Layers are independent image layers in Photoshop/GIMP that enable nondestructive editing. They can be edited, moved, or hidden individually. Different layer types and blending modes allow flexible corrections, compositing, and effects without changing the original image. An important practice is duplicating and locking the background layer to protect the original.
Category: Photography – Advanced Topics > 11. Advanced Image Editing Article ID: 11.1 Created: May 2026
The essentials at a glance
- Layers are independent image layers stacked on top of one another—each can be edited separately without affecting the others
- The layer model is the foundation for nondestructive editing in Photoshop and GIMP
- Layers enable corrections, compositing, text, and effects that can be undone or changed at any time
Explanation
What is a layer?
A layer is like a transparent sheet placed over the image. Several layers stacked on top of one another combine to create the visible overall image. Each layer:
- Can be edited, moved, scaled, or deleted independently
- Can be transparent or partially transparent
- Has its own blending mode (how it is combined with the layers underneath)
- Can be shown or hidden
Analogy: Imagine a slide projector system in which several slides are projected on top of one another. Each slide is a layer—you can remove, replace, or move individual slides without touching the others.
Layer types in Photoshop
| Layer type | Description | Typical use |
|---|---|---|
| Pixel layer | Contains image data (pixels) | Image content, retouching |
| Adjustment layer | Corrections without changing pixels | Brightness, curves, color (→ Article 11.2) |
| Fill layer | Solid-color area or gradient | Backgrounds, color grading |
| Text layer | Editable text | Labels, graphics |
| Smart Object | Linked object that can be transformed losslessly | Applying filters nondestructively |
| Shape layer | Vector shapes | Graphics, frames, masks |
Layer modes (blending modes)
Each layer has a blending mode that determines how its pixels interact with those underneath:
| Mode | Effect | Typical use |
|---|---|---|
| Normal | Layer covers everything underneath | Default |
| Multiply | Darkens (like two slides stacked on top of one another) | Adding shadows, dodging |
| Screen | Lightens (the inverse of Multiply) | Adding highlights |
| Overlay | Increases contrast—lighter areas become lighter, darker areas darker | Dodge & Burn, increasing contrast |
| Soft Light | Softer version of Overlay | Subtle contrast enhancement |
| Luminosity | Only brightness is applied; color remains unchanged | Sharpening without color halos |
| Color | Only color is applied; brightness remains unchanged | Color grading |
Nondestructive editing with layers
The layer model enables nondestructive editing: The original image is never changed as long as you work on separate layers. All corrections can be undone or adjusted at any time.
Destructive (avoid):
- Painting, erasing, or making corrections directly on the background layer
- Applying filters directly to pixel layers without using a Smart Object
Nondestructive (recommended):
- Use adjustment layers for corrections (→ Article 11.2)
- Perform retouching on a new empty layer
- Apply filters as Smart Filters to Smart Objects
- Leave the original image untouched as a locked background layer
Layer order and transparency
Layers are rendered from top to bottom—the topmost layer is “in front.” Transparency (opacity 0–100%) determines how strongly a layer covers what is underneath.
Practical consequence: An adjustment layer at the very top of the stack affects all layers underneath. An adjustment layer between two image layers affects only the layers below it.
Practical tip
As a first habit when opening a new project: Immediately duplicate the background layer (Ctrl/Cmd + J) and lock the original background layer. Do all further work on the copy or on new layers. This way, the original is always preserved—even if everything else goes wrong. Sooner or later, this one habit saves every project.