Labels:text | screenshot | font | number | printing OCR: manipulation programs to convert your design from RGB to CMYK or other color spaces Depending on how you plan to use an image and how demanding you are regarding 0 Both Adobe and Quark, for instance, provide information in their product manuals for image quality, sizing and scaling issues will vary in degree of importance and in im- working with ICC profiles in their applications. plementation. Occasionally results, even with careful planning and calculation, can be surprising and apparently defy reason. Here's an example: PhotoDisc images are routinely - On a Macintosh system, copy the PhotoDisc profile from the ColorGuide disc (in the sized and scaled up to appear on large billboards. The results? Despite calculations that PhotoDisc Source Profile folder) to your ColorSync folder (in your System folder). On a tell you that this shouldn't be the case, they end up looking fine (this is in part because Windows system, copy the profile to your hard drive (c:\Windows\System\Color). the viewing distance is normally around 100 yards). What we use Raster devices To create profiles at PhotoDisc, we use the Heidelberg CPS system along with a Monitors are commonly set at 72 to 75 pixels per inch (ppi) and are referred to as raster GretagMacbeth Spectroscan spectrophotometer. devices because they display with scan lines. Many desktop proofers also print with raster data - ink-jet printers, dye-sublimation printers and copiers usually print without half- tone screens and range from 200 to 1,400 ppi. (Some new large-format printers can get Step 3: Size and Scale Images Properly away with clearly reproducing images at a resolution as low as 50 ppi.) This allows the raster device at each end of the process (monitor and printer) to communicate using the same language (pixels per inch) when image-quality concerns come into question. Pixels, halftones and image quality Establishing a ratio For many people, understanding the relationship between pixels and halftone dots is Traditional printing and halftone proofing devices use a halftone computed by establish- as confusing as understanding the relationship between Euclidean geometry and ing a ratio between pixels per inch and lines per inch (Ipi). To maintain high quality this subatomic particle theory. Plenty of controversy revolves around sizing and scaling ratio is 2:1; in other words, for high-quality printing at 150 Ipi the digital file should be at images and how different raster image processors (RIPs), which convert images from 300 ppi. Despite this, acceptable results can be achieved all the way down to 1:1 - prima- pixels to halftone dots, work with different programs. rily with less critical work on newsprint and other inexpensive paper. 18 19
