Understanding Photoshop is a biweekly column that takes an in-depth look at how digital photographs are built and manipulated. It is a college-level course in plain english for free at Photofocus. To learn more see this article.

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Let’s continue our overview of Photoshop’s interface. It’s important to understand the key panels and elements that you need to work with to get results. This article serves as an overview. We’ll dig deeper into each in later lessons.


Let’s continue to work with the file Eagle.psd.

02_LayersIn Photoshop, a layer can contain artwork and transparency information. This allows you to combine (or composite) multiple images into a new piece (such as a postcard or advertisement). Originally, Photoshop did not have layers. You could open a picture to process it, but that was about it. However, over time the demands placed on Photoshop by its users led to its evolution. As Photoshop moved beyond a mere touchup tool, the flexibility of layers emerged to meet the demand. Photoshop now has several special layer types including adjustment layers, shape layers, and fill layers. By isolating discrete elements to their own layers, designers can make several changes and freely experiment with their design.

Without sounding like a zealot, layers in Photoshop mean everything to a user. You will spend much of this book (and your early career using Photoshop) getting comfortable with layers. With that said, always leave your Layers panel open while you work (press F7 to open it); this is where most of the action takes place. The Layers panel is like the steering wheel of a car.



Previously, we looked at the different image modes that a computer graphic could occupy were discussed. In the Channels panel you can view the individual components of color. The brighter the area in the individual channel the more presence there is for that color. Lets look at a simple example of an RGB graphic:

  1. Choose File > Open and open the image called RGB_Overlap.psd. You should see red, green, and blue circles overlapping one another. The overlap has also created new colors: red + green = yellow; blue + green = cyan; red + blue = magenta; and red + green + blue = white.
  2. Activate the Channels panel. By default it is docked with the Layers panel (just click on its name and the panel will switch to display Channels). If you don’t see it, choose Window > Channels.
  3. Look at the individual channels; you’ll see a definitive area for each color. Notice how the full circles are visible (and white) where there is 100% value of each channel.
  4. Close the document by choosing File > Close.

Fully understanding Channels unlocks a wealth of image-processing power. Harnessing colors individual components is difficult at first but well worth the effort. You’ll delve much deeper into Channels in a later lesson


02_PathsAlthough Photoshop is known as a raster-editing tool (because of its several pixel-based functions), it does contain several vector tools as well. Vectors use lines that are defined by math equations; as such, they can be scaled indefinitely and always remain crisp.

Several of Photoshops vector tools can create paths, which are useful for complex selections. You can create a path with the Pen tool. By clicking around an image, anchor points are created, and then Photoshop connects the dots with vector lines. Paths can also be created using the vector shape tools. Use the Paths panel to select the path you want to update.

Paths are a useful way to save a selection to use later. In the example of this file I’ve saved selections so I can make isolated adjustments to the birds beak, body, and eye.


02_AdjustmentsOne of the most common tasks in Photoshop is making adjustments to images to fix tone and color. Photoshop offers an Adjustments panel to provide easy access to the most common nondestructive adjustment commands. The adjustments are grouped into three categories:

  • Tonal controls. Use these controls to adjust Brightness/Contrast, Levels, Curves, and Exposure in a nondestructive fashion.
  • Color controls. Use these controls to adjust Vibrance, Hue/Saturation, Color Balance, Black & White conversion, Photo Filter, Channel Mixer, and Color Lookup properties.
  • Creative/Advanced controls. These controls are special purpose adjustments and include Invert, Posterize, Threshold, Gradient Map, and Selective Color.


If you’re using an Adjustment layer, you’ll need to control how it affects your image. Additionally, adjustment layers (and optionally all layers) can have a mask applied to control the opacity for the layer. Photoshop uses masks to obscure parts of an associated item. In fact, you can apply a mask to a layer, a vector, or a filter.

Both Masks and Adjustment layers are controlled using the Properties panel. To view the panel, just select an adjustment layer in an open image. Here you’ll find as buttons across the top to switch between the two. You’ll see multiple masks in use in the sample document (Eagle.psd) to isolate the effects of color correction. .


Photoshop CC offers precise control over masks including the ability to adjust their density and edges. Masks are a useful way to erase parts of a layer nondestructively, which allows for future changes. They can also be used to isolate an adjustment to only parts of an image.