Buffer Visualization Modes Are Inaccurate

In 4.18, Buffer Visualization Modes appear very similar to their representation in Buffer Overview. In 4.19 and Main (CL 4008322) the results are very blown out. Similar issue reported in UE-29947.

Per Licensee:

I believe that there may have been gamma issues with various Buffer Visualizations going back to at least Jan 8th 2015. However with the 4.19 release we are now seeing inaccuracy in the Base Color and World Space Normals buffer visualizations caused by the specular channel affecting the visualization. In some scenes this results in the visualization being so blown out that it becomes useless.

1. Open any level in 4.19 (I used RealisticRendering example project from launcher)
2. Change view mode to Buffer Visualization > Overview, note the appearance of the different views
3. Now change Buffer Visualization Mode to BaseColor, WorldNormal, Roughness, or any of the other options to compare to their appearance in step 2.

Result: Buffer Visualization results are inconsistent with Overview mode. Results tend to look very blown out.