Creating layers

Like selections and masks, before we can start working with layers, we need to define what they are and how they can be created. It is helpful to think of layers as a form of mask as well, in that is shows, hides or protect the layer below it.

WHAT ARE LAYERS?

LAYERS are similar to acetate sheet (clear plastic film) stacked on top of one another so that:

• The underlying pixel of each non-overlapping pixels show though
• The underlying pixel are blended together using a blend mode.
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Except for a regular layer or adjustment layer, many layers are created AUTOMATICALLY:

Some layers are created AUTOMATICALLY when the following items are used:

1. Type Tool
2. Shape Tool
3. When an Adjustment Layer is created
4. When Copy and Edit > Paste Special > Paste Into menu is used.
5. When a existing layer is duplicated (e.g., CTRL + J)
6. When and Filter Mask is created using a Smart Object
7. When and image is Inserted

You will learn how some layers are AUTOMATICALLY created when the following techniques or tools are used:

1. Text tool is used.
2. Shape tool is used.
3. Layer is duplicated (e.g., CTRL + J) will copy the whole layer if there is no selection to another layer or will copy just the selection to another layer.
4. Image is inserted will automatically create a mask.
5. Image is pasted into a selection (e.g., Copy and Edit > Paste Special > Paste Into) will create a new layer and a layer mask.
6. An Adjustment Layer is created (e.g., black and white, hue saturation). All the layers below it will be "adjusted" based on the adjustment type, unless there is a selection. In which case, only the selected area will be adjusted. The exceptions to the Adustment Layers are the first three options (Solid Color, Gradient, and Pattern) which create a mask on the ACTIVE layer.
7. A Filter Mask is created. When a layer is converted to a Smart Object (e.g., Filter > Convert For Smart Filter) and then a filter is added to that layer, it will automatically create a Filter Mask layer. Unlike both the Layer and Vector Mask which the mask is to the the right of the image and unlike the clipping mask in which the mask is above the layer, a filter mask is on a layer BELOW the image.

HOW DO YOU CREATE THESE LAYERS?

1. ADJUSTMENT LAYERS

ADJUSTMENT LAYERS can be compared to a camera's len filter or sunglasses where the image is always the same but is changed because of the "lens" that it is viewed through.  Hence, you can change the appearance of an image (hue,brightness, etc.) without permanent  affecting the image.

TIP: It is best to use an adjustment layer rather than a regular layer because an adjustment layer is non-destructive whereas a regular layer is permanent.  Hence, you can make changes to the adjustment layer without making changes to the underlying layer.  It also add a layer mask so that you can define the area of the layer below it that you want to be affected by the adjustment layer.

ADJUSTMENT LAYERS affects ALL of the layers below it by default.

TIP: You can have the adjustment layer affect only one layer by create a clipping path to the layer below it (See Clipping Mask). Also to have the adjustment layer affect only a PORTION of a layer, modify the include layer mask by painting with black or white.

There are several ways to create an adjustment layer:

1. Click or ALT+click the Create New Adjustment icon (half black and half white circle) at the bottom of the layer panel and select the type of adjustment layer you would like to create from the menu.  You have a host of options to choose from (Solid Color, Gradient, Patterns, Levels, Curves, etc.)

What can you do with layers:

1. Blend IT -- choose from a list of blend options in the layer panel to blend one layer pixels with that of another underlying layer. Blending layers create a "similated lighting" effect. Unlike filters where you can apply multiply filters to a single layer, you can only apply a single blend to two adjacent layers.
2. Select IT -- right-click on the image while the Move tool is select to move to a desired layer without having to use the Layer panel.
3. Link/Unlink IT -- click on the link icon at the bottom on the Layer panel to link or unlink selected layers.
4. Group IT -- click on the Create New Group icon at the bottom of the Layer panel  to create a group (or folder) so that you can organize related image together or to apply layer styles or blend modes to a group of layers. You can also select the layers and the select the New Group from Layers option to group the layers without having to move the layers into the group. You can also link groups,
5. View IT  -- click ALT + a selected layer eye icon to view just that layer.
6. Order IT -- drag selected layer(s) up/down the layer panel to change its stacking order. You can also CTRL + click the right/left square brackets. CTRL+SHIFT with brackets to move to Top or Bottom (but not below Background layer) or choose Layer>Arrange and one of the arrange option from the submenu.
7. Style IT -- click on the Add layer style icon (fx) at the bottom on the Layer panel to add a layer style (i.e., shadow, glow, etc.) to the layer (except Background layer) TIP: To make the object invisible but the shadow visible, set the opacity to 0%.
8. Duplicate IT -- drag layer to Create New Layer icon at the bottom of Layer panel.
   By dragging -- Hold down the ALT key and drag to create a duplicate layer while at the same time positioning it anywhere within the layer stack.
   From menu  or Right-clicking -- select Layer>Duplicate Layer...
   From keyboard -- Control J to duplicate above current selected layer
9. Delete IT -- drag layer to trash can icon in Layer panel or select Layer>Delete Layer)
   
10. Invert IT-- Choose Image>Adjustment>Invert with the layer mask thumbnail selected or select CTRL+I
11. Rename IT -- double click on the layer name to rename it.
12. Flip IT -- click on the layer to flip and select Edit > Transform > Flip Horizontal/Vertical from the menu.
13. Move IT -- To move multiple layers and to create a temporary linking of them, select the layers and move them using the Move tool. To create a more permanent linking, select the layer and click on the lock icon at the bottom of the Layer panel, then move them.

What you CAN NOT do with the Background (layer)?

• Move it
• Delete it (when it is the only layer)
• Use blend or opacity
• Create Layer mask

You can; however, convert a Background into a layer by double-clicking on the Background name and renaming it or

You can also convert a layer to a Background by choosing Layer>New>Background From Layer ath top of laye menu.