Photoshop Basics

Photoshop can be a little intimidating for photographers. That’s understandable – it’s a big application with lots of complex controls and menu choices, and with a long history supporting complex workflows. But, if you can learn just a little bit of Photoshop, you can improve your post-processing workflow and do things in post that are difficult or impossible in Lightroom.  

In this article, I’m going to take you on a tour of the basic concepts in Photoshop. The intent is to provide a roadmap for how Photoshop is organized and what the possibilities are, so you can experiment and learn. I hope you’ll see that it isn’t as complex as it might appear.

What is Photoshop?

This seems like a goofy question, but bear with me as I’m going to outline some important concepts. There are two key things you need to know.

Photoshop is a raster graphics editor. That’s a fancy way of saying that it is an app designed to help you edit the individual pixels of your photos. All of its tooling is built around manipulating those pixels. This is contrast to a vector graphics editor, like Illustrator. A vector graphics editor allows you to manipulate and edit shapes. That’s useful because if you have drawn your company logo or something in terms of shapes, you can scale it to any size without losing data. Vector graphics are later “rasterized” or converted to individual pixels. For the most part, you don’t need to worry about this distinction, other than to know that Photoshop does have some limited vector tools that I’m not going to cover here. 

Photoshop is also a layered graphics editor. This means that you work with your content as a stack of layered images. Imagine a juicy cheeseburger that has a bun, patty, cheese, tomato, and more. The burger consists of a bunch of individual layers that combine to form a finished whole. That’s a little like how your photos are put together in Photoshop, but instead of cheese and tomato, your layers might consist of different effects filters, healing bad pixels, applying adjustments, and so on. We’re going to explore the layering concept in more depth below.

How does Photoshop differ from Lightroom?

Photoshop and Lightroom are both designed to work on raster images (e.g. photos) but they have some pretty significant differences when it comes to post-processing. Lightroom also has an extensive catalog management system and other organizational tools that Photoshop lacks, but we’re going to focus on the tools for editing images here.

One big difference is that Photoshop is optimized entirely around powerful editing tools for one photo at a time. You can make very complex edits to photos and even construct entirely new photos from the components of existing ones, but it’s difficult to do this in bulk. By contrast, Lightroom has some editing tools, but it sacrifices complex editing tools in favor of bulk tools that allow you to make edits to many photos at the same time. This distinction is blurring a little over time as Lightroom gains more complex tooling.

Perhaps the biggest difference though is that Photoshop is based on layers, and Lightroom is not. Layers are the magic that makes Photoshop so powerful for photo editing, but they also add some complexity. Lightroom has a version of layers with brushes and similar tools, but they lack the complexity of the layering system in Photoshop that makes it so powerful.

Understanding layers

With that, let’s get right into layers in Photoshop and why they are important.

I want to return to the burger example. Imagine our burger has these layers, which I’ve presented here from top to bottom instead of bottom to top, as is customary in Photoshop:

• Bun

• Lettuce

• Tomato

• Cheese

• Patty

• Bun

Imagine you are looking straight down on the burger from above. All you would see is the top bun of course. If you didn’t know any better, you might think you were only looking at a bun.

Now let’s remove the bun, exposing the lettuce. The lettuce doesn’t exactly fit the shape of the rest of the burger. Looking straight down on the burger from the top, you see a lot of lettuce, but you also see some areas where the tomato either is not covered by the lettuce, or where the lettuce is so thin that you see some red of the tomato peeking through.

Now remove the lettuce. The tomato definitely doesn’t fully fit the shape of the burger, and moreover has holes in it where the cheese is clearly visible, but also the innards of the tomato that create a translucent area where the cheese is partially visible. In fact, if you put the lettuce back, on you’ll probably find places where neither the lettuce nor the tomato obscures the cheese. 

This burger is like the layers in Photoshop. Like the burger, each layer has something it adds to the photo, like contrast, exposure, color, etc. Each layer affects the stack in different ways. Some layers have some transparent areas, and some layers don’t cover the layer below them at all. Unlike the burger though, you have full control over what these layers do and how they affect the other layers. 

This is an extremely powerful capability because it allows you to precisely control adjustments to only very specific areas of your image. That is, in Photoshop, you add a layer to do what you want, and then use a mask to control exactly where it appears. The mask governs which areas of the layer apply to the stack, and by how much. This is very different than in Lightroom where you generally apply an adjustment to the whole photo, or to a very rough part of the photo using a brush. 

Some examples of things you can do with this capability in Photoshop:

• Add contrast to a very small area of a photo.

• Adjust the brightness of only the red parts of the image.

• Desaturate only the darkest parts of the image.

• Apply a filter like a Gaussian blur to only one tree.

• Blend two different images together shot at different times.

• Superimpose a person from one image into another image and make it look natural.

Parts of layers

Conceptually, layers have four parts you need to care about:

• The layer itself

• A mask

• Blending mode

• Opacity

You can do anything with a layer that you can do with the base image in Photoshop. You can paint, paste parts of another image, draw vector shapes, add adjustments, and more. Think of it as just a collection of pixels that you can manipulate.

The mask is a black and white image that accompanies the layer and is the same size as the layer itself. It determines which parts of the layer will contribute to the overall image. Pure white pixels cause the corresponding layer pixel to contribute 100% to the image. Pure black pixels cause the corresponding layer pixel to contribute 0% to the image. Of course, you can paint in all the grayscale colors in between, which is where things get interesting and allows you to make really precise and fine adjustments.

Every layer has a blending mode. A blending mode determines how the layer’s pixels affect the layer below it. The default is Normal, which simply uses the mask to determine how to apply the pixels. But there are other interesting blending modes you can use. For instance, the Lighten blending mode only takes the pixel from this layer if it is brighter than the layer below it. Other blending modes exist for different purposes, and a great way to get a feel for them is to experiment in Photoshop.

Every layer also has an opacity. This is simply the transparency applied to every pixel in the layer. 100% opacity means that each pixel fully contributes to the image, 0% means none of the pixels are visible, and the values in-between of course allow you to find some middle ground.

Where this really gets interesting is when you combine all of these things together. For instance, a red circle in the layer with a mask that only exposes half of the circle, with a blending mode like Multiply, and an opacity of 75%. If this gets you excited for the possibilities, great! But, if it has you worried, know that this is an uncommon type of scenario for most photos, and you can very safely use just the basics or parts you understand without needing to over complicate things.

Speaking of over-complication, there are many, many more options for layers you can use beyond just these four. I’m not going to cover them here though.

The Layers palette

Your view of the layers that compose your images is the Layers palette, made visible by choosing Window -> Layers. The Layers palette allows you to see the layers in order in your image, make adjustments, create and delete layers, and more.

There are a couple of common things you can do from here that I’ll mention:

• Hide and show a layer. Click the eyeball icon next to the layer to hide or show it. You can also click and drag on the eyeballs from multiple layers to hide and show several at a time.

• Add a new layer. Click the small icon at the bottom of the palette that has a half-filled circle in it and pick the layer type. The new layer will appear.

• Delete a layer. Click on a layer and press the Delete key on your keyboard, or click the trash can icon at the bottom of the palette. You can’t delete the last layer in the document, however.

• Reorder layers. Click and drag a layer to move its position relative to the others.

• Add a layer mask. Click the small icon at the bottom of the palette that’s a square with a circle in the middle. A new layer mask appears. If you have made a selection, the selection will be used to create the mask.

Adjustment layers

An adjustment layer is a special kind of layer that applies some type of configurable effect to the image. Unlike a normal layer, adjustment layers don’t have the “layer itself” part of the layer. That is, there are no pixels to paint. Instead, they apply an adjustment to all of the layers below them.

For example, consider the Brightness/Contrast adjustment layer. As the name implies, this layer allows you to configure the brightness or contrast of the image. If you add such a layer and bump the brightness up, it will have the effect of making the layers below it brighter.  

Using adjustment layers, you can perform precise, non-destructive edits on your images. Simply add an adjustment layer, tweak the effect, and adjust the mask. The alternative is to make the adjustment with a tool directly onto your image, which might achieve the same effect, but makes it hard to undo if you make a mistake.  

As of this writing, there are 16 adjustment layer types available in Photoshop. You can see them by choosing Window -> Adjustments. To add one, just click on its icon, and a new layer is inserted into the Layers palette. You can also add adjustment layers from the bottom of the Layers palette by clicking the half-filled circle and choosing the adjustment layer you want. 

When you add an adjustment layer, in place of the usual layer pixels, you’ll get a symbol that represents the adjustment in the Layers palette (for instance, a sun icon for the Brightness/Contrast layer). Double clicking this symbol will open the layer properties, where you can modify the adjustment.

It is well worth your time to experiment with these layers to see what they can do. You can perform entire edits with nothing but adjustment layers to your image.

Tools

Now I want to switch gears and talk about the tools that Photoshop offers. Tools are used to directly manipulate the pixels on an individual layer, for instance by painting a color onto the layer. Tools are considered destructive in that they directly modify pixels, but by applying tools on a new layer, they can be made non-destructive since you can always delete or hide the layer.

Tools are shown in the Tools palette that’s usually docked on the left side of the window. The icons for the tools can be confusing, but if you hover over them with your mouse, you’ll get a tooltip that explains what the tool is. Note also that some tools are grouped with other tools, and you need to click and hold on a tool to see the options. 

There are a ton of tools offered by Photoshop. I’m not going to cover them all, but I’ll cover the important ones here.  

• Move. This tool is used to move a part of your image to another location. You make a selection, then click and drag to move it.

• Marquee and Lasso. These tools are used to create selections in various shapes.

• Select. These tools are used to intelligently create selections. Quick Select tries to find the edges of an area for a precise selection. Magic Wand tries to select similar adjacent pixels. The new Object Selection tries to use Artificial Intelligence to pick the most prominent object in the area you draw.

• Crop. This tool is used to crop the image to the selected area. Note that this tool affects all layers, not just the selected one.

• Eyedropper. This tool is used to sample a color from your image and insert it onto the color palette.

• Healing. These tools provide a way to heal and clone out areas in your image. This is a common tool to use in photo editing to remove unwanted sticks and branches, red eye, and other problems. Because these tools are destructive, it is usually best to duplicate the main layer of your image (right click the layer -> Duplicate) and work on that layer in case you make a mistake.

• Brush. These tools allow you to paint onto your image using the color selected. There are a million different brushing options available from their own toolbar, but mainly you’ll be interested in the size of the brush, the opacity of the brush, and how hard the edges are (feather).

• Clone Stamp. This tool allows you to clone one part of the image into another. Like Healing, it is destructive, so work in a separate layer.

• Hand and Zoom. These tools don’t change your image, but allow you to change the view of the image by panning or zooming into it. By far the most common way to use these tools is to use their keyboard shortcuts. Press and hold the spacebar to pan in your image. To zoom, press and hold Cmd or Ctrl, and then + or – to zoom in or out. You can zoom to 100% in your image by pressing Cmd/Ctrl and 1, and zoom to fit by pressing Cmd/Ctrl and 0.

Selections and masks

The last concept I’m going to talk about is creating selections and masks. This is a really powerful capability that is used commonly in photo editing and is worth your time to master.

A selection is a part of your image that has been selected (for lack of a better term) for editing. Selections appear as marching ants around a portion of your image. Any edits you make only apply to the selected area, until the selection is changed. For instance, if you use the rectangle marquee tool to draw a rectangular selection on your image, and then use a black brush to paint, only the area within the selection will be painted. You can use selections to constrain the operation of destructive tools to only a certain area. 

Selections have another purpose too, and that is to create masks. If you have a selection, you can use it to create a mask for a layer. When that happens, the selection disappears, but you can continue to manipulate the mask in the layer with the tools you use to manipulate the main part of the layer. Once you have the mask, you can manipulate the layer as you see fit, and only the masked part will apply to the image. Creating a mask from a selection is an important task in photo editing.

There are a variety of ways to create selections in Photoshop. Some of the more common ones for photo editing use are: 

• Tools. The Marquee and Select tool groups offer several ways to create different types of selections. There are several other tools that also create selections that I haven’t covered here.

• Select menu. This menu offers some large-scale options like select all, select none, select inverse, and similar. It also offers some finer grain tools like selection by color range or areas in focus, along with an AI-powered subject selection tool. There are also tools for manipulating an existing selection.

• Channels palette. This palette, which sits alongside the Layers palette, shows you relevant masks in your document and allows you to create selections from them. You can also create saved selections on the Select menu which appear here.

• Plugins. Several 3rd party actions and plugins work to create selections. A popular plugin type is luminosity masks, which create selections based on the brightness or tonal range of pixels in your image.

Once you’ve made a selection, you will usually want to convert it to a mask. There are several ways to do that in Photoshop:

• Add a new layer. Choose Layer -> New Layer. The selection will become the layer’s mask.

• Add to an existing layer. Choose the layer you want to add the mask to, and click the small rectangle with the circle in it at the bottom of the Layers palette. The selection will become that layer’s mask.

• Add an adjustment layer. Adding any adjustment layer with a selection will cause the adjustment layer to be added with a mask that corresponds with the selection.

If you have a mask and want to go back to a selection, this is easy too. Simply hold down Cmd or Ctrl, and click on the mask. You’ll see the familiar marching ants appear, indicating a selection.

You can also modify masks directly using tools. Simply click on the mask in the Layers palette and a white box will appear around the mask in the Layers palette. Then pick your tool (such as brush) and start drawing. Note that the main image will still be visible, but you can show only the mask by holding down Option or Alt and clicking on the mask to toggle it on and off. 

Wrapping up

There are a lot of areas of Photoshop that I didn’t cover here. It’s an enormous program, but you can still get value out of it by just sticking to the parts you know. The areas I have covered here are the most important, foundational parts that you need to know to make progress. Focus on those and you might be surprised at how much you can get done. 

Photoshop is best learned by example. Spend time with an image or two in Photoshop with no goals other than to experiment and see what you can do. For a structured example, my Milky Way book takes you through editing Milky Way images from start to finish, and is a great way to learn Photoshop. In the book, I also dive deeply into many of the topics above, especially the all-important issue of creating masks and selections.

Don’t be afraid to try different things to see what you can produce – you will probably surprise yourself!