Understanding the digital technology design world.
By Jim Cotton
The road from design concept to final printed element can be long and confusing. No matter the end product, art and design can take many turns. Today, all art interrelates through the raster image processor (RIP) with the output device—usually a printer—in a digital format.
Image creation. Before digital, art was photographically imaged onto printing plates. An artist’s 2-D creation was photographed by a copy camera using color filters to separate the four process colors (cyan, magenta, yellow and black). These separations were shot in continuous tone and then contact printed with halftone screens, which allowed for varying shades of ink lay-down. The screens were exposed one at a time. Their combination on the printer gave us the color range we still see in small format today.
The scale of the manual separation process was limiting. It took the development of digital scanning technology to unharness the printing world from its small format origins.
Today, scanners and digital cameras record an image in a bitmapped, digitized form, creating a continuous-tone image depicted by a series of squares, called pixels. The process electronically records a color for each pixel scanned on a grid, and determines where the pixel is placed. Examples of this “tagged image” format are TIFF (tagged-image file format), GIF (graphic interchange format), and PNG (portable network graphics).
Image manipulation is now done by altering pixels in computer applications, such as Photoshop. In the past, manipulation was done with photographic printing (dodging, masking) or by an artist. Artists worked primarily on a “dye-sublimation” paper print with separate layers of dye. They could add or subtract imagery, such as extending a background or altering the color of an object.
Digital was finally able to go large format—and then grand—with the invention of mathematical algorithms that were able to increase the resolution in pixels per inch, and therefore the scale, without degradation of image. Files that contain pixels, or dots per inch (dpi), have a finite resolution. If a low-resolution image is enlarged without using a software program that increases resolution, the printout will contain distortion.
File formats. Graphic design computer programs have been developed to draw shapes, shades and patterns. This “vector format” creates a series of instructions that form the graphic out of whole cloth through a digital graphical representation using straight lines to construct the outlines of objects. Vector files contain instructions on how a computer generates an image, not the image itself. They are therefore resolution independent and don’t have the constraints of TIFF files when enlarged. These instructions can be scaled to any size as they don’t contain finite pixels.
File compression formats, such as JPEG (joint photographic experts group), were created to make files smaller while maintaining quality. This allowed for easier transmission and less data storage capacity. Design files need to be created within the specifications of the output device, usually a digital printer. People often confuse a JPEG (a tagged image compression format) with a PDF (portable document format), which can be read in most programs and always in Adobe Acrobat Reader. However, both formats provide file compression. A JPEG can be a compressed Photoshop file, but not a vector file (Illustrator).
Applications. Files or graphic documents that contain all of the design elements should ideally be created in a page layout program, such as Adobe InDesign or Quark Xpress, because the working file size is much smaller than the final output file. Smaller files are easier and quicker to work with when doing routine activities, such as opening and saving. EPS (encapsulated postscript) and PDF files containing a photograph or illustration are created so that the contents can be placed as a graphic in a page layout program. When the overall design is finalized, an EPS file is usually created to interface with the output device.
A variety of graphic files can be saved as PDF Acrobat files, which can be viewed on most computer platforms without utilizing the program it was created in. The PDF function usually can be found in the file menu under “Export” or “Save As.” However, unless the PDF is saved with editing capabilities enabled, no color or other corrections can be made by the print provider. Most print providers require that all native files and placed images be included in submitted material and will supply their specifications readily. The latest version is Acrobat 9. The Pro version allows for comments to be added by both the sender and the receiver, which is ideal for proofing, making corrections and approving content. Portfolios can be created that have multiple pages and features, like form generation.
These are some of the basics of design and technology. Exploring these various programs and formats will be enlightening and rewarding, as these tools are now driving the imaging industry. They are the current lexicon and can’t be ignored.