Lightroom masks - order and nature of operation

[gkroeger]

I haven't been able to find authoritative documentation from Adobe on how overlapping masks are handled in Lightroom. So question one is whether order of masks matters.

For example, if one mask raises saturation 10 units, and the overlapping mask lowers saturation by 5 units, does Lightroom first raise and then lower the saturation, or does it compute the net change for the overlapped area and just raise saturation by 5 units. As a parametric editor, the latter would be ideal, but I suspect the former may be how masks are actually implemented.

If masks are processed as separate operations, then order matters whereas if Lightroom computes the net change, then order is unimportant. This matters more for some operations than others. For example, raising sharpening and then lowering it in two steps is much different than just sharpening by the difference in the two masks.

If, in fact, each mask is applied separately, then I would assume that the order the masks appear in the masking panel is the order of operation, but is it top to bottom or bottom to top?

Thanks for any insights or experience you can provide.

Glenn

[nemophoto]

I have not found that it really processes in a particular order. For example, I have a client who insists on shooting in NC and SC during the winter months. I usually need to "create" foliage in the background on trees as well as green up bushes. (It's generally easier when I have them out of focus.) I'll usually do two overlapping masks of different colors of green and opacity to give the look and feel I want. I have had no issues. I'll also have a skin softening preset I created that I will use on models to even the skin tones. Sometime this may lighten a tad too much, so I'll over lay a brush to burn in.

Specifically, for your saturation question, it's all mathematical for LR. It will average to two to get to the point you have selected.