Analogue - data stored in a continuous form.
Digital - data processed using binary numbers (0 and 1) through on/off impulses.
Scanner - an input device that digitises images, creating bit-mapped (those 1s and 0s again) copies that can be manipulated electronically. The graphics produced through the use of these applications can be divided into two primary groups or "graphic types," object oriented (vector) and bit-mapped (raster).
Object oriented
Graphics are often used for line drawings, logos or any image that requires smooth, crisp edges. One of the benefits of object-oriented graphics is that they can be enlarged, reduced or distorted without loss of detail or sharpness.
Bit-mapped
Graphics are usually picture or photographic type images such as those captured using a scanner. Bit-mapped images are made by "mapping" the image to an imaginary grid created by the scanning software. Colour or tint is applied to each square of the grid, producing an overall image. Unlike object-oriented graphics, bit-mapped graphics cannot be enlarged without affecting image quality. As the image increases in size, the squares of the grid increase in size, reducing clarity. It is important to plan for the final output size when scanning a bit-map graphic in order to have enough information, or detail, to meet the output requirements. Your service provider can provide specifications for scanning requirements. Bit-mapped graphics are usually larger files than object-oriented graphic files since more information is required to reproduce the image.
While graphics files are divided into two types - object-oriented (vector) and bit-mapped (raster) - there are many "file formats" used to produce graphic images. Two widely used file formats are TIFF (Tagged Image File Format) and EPS (Encapsulated PostScript). TIFF files are usually bit-mapped while object-oriented files tend to be EPS files. Different types of images, such as photographs, logos and line drawings can be imported into one assembly application for design and layout by using common file formats.
At the completion of the design and layout phase, all elements have been assembled into one file. This file may include both object-oriented and bit-mapped graphics saved in various file formats. The file is now ready to be raster imaged (bit-mapped) based on the requirements of the selected output device. A grid is established based on the resolution of the output device. All elements in the file, regardless of type or format, are bit-mapped creating an image, which can be reproduced by the output device. Digital Images can be produced from a wide range of output devices using various technologies. Liquid ink-jet, electrostatic, solid ink-jet, thermal-transfer and photographic are the primary technologies used today.
Here’s a brief introduction to several of the technologies:
Ink-jet
Drop on demand - ink is released by applying pressure to force a drop of ink onto the media as needed to create the image.
Continuous- ink is continuously under pressure forming a stream of droplets. The droplets required to form the image are channelled to the media, while the unused droplets are recycled.
Thermal- a gas bubble is created in the nozzle, creating pressure to force a droplet of ink onto the media.
Solid - ink is stored in a solid format, melted as needed and applied to media using methods similar to liquid ink-jet.
Thermal wax / resin transfer
Wax or resin is applied to a film carrier, usually in a roll format. The wax or resin is transferred to the media using heat. Each colour must be transferred individually.
Dye sublimation
Similar to thermal transfer, sublimation dyes are transferred from a carrier roll and applied through the use of heat. When a controlled amount of heat is applied, the dye is vaporised and transferred to the media.
Electrostatic
Special media is imaged with an electronic charge, which attracts toner particles. Typical electrostatic printers image each colour individually.
Spray jet
Individual ink colours are applied directly to the media through a spray nozzle. Digital images can be applied to paper, vinyl, fabric, plastics and many other materials. Depending on your specific requirements, your service provider can help you select the best output device.
Finishing
Using special media, inks and/or laminates, images can be produced which withstand sunlight and most weather conditions. Also, adhesives are available which provide the opportunity to apply digital images to various surfaces. You'll find digital images on buses, planes, buildings, ceramic tiles, textiles and just about any surface imaginable
