Unit 35 - Graphic File Formats and Applications
Computer graphics are pictures and movies created using computers - usually referring to image data created by a computer with help from specialized graphical hardware and software. Computer graphics is responsible for displaying art and image data effectively and beautifully to the user, and processing image data received from the physical world. The term computer graphics has been used a broad sense to describe almost everything on computers that is not text or sound. It is the representation and manipulation of image data by a computer and the various technologies used to create and manipulate images.
Vectors describe the shape of an object as a series of points connected by curved or straight lines, represented as a mathematical formula. Vector graphics are often used for designs of business logos which can be scaled down to card size or scaled up to billboards without losing any detailing or shape. File formats compatible with vector graphic are: EPS, AI, PDF, SVG, DXF
Computer software programmes that use vectors graphics are: Adobe Illustrator, Serif Draw Plus, Inkscape and Xara.
The Advantages of Vector Graphics are:
Scalable, can be any size without loosing quality.
Smaller file sizes than raster graphics and are more easily transferred and loaded in the web.
Faster upload and download speed than raster graphics. Even a larger vector image will transfer and load faster than a smaller raster image.
Vector uses lines and therefore makes it easier to incorporate more and sharper detail into images.
The Disadvantages of Vectors Graphics are:
Vector files cannot be easily used to store extremely complex images.
Thin lines in vector may disappear if reduce in size too much.
Vector graphics are time consuming and generally require more skill compared to raster graphics.
Photographs cannot be taken as vector images.
Bitmap graphics are digital images created or captured as a photograph, as a set of pixels in a given space. A raster is a grid of x and y coordinates on a display space. The most common use of bitmap images are photographs. Every digital photograph taken is an interpretation of light and colour translated into a bitmap image as pixels. File Formats compatible with bitmap graphics are: JPEG, PNG, BMP, TIFF
Computer software programmes that use bitmap graphics: Adobe Photoshop, GIMP, Coral Photo Paint, Adobe LiveMotion
Advantages of Bitmap Graphics:
Bitmap files may be easily created from existing pixel data stored in an array in memory.
Pixel values may be modified individually or as large groups by altering a palette if present.
Bitmap files translate well to dot-format output devices such as printers.
Disadvantages of Bitmap Graphics:
They can be very large in file size, particularly if the image contains a large number of colors. Data compression can shrink the size of pixel data, but the data must be expanded before it can be used.
They do not scale very well. Upsampling and downsampling occurs in the pixels during rescaling which can change the whole look of an image.
A metafile is a piece of graphical information stored in a format that can be exchanged between different systems or software. Metafiles can store multiple types of data. This commonly includes graphics file formats. These graphics files can contain raster, vector, and type data. A common use for these files is to provide support for an operating system's computer graphics for examples Microsoft Windows uses Windows Metafile, and Mac OS X uses PDF.
Types of Metafile are: PICT, WMF or EMF (enhanced), EPS, CGM, PDF, CDR, SVG, WPG, RTF