There is nothing simpler than creating a mask, even a channel mask.
- Use the mask icon from the panel pallete (whole layer)
- create selection, click on mask icon (selection become hidden)
That's it. No fuss no difficulty, yet.
To create a channel mask you have two ways:
- Click on channel tab, Ctrl-Click on any of the icon. This will create
- A mid to high luminosity Selection range (all colors)
- A Red, Green or Blue color luminosity selection*
- Click on mask icon, done
- Use Ctrl-Alt-(2, 3, 5, or 5)
- Ctrl-Alt-2 creates a mid to high luminosity Selection range (all colors)
- Ctrl-3, 4 or 5 creates a mid to high luminosity Selection range (R, G or B)*
A channel mask is complex and uses shades of grey vs the simple B&W you have seen before.
* Note that the color selection do not use the same range than the full luminosity selection. This is due to the RGB+L channels that compose the full image.