Adobe Photoshop - Basic Terms

Pixel A pixel is a single dot of color information in a digital picture. Anything you see on your computer is comprised of millions of these dots, packed so closely you can’t tell them apart. However, through the magic of Photoshop, I can show you an example.

This appears to be a regular picture of Chris Bosh looking weird. But if I zoom in on his eye…

It’s really nothing more than a collection of dots and colors That come together to form his eye!

Raster Adobe Photoshop is a raster-based program. Something defined as “raster based” means that the picture is comprised of a grid of pixels. Each pixel in the image has a color value and all together, the pixels show the image. Attempts to enlarge images in a raster based program means that the original pixels will increase in either size or number. A low quality picture will show its poor quality when these pixels are enlarged, as the data is being spread over a larger area and is, as a result, easier to see.

Resolution Resolution is the total number of rows and columns of pixels in an image. An example of image resolution is “1024x768” This means the image is 1024 pixels wide by 768 pixels tall. The same term is used for computer monitors. Resolution is also called: Dots per inch (DPI) Pixels per inch (PPI) These two terms are used like shorthand to assess an image’s quality. For instance, 72dpi is low resolution because only 72 pixels fit in an inch. 300dpi is good resolution because there are more pixels (300) per inch than the 72dpi example. With more pixels per inch, you can be certain that an image will enlarge better without looking spoopy.

Color Modes Photoshop can handle files in multiple different colors, depending on your needs. RGB – Stands for Red, Green Blue RGB are the three channels of visible light that we can see. All digital devices (Phones, tablets, computers, TVs) show you color in mixtures of Red, Green, and Blue. Values of color in RGB go from 0 (black) to 255 (white) Pixels will have three values, one for each channel (R, G, B)

Color modes continued CMYK is the color mode used for print. Cyan, Magenta, Yellow, Black In printing, CMYK mixes the four colors from above to make a color a printer can produce. Pixels will have four values, one for each channel (C, M, Y, K) CMYK should only be used in design when the product is intended to be printed. Colors are duller, the expectation is to be printed on white paper and enhanced by the brightness of the sheet. RGB is designed to have vibrant colors for digital displays like smartphones, tablets, and monitors, alternatively.

Layers Photoshop works in a concept called “layers” (This works pretty much exactly like you expect) You can place images on their own layers, and depending on the position of the layer in the stack, you can see through one image to the other below. When you start erasing from one picture to reveal the one underneath, you can do some pretty interesting things…

We’ll just put a picture of this what’s-her-name here on the first layer…

Add a picture of the… interesting-looking Ron Howard on top of her…

And with a just a few minor erases, we’ve made something that will haunt our dreams.

Compression A technique that reduces the file size of images. Compressed images are used on web pages to improve viewing speed and performance. Knowing compression is very important. Depending on how you use the image can mean the difference between an 11MB file and one that’s 303kb. (That’s 36 times smaller) Changing resolution is the most common way to resize an image, but compression comes from what you save it as. (GIF, JPEG, PNG, etc.)

Take a close look here… One side of this image is compressed, the other is not. Can you guess which is which? How can you tell?

Selections In Photoshop, you can use a variety of tools to select areas of a picture. A selection is an outlined area that contains all pixels within its boundaries. A selection can be simple, or complex. Using tools like the lasso, the marquee tool, or the magic wand. The lasso lets you draw a completely custom shaped selection. The marquee tool lets you make selections as squares or circles. (And ovals and rectangles) The magic wand selects all of a certain color in one click.

Selections (Continued) When an object is selected, a selection border appears around the selected area (left). When the object is deselected, the selection border disappears (right).

Aliasing Since pixels are square, aliasing occurs when attempting to create curves or diagonal lines. Since the curve or line is being represented by squares, it appears jagged. Below, aliasing appears on the left “A”. Notice how different the two look, as the other “A” on the left has been “anti-aliased”.

Anti-Aliasing Anti-aliasing is the smoothing of jagged edges in digital images by averaging the colors of the pixels at a boundary. Below, anti-aliasing appears on the rightside “a”. Instead of jagged lines, the hard edge seems to fade into lighter colors.

Opaque / Opacity Any part of your digital composition that is completely opaque cannot be seen through. In other words, opaque is the exact opposite of the word transparent. The amount of opacity an image is inversely proportional to the amount of transparency it has. If that confused you, don’t worry. Here’s an example: Since opacity is inversely proportional to transparency, something with 85% opacity is 15% transparent. (It adds to 100%) Something 60% transparent is 40% opaque.

Destructive vs Non-Destructive In Photoshop, two terms get thrown around to describe a process in terms of how it affects your document. Destructive processes make actual, physical changes to your pixels. For example, designing in RGB and then changing the document color mode to CMYK reinterprets the color values permanently. Erasing with the eraser is a destructive process. Making a selection and clearing it with the delete key is a destructive process.

Non-Destructive Options Non-Destructive options in Photoshop simulate processes or creates a temporary barrier between you and the actual pixels. Proofing (Via the VIEW menu) allows you to simulate color changes without actually making them. Useful to flip the switch back and forth and evaluate your color choices. Masking allows you to cover an area with an invisible shield that you can add to or restore from. Just like taping over the molding at the bottom of a wall you’re painting. Adjustment layers allow you to add effects like gradients and black-and-white filtering without actually affecting the composition.