Difference between revisions of "Layers"

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(Layer structure)
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===Layer and spacial structure===
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There is, believe it or not, a correlation between the structure of a layer stack and volumetric picture space. Things that are further down in the stack should be further back in space. This make the file easier to organise (e.g. reduce contrast into the depth) and to read.
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There is also clear linkage between a layer to which a bunch of other layers are stacked and an object. This 'master clip' layer tends to be an object (figure, house etc). These objects are usually grouped and can be moved around as objects within the scene complete with all their stacked adjustments.
  
 
==What can go wrong?==
 
==What can go wrong?==

Revision as of 09:41, 21 January 2012

This is the heart of Photoshop. The Photoshop file format has a layered structure. Simply put: each document is composed of many image layers on top of each other. This enables each part of the final ‘composite’ image to be changed independently of the others. The composite image in the document window is a flattened view of all of these separate layers.

Interface 11.png

Bottom of palette

The bottom of the Layers Pallet contain a set of icons that are used for creating items within the layer stack.

Interface 12.png

Linking

Two layers linked will move unison. Useful for web design, interface design etc. To a digital painter this is not really useful.

Layer effects

Activates layer effects from a menu. These are pre-made effects such as: drop shadow, inner glow, emboss etc. These are useful for web design, interface design etc. In this course this is not only not important but actively discouraged. Layer effects are inflexible and not suited to picture construction.

Mask

Creates a mask. A mask is a non-destructive way or erasing the contents of a layer. This is vital to digital painters and compositors. A mask is often twinned with a selection in the following manner: after a selection is made the mask button is pressed, the subsequent mask being derived from the selection. More in the [[Selection to Mask

Adjustment layers

Creates an adjustment layer. Adjustment layers are non-destructive versions of the Adjustments that can be found in the Image / Adjust menu. These are very useful, however the only useful ones are Curves and Hue Saturation.

Group

Create a group. A group is a collection of layers which can then be switched off and on separately to the rest of the layer stack. In a complex file you are probably going to need to color these through the contextual menu near the Layer Visibility icon. A Layer Group can also be masked. This enable 'double masking' which is very useful for moving masked objects behind other object that lie on their background layer.

I find the easiest way to create these is to make a selection of layers and then select New Group from Layers from the #Menu.

Layer

Create a layer (or Option Shift N).

Delete

Deletes selected layers.

Top of palette

Interface 14.png

At the top of the Layers Pallet there are some controls that govern the properties of selected layers.

Lock

For locking various aspects of the layers. We often need to lock the transparency of a layer when we are painting on it.

Blend Mode

Sets the blend mode of the layer. Vital. Some Blend Modes are very, very, very, very useful.

Opacity

This set the transparency value of the layer. Surprisingly, we hardly every need to change this value. If you need to make something lighter then use Curves, if you need to make it transparent then add a grey to a mask.

Fill

We never, ever need to change this value. What is the difference between this and Opacity? Google it.

Menu

A few (but not many) interesting commands, e.g. select a bunch of layers and the New Group from Layers.

Layer syntax

Photoshop layering has a syntax: a vocabulary to the way that the layers are arranged. This might be different according to your needs. It is ok if a painting file consists of no more than a little layered compositing (maybe just a few Blend Modes layers clipped to a painted layer), but a compositing file is likely to be more complex. Either way, I wish you to observe the convention that follows. This convention, as well as being a naming agrement, is also a guide to how the compositing structure is organized.

Layer structure conventions

All layers should have valid names. 'untitled layer 2' is not a valid name. Layer naming as below:

Naming convention.png

A - Content layers
Always descriptive and start with capitals.
B - Adjustment layers
Left to default naming unless otherwise needed.
C - Blend mode layers

Always simple initials in lower case. Follow this convention:

Blend mode
Naming Convention
Multiply m
Screen s
Overlay o
Color Burn cb
Color Dodge cd
Color c
Saturation s
Hue h
D - A simple cloned or painted addition
Mark as 'Add'.

Grouping

If your Photoshop file has more than one group of layers (a group being defined as an image layer with multiple adjustment and blend mode layer above it) then the group must be separated by Layer Groups (menu: Layer / New / Group from Layers). Color those groups (right click on group and select color).

By the way… do not clip to layers that are completely opaque. Clipping only works if the layer is at least partly transparent.

Naming convention 02.png

Layer and spacial structure

There is, believe it or not, a correlation between the structure of a layer stack and volumetric picture space. Things that are further down in the stack should be further back in space. This make the file easier to organise (e.g. reduce contrast into the depth) and to read.

There is also clear linkage between a layer to which a bunch of other layers are stacked and an object. This 'master clip' layer tends to be an object (figure, house etc). These objects are usually grouped and can be moved around as objects within the scene complete with all their stacked adjustments.

What can go wrong?

The following is based on the kind of things I see in poorly managed student files (and in my own).

  • It is possible to name a layer m indicating that its blend mode has been set to Multiply, yet forget to actually set the layer blend.
  • One major trouble that people are always having is not knowing where they are in the Layer Pallet. They might be busy painting away on one layer, really thinking that they are in another layer or be painting in the Layer Mask by accident. Do not be fooled by what you see in the Document window. Always be aware of where you are in the Layer Pallet.
  • A clipped layer is only necessary if the bottom layer contains some transparency values. If it is completely opaque then dont clip.
  • Deciding what is ok to destructively edit and what is ok to non-destructively edit can be a difficult job. Non-destructive editing can very addictive, but it is only necessary if it is necessary (got it?). Tip: layers set to layer blends almost always contain semi-junk information can be be easily replaced. These is no need to non-destructively edit them. Also, it is perfectly ok to merge many painted addition or clone layers.

Layer Palette keystrokes

These are the most important Layer Pallet keystrokes to know:

Action
Keystroke
New layer (with dialogue) Command Shift N
New layer (without dialogue) Command Shift Option N
Duplicate layer Command J
Duplicate layer into another document Right Click then Duplicate Layer from contextual menu then select destination.
Merge layers Select layers then Command E
Make new layer from merged layer stack Copy all into clipboard: Command A then Command Shift C, then paste: Command V