This video I'm going to show you a few techniques to combine selections and save them into like a reusable format so that you can create a mask that you can reuse over and over again in your in your workflow on a particular image.
Video: Creating and Saving Selections in Photoshop!
Load the image in Photoshop.
Make the selection around the tree trunk.
Press Hold or Alt on the keyboard to make a more accurate selection.
With the Selection made and to prevent yourself from recreating the same steps click on the the Channel Tab.
After you saved it you will see an Alpha 1 Channel if you click it you will see how the channel looks like.
Remove the unnecessary lines by using the brush tool, set the opacity level to 100%.
Press the Ctrl or Command D on your keyboard to deselect and remove the lines.
Proceed with the next trees with the sames steps from Step 2-Step 10.
Combine the three channel into 1 by pressing the Ctrl or Command and click on Channel Tree1.
By pressing Command and Shift (Mac) or Ctrl+Shift (Windows) click on Tree 2 and Tree 3.
Click on the icon at the bottom that says “Save Selection as Channel” to save all 3 trees as one channel.
Select the individual channels and remove it by dragging it down to the bin.
Press Command or Ctrl on your keyboard to now load this all trees channel as a selection.
Go back to the layers tab.
This will automatically add the selection to the curves adjustment layer.
Make the necessary changes on the curves layer and it will only affect the trees.
Add another curves adjustment layer.
Invert the layer mask by pressing Command or Ctrl+I.
Whatever changes you make on this layer will affect the image except the trees.
I liked the video on creating and saving selection in Photoshop, and would like to know something about luminosity masking.