Raster and Vector Images

Digital Imaging Digital imaging is the use of images that can be altered using a computer for varying outcomes. They can be natural (such as a photograph) or artificial (such as a drawing created on Photoshop). Digital imaging is often used to communicate information.

Raster Images Raster images are created by altering the colour of pixels and mapping them out, they are also called bitmap images. Their quality is dependent on resolution. They are manipulated by changing pixels not shapes.

Vector Images Vector images are not made of pixels, instead they are created using a series of paths. These paths can be used to form geometric shapes and lines. They do not loose quality when resized because both their appearance and size are defined by algorithms.

Raster Image Vector Image

Advantages Disadvantages

Raster •  Ideal for photos that involve varying tones and complex colour. •  Can be used to store real world images, such as scanned paintings • Raster formats translate well to dot outputs, such as printers • Can be edited easily, either by one individual pixel at a time, or a group of pixels.

•  They are dependent on resolution so it is hard to resize them without altering image quality •  The file size can be very large if the image contains many colours. •  Raster images do not scale well, shrinking the image removes pixels while increasing the size replicates pixels, in turn decreasing the quality.

Vector •  Can be used for 3D imaging •  Can easily be made larger or smaller without loss of image quality •  It is a flexible file format, can easily be changed into a raster image or another type of vector.

•  Cannot be used to store very complex images •  The appearance of the image can vary from application to application due to the individual application’s interpretation of the image • Reconstruction of the image can take longer than a raster because it’s elements must be redrawn in sequence

  Graphic Interchange Format   Gifs are mainly used for web

graphics, such as navigation buttons.

  Can have up to 256 indexed colours, because of this they are relatively small files and are easily transmitted on the web.

  Lossless image file format   Can be animated (as seen in

the example) because of it’s layered format.

Explanation When To Use This Format

JPEG Stands for ‘Joint Photographic Experts Group’. A compressed file format. No colour limit. JPEG’s have a lossy format. Raster image.

For photographs and natural images, web use

GIF Stands for ‘Graphics Interchange Format’. A compressed file format. Indexed colour, with a maximum palette of 256 colours. Permits transparency. Can be animated

Web use, small images, icons

TIF Stands for ‘Tagged Image File Format’. Uncompressed file format. Can handle quality ranging from 1-bit to 24-bit. There are 50 variations of the format after it being developed in the 1980’s. A very versatile format.

Storage and interchange of large files such as high definition photos. Can be customized to store any peculiar type of data.

  http://www.techterms.com/definition/vectorgraphic

  http://www.sharpened.net/glossary/definition/jpeg

  http://www.sharpened.net/glossary/definition/gif

  http://www.techterms.com/definition/tiff   http://www.groups.esa.edu.au/course/view.php?

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