Vector graphics consist of discrete objects which can be selected and manipulated independently of the rest of the drawing. By contrast, a Photoshop image is one continuous whole consisting of a matrix of pixels. Making selections in a bitmapped image is therefore much more complex and difficult than simply clicking on an object as you would do in a vector drawing. In fact, selections are such a big deal in Photoshop that there is a whole menu dedicated to selection options and techniques: the Select menu.
Having succeeded in making your selection, Photoshop allows you to save it and load it back at a later date. If the selection has sharp edges, you will probably save it as a vector path. In the Paths panel (Window – Paths), choose Make WorkPath from the panel menu. If you may want the selection to contain feathering and other soft edge effects, you are best to save it as an alpha channel. To do this, simply choose Save Selection from the Select menu.
Selections are required within an image for any number of reasongs. Perhaps we want to cut out a product or person and place them on a different background. Perhaps we want to blur part of an image to add emphasis to the remainder.
The selection itself is a recognised element within Photoshop and can be manipulated independently of the pixels they include. Selections almost make you forget the absence of objects within bitmapped images. Once part of an image is selected, it can be targeted and manipulated in such a way that the pixels inside the selection can almost be treated as an object.
Making selections is often a painstaking operation; and so Photoshop allows you to build selections gradually and contains a number of sophisticated tools for modifying them. One of the simplest techniques is to add to or subtract from an existing selection. This can be done either by using modifier keys (hold down Shift to add or Alt to subtract) or by clicking on icons to enter Add or Subtract mode. Any selection made using one of these methods will take into account the pixels that are already selected.
Once you have mastered a few basic techniques, selections become less like hard work. Photoshop is extremely consistent in the use of modifiers, so it doesn’t matter which selection tool you are using, the same techniques are always used for adding to and subtracting from a selection.