[Added after the original post. Eric Chan has informed me that there are two image-processing pipelines in Lightroom: output-referred, and scene-referred. Raw files get the scene-referred pipeline. Integer TIFFs get the output-referred pipeline. Therefore, the TIFF test images are getting a different set of processing than LR applies to raw files.]
Now for a three-dimensional look at the results from the previous post. First, the Lightroom images. The a* axis is on the right, and the b* on the left.
The baseline exposure:
Basically, there’s just a little bit of noise. All the values are between L* = 48.85 and a hair over 48.95.
One stop underexposed:
Two stops underexposed:
Three stops underexposed:
Four stops underexposed:
Pretty much the same story in all of the underexposures; the blue/cyans and magentas are darker than they should be.
I’ll spare you looking at all the Photoshop images. Here’s the worst, the four-stop-under one:
Just noise on the L* axis, and not much of that. A really fine performance.