Output Devices:

Hardcopy images are images that may be taken away from the computer and communicated to your audience without any computer mediation. This may be done in several ways, but the basic idea is that any kind of medium that may carry an image is a candidate for hardcopy. Each of these media contains its own issues in terms of its capability and how you should prepare your images for the medium.

We will discuss many hard copy technologies.

Before explaining the actual hard copy devices it is significant to understand the various factors which shall affect the image quality attainable by these devices. Some of the factors are explained below.

1. Dot/Spot Size : Diameter of a single dot.

2. Addressability : Number of individual dots/inch that may be created. It differs in horizontal and vertical directions. It may be calculated in x direction as the reciprocal of the distance among centres of dots at addresses (x, y) and (x + 1, y). Likewise, it may be defined for y, i.e. (x, y) and (x, y + 1). Inter-dot distance is the reciprocal of addressability.

3. Resolution : It is the numbers of distinguishable lines/inch that a device may create and white line may be distinguished by observers. Once we have understood the terminology defined above we may further see their effect in the image quality. For instance, if dot size is greater than the interdot distance, then overlapping smooth shapes may be created. However, at the same time this is to be remembered that smaller dot size allows the viewing of finer detail. We may also see that the resolution is associated to the dot size and may not be greater than addressability. In this case, it is apparent that resolution is also dependent on the cross-sectionals intensity distribution of a spot. Spot having sharply delineated edges yields higher resolution than the spot whose edges trail off.

After going through the above terminology it will easy to understand now the working of various output devices and how it is going to affect the quality.