Introduction to Photoshop

Photoshop is one of those programs that many vow to learn, but few actually master. Part of the problem, I believe, is a lack of a fundamental understanding of the system and how it fits into the bigger picture of graphics and design.

With that in mind, please consider this a tutorial aimed at readers who have little or no knowledge of Photoshop, and would like to have the holes in the picture filled in.

Raster vs. Vector

One of the things I run into the most in my career is people confusing the purpose and function of raster and vector graphics. Photoshop's specialty is raster graphics manipulation. It has limited vector capability, but if you're looking to do vectors, what you really want is Illustrator.

Quite simply, raster graphics are made up of pixels--that is, points of color that when assembled, appear to be a picture. Raster graphics are resolution-dependent, meaning if you try to make them larger than they started, they lose quality because the computer has to guess what it should look like.

Vector graphics are made up of instructions that describe the image rather than plot it out dot by dot. For example, a circle could be described as "circle(x=1, y=1, r=3, red)." This could tell the computer to draw a circle at coordinates 1, 1 with a radius of 3, and a fill color of red. The major advantage vectors have over rasters is demonstrated here, because the math makes them resolution-independent. A multiplier can be applied to the instructions to make that circle appear any size desired without losing an ounce of integrity. That is the power of math.

Why don't we just use one or the other? Each has its place and function. Raster graphics are best for images like photographs, where immense detail is needed to create the complex color patterns that are found in our physical reality.

Vector graphics are more commonly found in the print industry, where resolution-independence shines. A printer can print a vector image with as much detail as it is physically capable of, whereas it can only print a raster graphic with as much detail as is provided in the map of tiny pixels. Magazine and newspaper advertisements are almost always created in a vector format, sometimes including images in compliment.

Document Color Modes

When creating a Photoshop document, you can choose between a number of color modes. The most common color mode for images viewed on computer screens is RGB, which stands for Red, Green, Blue, the way color is broken down into numbers by the computer. Other modes include CMYK (Cyan, Magenta, Yellow, Black), commonly used in the print industry, Indexed, which is used in GIF and other limited palette formats, and LAB, which I am mostly unfamiliar with. For our purposes, you'll want to stick with RGB.

Layer Stacks

Each Photoshop document is made up of one or more layers that can each contain pixel data. These layers are all displayed in the layers palette. There are also special types of layers for paths and shapes (vector lines), and adjustment layers. Adjustment layers provide a safe way to alter several of the image's attributes without committing to the changes permanently.

Layers are stacked from the bottom up, so layers with pixels in the same spot as a layer beneath it will cover that layer up. Wherever there are not pixels, the layer is transparent, that is, you can see other layers beneath it.

You generally work on one layer at a time. New versions of Photoshop let you select and manipulate multiple layers at the same time by shift- or control- clicking them in the layers palette.

Layer Groups

Layers can be grouped into folders (groups) for better organization in a document. You can expand or collapse groups of layers in the layers palette in order to show or hide layers you aren't working on to keep things less cluttered. Layer groups also perform some advanced functions we won't be discussing in this tutorial.

The Toolbox

One of the main points of your interaction with Photoshop is the toolbox. In it, you'll find all the main tools you'll use to paint, select, move, and otherwise manipulate layers or pixels. Almost all of the toolbox buttons have keyboard shortcuts, and I recommend learning as many as you can, as it will save you much time in your work.

Pixels vs. Paths

As mentioned before, there are several types of layers in Photoshop. In normal layers (pixel layers) you work with pixel data directly. In shape or path layers, you're working with a vector path. Vector paths can be quite useful for certain purposes, such as document scalability, large blocks of color (saves disk space over filling it with pixels), and stretching and reshaping capability. Most of your layers, however, will likely be pixels. If they end up being paths, you might want to take a look at Illustrator, as it may do a lot more for you.

Output formats

After you're finished creating your pixel masterpiece, you can save the document in any number of formats. Photoshop's PSD format is the best if you're planning on working on it later. I always keep the original PSD file of everything I make in case I decide to make a change to it later.

The output option I use most is called Save For Web. This feature allows you to create JPG, GIF, and PNG files that are optimized to minimize file size while maximizing quality. Always use this feature if your destination is the Internet.

You can also export your vector paths as an Illustrator file, which is useful in some cases as well. Other output formats include TIFF, which is good for the print industry, TGA (Targa), which offers a full alpha channel (transparency information), and regular old Bitmap (BMP), which I do not recommend at this point in time. JPG has far exceeded the popularity of BMP in recent years due to its comparatively tiny file size.


Thank you for reading, I hoped you learned some of the fundamentals of Photoshop and can use them to better understand the world of digital imaging!

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