NCERT Book Class 12 New Age Graphics Design Digital Imaging and Printing

Graphic designers work with visual images, either for print media or for digital media. With the advent of computers, most of the graphic designer’s work is being doneusing computers. From graphical point of view there is a vast difference between images on paper such as drawings, sketches or photographs and images that you see on the screen of the computers. Images that are created, manipulated and displayed using computers are called digital images. Digital images are different from images drawn or painted on paper in many ways.

Types of Digital Images
There are two major categories of digital images: raster images and vector images. When images are stored in a computer in the form of a grid of basic picture elements called pixels, then these images are called raster images. The pixels contain the information about colour and brightness. Image-editing programmes can replace or modify the pixels to edit the image in various ways. The pixels can be modified in groups, or individually. There are sophisticated algorithms to achieve this.
On the other hand vector images are stored as mathematical descriptions of the image in terms of lines, Bezier curves, and text instead of pixels. This is the main difference between raster and vector images. However, this difference is responsible for the development of two major categories of graphic technologies namely: Raster Graphics and Vector Graphics. Therefore, the image-editing software used by the practicing graphic designers falls under one of these categories.
Since the Vector images are in the form of mathematical descriptions of the basic components of an image, it is easy to modify and manipulate them as well as transform them into Raster images. Vector images are easily scalable to any resolution. Major problem is that though vector images are mathematically precise many a times a graphic artist feels that the graphic quality is compromised. Raster images can also be manipulated and modified in various ways but transformation of a raster image into a vector image requires sophisticated computational algorithms. Raster images are comparatively more precise visually.

Digital Image Editing
Graphic designers frequently use both the types of digital images. There are tools to convert images on the papers into digital images. These devices are called scanners.
Such digital images can be further modified or manipulated digitally. There are software programs to create, modify and manipulate digital images. Such programs are called digital image editors. There are digital image editors for two dimensional image processing as well as three dimensional image processing. Using digital image editors, a variety of operations on the images are possible. Some of the common operations are discussed are as follows:

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