I am going to write a beefed-up version of what the previous guys mentioned in summary form - this might help a little better to understand LWF.
1.) Go to File>Preferences>Display - go to the Color Management tab.
Here is where you set up Softimage to use a Color Profile (LWF- gamma adjusted) to aspects of Softimage. In the “Apply To” section, I check all of the boxes available to me. (There is a new one now for FXTree, so I haven’t looked into that yet). This will set up Softimage to work in LWF (Linear Work Flow). You will also now notice that your “color chips” you will see a “marquee” style hash line that goes around the boxes. That signifies that those colors are now setup for LWF as well, which is important.
2.) Go to File>Preferences>Rendering - go to the Images tab.
Color Profile - Linear (Default)
Here you will find a setting for Color Profile. This tells Softimage what color profile to use when accessing images during rendering. I believe the Default is set to Linear, which is what I use and I think works the best. Some people have this set to “Automatic,” but then you are leaving it to Softimage to decide on how to handle certain image files. By leaving this set to Linear, you are essentially telling Softimage to put all accessed image files into a Linear Color Profile. This is what you want to have happen, and work with, for pretty much any image that will not be used as a Diffuse image for your objects. Such as, Bumps, Displacements, Specs, HDRIs, etc, will want to keep them as Linear.
Now, when you have a texture that is going to be used as a Diffuse - I.E. the color map for an object, you want that to be in Color Profile - sRGB. How to change this, is when you are working with your Diffuse Texture, go into the Images PPG when you are in the Render Tree. Next, go to the “Adjust” tab for that texture. In that panel you will now see a section for Color Profile. This, as Default, will be matched to what you have this set to in the Preferences (Linear by Default). Now, go to the Dropdown and change it to sRGB. You have to do this for all of your Diffuse/color textures that you use, there is a way to do more of them at one time, if need be, but I don’t want to confuse anyone right now with extra information.
The above basically sets you up now to work in LWF. You can now add your exposure shader into the Pass Shaders and use the Preview button to see your setup and adjust accordingly.
Important: After you set everything up and you are happy with how it looks, and your next step is to render to final; if you want the gamma to be “baked” in, so it will basically look like what you have on the screen, make sure you check the “Apply Display Gamma Correction” box in the Output area of the Render Manager. (It usually sits in the middle panel near the bottom.) This will render your image as you see it on your screen. If you do not want the gamma “baked” in, then do not check that box. Leaving this unchecked is the preferred way to work in LWF. It will render out your image darker (basically stripping out the added gamma), then however you add that back in, in post.
For FXTree, or any post compositing software, do all of your color adjustments first, then at the very end of your tree is where you add your gamma adjustment node. You can use a Color Correct node or an HSVAdjust, or some others to do this in the FXTree. I find the HSVAdjust works easiest as they are all grouped nicely together in the “basics” area. Here is where you will set your final desired gamma settings (~2.2) for the R/G/B channels. Then send it out to process and you are all done.
I hope this better explains it for you. I wrote it out long also, so others can see as well in case someone else is having an issue with his.
Hope this helps.
Thank you for clearing that up for me. I guess this is the magic formula that I was looking for all this time. I just never knew what it was called. I always felt that there was something missing with the default renders generated by SI. However it all makes sense now