Alpha channels are stored alongside colour channels within Photoshop files but do not affect the final image printout. Instead, they store information that is helpful to you, such as saved Masks.
Anti-aliasing
Moving pixels around can cause undesirable jagged edges to appear, where edited pixels have not blended smoothly together. Anti- aliasing refers to the process of smoothing out these jagged edges for a more natural look.
Brush
Brushes enable you to paint on Photoshop images with colour, other bits of images and pre- defined patterns. They mimic real brushes in that you can alter the size, hardness and texture in order to achieve the effects you want.
Colour channel
There are three colour channels in all colour images: red, green and blue. Each one contains information specific to that colour. Photoshop enables you to alter each channel independently, making it possible to reduce grainy blue skies without affecting the rest of an image, for example.
Feathering
Softening the edges of pixels in a selection, so that they will blend smoothly when moved elsewhere. Photoshop does this by only partially selecting some of the pixels around the edge of the selection.
Filter
One of Photoshop’s preset tools that applies an effect to an image (or a selection within the image). Examples include sharpening, blurring, creative
and artistic filters. You’ll find a complete list by clicking in the Filter menu at the top of the Photoshop window.
Font
A commonly used term used to describe the typeface you are using. For instance, Times New Roman is a font where all the letters look fairly formal. In Arial, however, all the letters are far simpler looking.
GIF (or .gif)
A type of image file format best suited for producing simple images for the web. Examples include logos, banners, buttons and anything made up of only a few flat colours.
Greyscale
An image is greyscale if it contains no colour information. Almost all digital camera files, for instance, will be in colour. But you can turn them into black and white with many fine gradations of grey, from within Photoshop by turning them in to greyscale images.
Image size
This refers to the physical size of an image. For instance, a photograph you are working on may be 20x15cm. This matters most when you come to printing out the image.
JPG (or .jpeg)
A type of image file format that gives a desirable combination of small file sizes and good quality photo reproduction. It is commonly used in digital cameras to store the images that you take. The small files sizes also make it ideal for the web.
Layer
Layers containing effects or bits of images can be stacked on top
of the original image layer (the background) in order to change the appearance of the image. Layers do not directly affect the layers beneath them, in the same way as a blurry piece of glass placed over a photograph does not actually affect the photograph – in both cases, it is the appearance that is changed, leaving the original untouched.
Marquee
The flashing dotted outline that surrounds a selection. You’ll also see it referred to in some places as ‘marching ants’.
Navigator
In Photoshop’s default screen layout, the Navigator is positioned in the top-right corner and gives you access to the whole image, even if you are currently zoomed in to a specific part. The red box within the Navigator image denotes the area that is currently on screen; you can move around your image by clicking and dragging the red box around the Navigator image.
Resolution
A measure of how many pixels make up an image. A resolution of 300dpi (dots per inch) is recognised as the minimum if you’re intending to print your images.
Selection
Any part of an image which you select with Photoshop’s tools, shown by a marquee around it. You can then work on certain parts of an image, or remove then without affecting the rest.
Slices
These are special kinds of selections for web page design. An image can be split into segments or slices, and Photoshop creates an
HTML file, plus separate image files, for each slice. The web browser then reassembles the slices in their original position to give the appearance of a single image.
Thumbnail
A small, ‘thumbnail-sized’ version of an image. You’ll find them in folders of images and in Photoshop’s File Browser – Because they’re smaller than a full size image you can browse through them more quickly, which makes finding the file you’re after far easier.
Pixel
An abbreviation for ‘picture element’, it is essentially a tiny dot of colour on screen. Most images are made of up millions of pixels, which combine to make an image look seamless. Zoom in very close on an image, however, and you can clearly see these individual pixels.
PSD
Photoshop’s own file format, which preserves things such as layers and channels. If you’re editing an image file, it’s sensible to save it as a PSD, in order for the changes you have made to remain editable when you next open it.
Tool Options bar
When a tool is selected, the corresponding Tool Options bar automatically appears at the top of the Photoshop window, giving you access to various options, including such things as Brush Sizes and Feathering.