Sign & Digital Graphics

February '19

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S I G N & D I G I T A L G R A P H I C S • February 2019 • 45 Compression Some formats compress files so that they take up less storage space. TIFF (Tagged Image File Format) saves all of the characteristics of PSD or PSP and decreases the file size using compression scheme called LZW, named after its cre- ators, Lempel, Ziv and Welsh. Saving a file to TIFF format (see Figure 2) provides the option to somewhat reduce the file size and maintain the edit- ing capabilities of the software. Because LZW maintains the quality and reduces the file size it is referred to in computerese as a lossless compression scheme. JPEG JPEG is an extremely efficient format for archiving a flattened image or saving it for publication to the web. Named for its creators, Joint Photographic Experts Group, JPEG format can reduce file size to the extreme. Be careful though! When saving images, JPEG format discards crit- ical information as it organizes data into clusters. The quality of the image can be compromised. Because of its propensity to compress images by losing data, JPEG is referred to as a lossy compression scheme. Fortunately, when you save an image as a JPEG a dialog box enables you to determine its quality (see Figure 3). I recommend that you choose the highest quality setting whenever possible. Low- quality JPEGs can produce some pretty dismal-looking images, compromising color and contrast and creating extrane- ous artifacts (as shown in Figure 4). PDF PDF (Portable Document File) is a universal format developed by Adobe Figure 2: Saving a file to TIFF format provides the option to reduce the file size using LZW compression. Figure 3: The JPEG dialog box enables you to deter- mine the quality of the saved image. Figure 4: Low-quality JPEGs (right) can compromise image quality. Systems in 1991. A file saved as a PDF can be composed of images, editable text, interactive buttons, hyperlinks, embed- ded fonts, and even video. PDF file format is used for publish- ing product manuals, portfolios, eBooks, flyers, job applications, presentations, brochures and numerous types of other documents. Because PDFs don't rely on the software that created them or any specific platform or hardware, they look the same without regard to the device or platform on which they are opened. Most users rely on Adobe Acrobat reader, a free software program, to view P D F s, however they can be opened, edited and saved back to PDF format in Photoshop and Microsoft Word among many other programs. Less Common Formats Native formats—J P E G , T I F F and PDF—are among the most commonly used graphic formats, but there are oth- ers that you're likely to encounter. E P S (Encapsulated Postscript) (Figure 5) for example, is used to save vector-based documents or to transfer vector-based objects and paths from one software program to another. Figure 5: EPS is used to save vector-based documents or to transfer vector-based objects and paths from one software pro- gram to another.

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