At the top of Photoshop’s Layers panel you will find two clusters of icons. The topmost cluster filters layers, allowing you to quickly hide layers, revealing only the ones you need to see. The other locks the active layer(s) in different ways.
These buttons provide a fast way to protect different aspects of layers. Some are more intuitive than others. Hover your cursor over each to see its name.
Lock Transparent Pixels
This lock protects the transparent parts of a layer. If you paint or apply a filter, only the nontransparent pixels are affected. Translucent pixels retain their level of transparency too. In the following illustration, I painted across this layer that contains opaque and translucent pixels.
A filter, such as a blur, will affect only the “inside” details: the edge would not get blurry, for example, but the opaque details would. You may transform the layer (e.g., move or scale it).
Lock Image Pixels
This lock prohibits filters, painting, and anything that would alter the details of a layer, but like the previous lock, it does allow you to scale and do other transformations. Disallowed tools will show a forbidding cursor.
This prevents moving or transforming layers, but not filters or painting. This lock is the most similar to a Background’s state.
Sometimes when we create new artboards, and very often when we create frames with the Frame tool, one or more existing layers are affected.
Applying the fourth lock to layers prevents their automatic enclosure in frames and artboards. Luckily, we can apply locks to multiple layers simultaneously. In this example, the locked layer remains free after drawing with the Frame tool. If I unlock that layer, it would get captured by the frame.
This prevents all editing of a layer and is thus the most intuitive. You may still move the layer up and down in the layer stack, but its content is fully protected. Because it’s the simplest to use and understand, it’s the one I use the most.
When layers start to add up, it becomes harder to find the one you need to edit. Filters hide all but the layers you specify. Or you may wish to more easily edit all layers of a kind. For example, you may need to change the phrasing of all the text layers in a document. Filtering by Kind and then clicking the T icon will help ensure you’re seeing all the text layers and nothing else. Below, I’m filtering to show only adjustment layers.
If a filter type offers more than one icon, you may combine them. Thus, I can filter to see both shape and adjustment layers. I cannot, however, filter to see pixel layers that have been clipped: I can filter to see pixel layers (filter type Kind) or clipped layers (Attribute), but since they’re different types, I can’t do both at once.
Attribute filters are powerful in that they can be both positive and negative. That is, I can choose to see all the locked layers or unlocked ones, or layers with or without layer masks. Here are a few more types:
Name Filters by text in the layer’s names.
Effect Shows only those layers with a specific effect, like a drop shadow or bevel.
Mode Shows layers with a specific blend mode.
Color Useful if you’ve applied color labels to layers. This doesn’t refer to color fill layers.
Smart Object Lets you filter by Smart Objects with specific criteria. Although you can filter by Smart Object with the Kind type of filter, this one lets you specify linked or embedded, or linked ones whose content needs updating or is missing.
Selected Shows layers you have highlighted, probably for the purpose of filtering to see them.
Artboard In a document with more than one artboard, this will restrict the view to the layers in only one at a time.