Pixel layers are what you will use to edit an image w/o destroying it, as illustrated by the third layer I had you create, if you follow my very basic tutorials in order.
In some cases you need to create an adjustment layer using a pixel layer. My choice of words is confusing here, I am aware of that. As an example, to reduce color noise in an image you will use a dominant pixel layer that has been blurred tehn select a blend mode that makes sense for your image. Add a controling mask to your effect and you reduce color noise effectively without reducing you initial image sharpness. This is why I call some pixel layers 'adjustement'.
You can also control the white balance of an image using a pixel layer, there are numerous youtube videos that show you how. I modified what is shown in the videos and obtain better results, this will part of pointed tutorial, same as color noise removal.
Pixels layers are created by:
- Duplicating another pixel layer like the background (Ctrl-J)
- Creating a new pixel layer (Shift-Ctrl-N)
- Inserting an object using a selection cut and paste (Ctrl-X Ctrl-V) or copy (Ctrl-C Ctrl-V)
- Inserting a new image from an external source
What you must remember, and this important, whenever you use a pixel layer it is applied before a mask takes effect.