 | | | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Prepress GuideGraphicsTwo types of graphics are used in creating digital pages whether they are color, grayscale or black and white: raster and vector. Raster Graphics: These are bitmapped images and are resolution dependent. Vector Graphics: Graphics created in a postscript drawing program and saved as EPS files to be placed on the page. These are not resolution dependent and can be resized without loss of image quality. Raster GraphicsBitmap ImagesPhotographs and other original art captured digitally with a scanner are raster, or bitmap images. These images can then be placed in a page layout or brought into a paint program like Adobe Photoshop for modification. Work created in a paint program and some clip art are bitmap images. Bitmap images are resolution dependent, meaning they cannot be enlarged or reduced without image degradation. Correctly calculating the needed resolution will save disappointment and rework later. For more information about resolution, see Scanning. In bitmap images, each pixel is “counted” in the file regardless of color value (white pixels are counted the same as black or colored pixels). The higher the file resolution, the greater the number of pixels there are to count and process, resulting in greatly increased files sizes and imaging time. Cropping extraneous images in the creating application and accurate resolution save both disk space and production time. Linking Graphics Vs. Storing Or Embedding Another way to save disk space and time is to “link” graphics instead of storing or embedding them in the application program. When store or embed features are used, the layout application actually saves the entire graphic again inside the file. This means that there will now be two places on your hard drive where the entire graphic exists, and the layout file will become very large and cumbersome. Another problem with storing and embedding graphics is that they are permanently placed as is, and our prepress department cannot make adjustments for press-gain. When graphics are linked, we are able to make these adjustments if necessary to the linked graphic, and the layout application automatically updates them. If you choose to store or embed graphics anyway, please remember to include the original graphics along with the application file in case they need to be adjusted. For more information about linking, please see Creating Pages. Vector GraphicsArt elements created in applications such as Adobe Illustrator are vector graphics and are resolution independent–they can be resized as needed without loss of image or quality. Vector graphics are a collection of instructions for the imagesetter or laser printer, and have relatively small file sizes, making them ideal for creating logos, maps, and elements that will be used in a variety of sizes. Truetype fonts are also an example of vector graphics. File size is determined by the complexity of the art and not by physical size or resolution. Even though these graphics generally do not have to be adjusted for press-gain, it is still best to link them to your application program instead of embedding them, and then include the original graphic along with your job.File FormatsMany different formats for saving files exists with a variety of different uses, but as a rule only TIFF (Tagged Image File Format) and EPS (Encapsulated PostScript) are suitable for high resolution imaging. Some other formats often seen are PICT, PNTG, BMP, and WMF. These should be converted to TIFF or EPS files at the proper resolution. The GIF and JPG formats are used almost exclusively for internet applications and are not suitable for print purposes.Prepress Guide IndexPreflightCompatibility & Fonts Creating Pages Creating Covers Scanning Graphics Working With Color PDF Files Electronic Transfers Proofs |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Home | Links | Site Map | Careers | Our Company | Services | Prepress Guide | Client Resources | EarthCare Initiatives | News | Contact Us
p. 734.429.5411 f. 800.677.BOOK e. info@bookprinters.com Copyright © 2011. McNaughton & Gunn Inc. All rights reserved. Web site design by Connection Graphics
