Layers

If the layers tab is not visible in your photoshop project then it can, like all windows, be brought up by going to "Window > Layers". Alternately you can press "F7" as a shortcut key.

Here are the key factors to remember when working with the "layers" tab.

  • There are two possible preview images that can appear in the layer browser. The left will always show either the image preview, a shape icon, or an adjustment layer icon depending of if the layer is a raster layer, a vector object, or an adjustment layer. The preview images to the right of that will always be a mask (if a layer has no mask you will only see the image preview).
  • The "lock" icons, easy to see as they are to the right of the word "lock", allow you to stop various qualities of a layer from being edited. If you have a layer, such as a reference image, that you NEVER want to be edited then it is wise to enable the padlock symbol to stop all editing of that layer. Even the most advanced of Photoshop user will still find this function useful.
  • You can change the size of the layer preview image by either Right-Clicking the empty area below the layers and selecting a new image size or else click the panel options button in the upper right of the layer panel, selecting "Panel Options" and then changing the size in the new window.

Most of the icons that run along the bottom of the layer panel have self-explanatory tool tips and repeat commands that can be found from the main menu options.

From left to right you can find the layer lock toggle (for moving two or more layers together), the layer effects options (see below), the vector mask option to quickly add a fully revealing vector mask, the create adjustment layer mini-menu, and probably most importantly the "create folder" option, "create new layer" option and "delete currently selected layer" option.

The create folder option is especially usefuly as this will make a folder that allows you to organize your layers into a tree structure so that you don't have to look at what might end up being dozens upon dozens of layers.

Basic keyboard commands for Layers

  • Right-Clicking a layer preview image will bring up a mask-specific context menu that allows for deleteing layers (and a few of the other commands right below this one).
  • Holding ALT and Left-Clicking & Dragging a layer preview icon (and releasing it within the layer palette window) will allow you to duplicate the entire layer.
  • Holding Ctrl while Left-Clicking a layer will select all non-zero pixels (pixes with more than 0% opacity).

Blending modes

In Photoshop, changing the blending mode of a layer is as simple as selecting the desired mode from the blending mode drop down, found in the top section of the layers tab.

Above you see the main layer options of the Layers palette. The red arrow is highlighting the drodpown to change the blending mode which is currently the default "Normal". The green arrow highlights the Opacity option which can be used to change the transparency of a layer. Below that are the lock options and the fill opacity (see Layer Effects).

TIP: Always remember that if you want to preview layer blending modes quickly you DO NOT have to click and select each layer blending mode. You can just make a selection from the blending mode drop down once and then use the up and down arrows on your keyboard to cycle through the list!

Also remember that blending modes in Photoshop can be applied to layer groupds (folders). This will apply the blending effect across all layers within the group.

Editing Locks

This is not really an extension of the layer blending options but the various "locking" modes do appear directly below the blending mode option. The locking modes come in 4 types and allow you to "lock" a layer to prevent editing of a particular property. The primary use of this is to prevent accidental editing of certain layers in more complex projects.

  • The transparency lock prevents you from changing the transparency of a layer by either deleting existing visible pixels or filling in transparent pixels. For instance if a particular pixel has an opacity of 25% then no amount of painting or erasing will increase or decrease this opacity level. The color of the pixel may still be changed.
  • The painting lock takes the transparency lock one step further and prevents alteration of both the transparency of a layer AND the colors of it. The layer may still be moved however.
  • The move lock option allows editing of the pixels on a layer but prevents the layer from being moved with the Move Tool (or via the "Ctrl-Click" shortcut).
  • The full lock mode (the pad lock symbol) will prevent any and all editing of a particular layer. Literally the only operation that can be used on a fully locked layer is to delete it.

None of these locking options will prevent a layer from being affected by an adjustment layer or other effects that work *above* the locked layer.

Layer effects

Adobe Photoshop has a set of unique effects referred to as "Layer Effects". These various effects include things like strokes, overlays, and drop shadows. Finding the "Layer Effects" window is slightly awkward however as the way to open it is to Right-Click on a layer (in the title area) and select "Blending Options".

The real strength of these effects is that they are procedural and constant. In other words they are applied and update automatically whenever you make a change to the layer on which they are seen. Change the visible area of the layer and the effect changes to match. Change the opacity of the layer and the effect changes within (although helpfully you can even change the layer opacity separately than the effect opacity).

Here are a few of the more popluar effects.

Stroke

Stroke applies an outline of even width around the perimeter of a visible area of a layer. It is not a vector shape (even if the original layer it is applied to is a vector shape such as a text object) so you can not edit the width of it easily. The only change you can make to it, aside from the color, is whether or not the stroke falls along the inside, outside, or evenly over the edge of the original image.

Drop Shadow

The infamous drop shadow. It used to be that to create a drop shadow you would have to 1. duplicate a layer, 2. blacken the duplicate, and 3. blur the duplicate. And then with every edit to the shape of the original layer repeat the process to update the drop shadow layer. With the "Drop Shadow" layer effect this is all automated.

Drop shadow of course refers to the effect whereby a shape seems to be casting a shadow on a surface behind it. This effect can greatly enhance the appearance of "depth" within your image but, like most things, is best used subtly. Too harsh of a drop shadow will simply appear as a blurry stroked line on one side of your image.

Overlay options

There are three kinds of overlays within the Layer Effect options. Each of them accomplish the same thing in different ways. They fill in the entire visible area of a layer, not unlike the paint bucket tool, covering the original image in the process.

"Color" overlay is imply a solid color, "Pattern" allows you to fill the layer with a pattern (and change the scale of the pattern in the process) and "Gradient" allows you to fill the visible area with a gradient much in the same way the gradient tool works. With the gradient option you can move the gradient on the main canvas by simply clicking and dragging on it while the Layer Effects window is still active.

Handling layer effects

Keep in mind that the workings of some of these effects may change based on whether you've applied the effect to an individual layer or to a group containing layers. For isntance the size of a Gradient Overlay effect will default to the size of a single element if applied to a single layer and to the entire canvas if applied to a folder containing several layers.

Basic operations concerning Layer Effects are as follows...

  • You go directly to an effect from the layer panel. Just Right-Click the layer effects section of a layer (at least one must be present) and select the effect to go to in the context menu.
  • Layer effects can be temporarily toggled on or off by Left-Clicking the eyeball icon next to the effect (the icon next to the line "layer effects" will toggle all effects for that layer).
  • Layer effects can be copied between layers by holding the "Alt" key and Left-Clicking & Dragging an effect entry from one layer to another.
  • At any time you can change the opacity of the "Fill" via the layer palette options shown at the top of this page. This will allow you to change the opacity of the original image before effects are added, hence giving you the possibility to isolate and show the effects without the original image.

Masks

Masks can be made in a few different way.

  1. Press the "add a mask" button at the bottom of the layer palette window (a white square with a dark dot in the center).
  2. Through the "Layer" drop down menu at the top of the screen.

Let's look at the different kinds available within Photoshop.

Raster masks

Most masks default to a raster mask (this is what you'll get if you use the "add a mask" icon on the layer palette.

For more control of what type of mask you want and how it should be made instead choose "Layer > Layer Mask" from the main drop down menu. From there you have several options.

  • Reveal All: This option will add a pure white mask to the current layer, making the entire layer VISIBLE.
  • Hide All:This option will add a pure black mask to the current layer, making the entire layer HIDDEN.
  • Reveal Selection: Only the area WITHIN a current selection will be white / visible within a newly created mask. All non-selected areas will be hidden.
  • Hide Selection: Only the area OUTSIDE a current selection will be white / visible within a newly created mask. All non-selected areas will be visible.
  • From Transparency: This option will make a new mask which is similar, but not exact, to the transparency values of the currently selected layer. Useful if you want to transfer the existing transparency of one layer to another.

Vector masks

To create a clipping mask in Adobe Photoshop all you have to do is select the "Vector Mask" option when going through the "Layer" dropdown menu.

To create shapes within a vector mask just make sure that you are in "path" mode when you have either the shape tool or the pen tool selected.

Just as you can use options like "reveal" or "hide" selection when making a new raster mask you can choose the "from path" option to

Clipping masks

Clipping masks are different than the other two types of masks in that they don't use unique geryscale image to hide parts of the image. Instead they actually use a second layer, raster or vector, and the transparency of that second layer.

There are two ways to create a clipping mask.

  1. Right click on the layer (the label area) you want to be masked off and select "Create clipping mask" from the context menu.
  2. Hold down the Alt key and move the mouse to the thin line *between* the two layers you want to act as the mask and masked. When the cursor changes to a square with a bent arrow near it Left-Click to make a new clipping mask.

Below is a quick example of how clipping masks work.

The layer window (Adobe Photoshop) and the resulting (normal) image.
The layer window (Adobe Photoshop) and the resulting image. In Photoshop specifically this arrangment shows the top layer ("Red") as a clipping mask.

In this case the green circle is acting as a mask for the red circle above it, but while doing so remains completely visible.

This function is ideal for adding shading and highlights to any object. Adding a specular highlight is as simple as painting a lighter area and turning it into a specular highlight above the layer of the object you want to add the highlight to.

Basic keyboard commands for Masks

Here are some keyboard shortcuts that are useful to remember when working with masks in Photoshop.

  • Right-Clicking a mask will bring up a mask-specific context menu that allows for deleteing masks (and a few of the other commands right below this one).
  • Holding Alt while Left-Clicking a mask image will make the mask visible and editable on the main canvas. Alt-Clicking the mask preview again will revert the canvas to normal.
  • Holding Shift while Left-Clicking a mask will disable the mask without deleting it (you can also do this by right clicking the mask and selecting "disable"). Shift-Clicking the mask preview again will revert the mask to normal.
  • Left-Clicking & Dragging a mask will allow you to move it from one layer to another.
  • Holding Alt while Left-Clicking & Dragging a mask will allow you to duplicate it from one mask to another.

Alpha channels

Alpha channels are not shown in the main layer palette window. You have to look in the channels palette just as you would for the red, green, and blue channels. If the "Channels" palette is not immediately visible you can show it just as you can any palette by selecting "Window > Channels".

Keep in mind that not every image will have an alpha channel. If you don't see the "alpha" channel listed in the channel palette then the image doesn't have one.

A new alpha channel can be made by pressing the "new channel" icon at the bottom of the channel palette window (the white page icon that looks similar to the "new layer" icon in the layer palette window).