Hi,
Paul, thanks for the link, that technique is great!
Rory, In my experience the issues with the masks with complex structures such as foliage are due to CA and Purple fringing, which makes the edges fuzzy, creating a problem for the mask.
Here is the technique that I use:
I will mask the sky in the following picture:
To create the mask, I will perform some edits that will be reversed at the end, so it is good to take note of white balance and contrast
Step 1: Increase contrast to 100%
Step 2: Change to Black and White
Here a 100% crop of the upper right part after those steps
Play with the B/W controls until you get the accentuated borders. In this specific case I reduced the Blue control to -67 obtaining the following image:
Now change the White Balance until you get sharp edges (it works as if it was eliminating the CA). In this case I had to increase the Color temperature up to 11560, obtaining the following result
Now go back to colour and apply the technique described in Wayne's video, and you start getting the mask as shown in the next image
However, if we apply an extreme edit, we can see that there are like "dust specs" around the image as shown here:
Well, just click a few more times in areas similar to original and the mask keeps getting better
Now you can continue building the mask. In complex images may be necessary to repeat the steps of going back to B/W and adjust the color temperature.
When the mask is ready, reverse the original image white balance and contrast and apply the desired adjustments to the brushed area. In this case I desaturated and lightened the sky
Here a 100% crop with the adjusted sky
And here a 100% crop of the original image in the same area (brush off)