A drop shadow is a term used in computer graphics. It refers to a computerized drawing placed underneath or near an object on the screen. This graphic simulates a shadow effect, so it is typically a dark facsimile of the original object placed on a light background.
Drop shadows are primarily used for stylistic effect. They make an otherwise flat object appear somewhat dimensional by giving the illusion that is it raised above its surroundings. Further realism can be achieved by giving the shadow soft edges or by making the shadow darker in certain places. The former effect is often achieved via a method known as a Gaussian blur, whereas darkening can occur through alpha blending. A blending technique is particularly effective if the foreground object is somewhat translucent.
These flourishes were one of the first effects popularized in computer design. They became widely used because drop shadows were a means of adding some style to text or objects without having to significantly change any other aspect of the document. Some unusual variations of the traditional form included checkered backgrounds, floating backgrounds, and forms with slight color variations known as gradient fills.
Many aspects of computer graphics utilize the drop shadow image. Websites may utilize drop shadows in order to draw attention to certain written passages or images, or as an overall background effect. Drop shadows can operate on both graphics and words in individual computer documents, making these objects more legible and clear if set against a plain background, or particularly a cluttered background. Many graphical user interface components like icons also contain drop shadows. Since these components allow computer users to directly interact with what is presented on a screen, it is usually important that they are highlighted in some manner, such as with a drop shadow.
Encoding a drop shadow into a document must usually be achieved via a style sheet language. These are the marks and directions that an individual uses to create the look of a computerized document. In general, certain symbols and marks, known as mark-up language, are placed around text or instructions, and these symbols and marks will direct a program to create a certain effect on-screen, like drop shadows. One of the most used forms of style sheet language is Cascading Style Sheets (CSS).
Photo editing software often has the drop shadow as an effect option as well. Editing techniques typically involve adding layers of revisions and effects to an original picture. When using drop shadows in software, the user is often presented with a menu that guides him or her through the process. These menus allow different aspects such as the shadow's color and angle to be fine-tuned.