Reprographics, printing and output: HSC Industrial Technology Graphics Technologies

What this dot point is asking

Producing a drawing or design is only useful if it can be reproduced and output reliably. NESA expects you to describe the reprographic and printing processes used to output graphics, and to explain colour, resolution and file management. This industry-facing content covers how graphics move from screen to printed product, and it appears in the written paper and matters whenever you produce hard copy of your Major Project folio and presentation drawings.

What reprographics covers

Reprographics is the reproduction and output of graphics: taking a drawing, design or document and producing copies, whether one print or many thousands. In the graphics industry this spans everything from printing a single architectural plan to mass-producing packaging and publications. Understanding output processes lets you choose the right method for the quantity, quality and budget of a job.

Output devices and plotting

Individual and short-run graphics are output on a range of devices:

• Inkjet and laser printers produce everyday documents and presentation prints, laser for crisp text and inkjet for colour and photos.
• Plotters output large-format technical drawings, architectural plans and posters that exceed normal printer sizes.
• Wide-format printers combine plotting and high-quality colour for large presentation graphics.

These devices suit one-off and small numbers, where setup cost matters more than per-copy cost.

Printing processes for volume

High-volume reproduction uses dedicated printing processes:

• Digital printing prints directly from a file with no printing plates, so it is fast, economical for short to medium runs, and allows each copy to differ.
• Offset printing transfers ink from plates via a rubber blanket to the paper. It has a high setup cost for making plates but a very low cost per copy, so it is economical only at high volume, and it gives excellent quality for books, packaging and magazines.

The choice between digital and offset is mainly a question of quantity, the same setup-versus-volume trade-off seen across manufacturing.

Colour: RGB and CMYK

Colour behaves differently on screen and in print, which is a common source of error:

• RGB (red, green, blue) is the additive model used by screens, which create colour by emitting light.
• CMYK (cyan, magenta, yellow, black) is the subtractive model used in printing, which creates colour by absorbing light with inks.

A design that looks vivid on an RGB screen can print duller in CMYK, so files are converted and proofed before printing. Understanding the two models explains why colours must be managed for accurate output.

Resolution and quality

Resolution is the amount of detail in an image, measured in pixels or dots per unit. Too low a resolution prints blocky or blurred; high resolution prints sharp but produces large files. Images for print need higher resolution than images for screen. Matching resolution to the output, sharp enough to print well without files larger than necessary, is part of preparing graphics for reproduction.

File formats and management

Graphics are stored in different file formats for different purposes: vector formats that scale without loss for drawings and logos, raster formats for photographs, and exchange formats such as PDF for sending finished documents. Good file management keeps work reproducible: sensible naming, version control, backups and recording which format and resolution suits each output. Disorganised files lose work and cause printing errors, so managing them is a real professional skill.