just get applied to images used as the dif-
fuse component of a material but also to any colors set by means of its diffuse color
swatch.
This, in many ways, is what SketchUp users are used to seeing in their viewport.
There (whenever a surface is viewed directly or head on), the bitmap or color seen
in the viewport pretty much exactly matches what is being seen in the SketchUp ma-
terials editor.