Illustration Resolution Requirements
Resolution is measured in dots per inch (DPI). Width is the dimension of interest for paper publications because books and magazines have fixed column widths whereas height is easily adjusted to the individual illustration. Line art and photographs are handled in different ways.
|drawings and graphs||1200 at 100%||EPS, Illustrator, Freehand|
|photos and halftones||300 at 100%||TIF, GIF, JPG, PICT, Photoshop|
Difference Between Offset Printing and Computer Imaging
The final paper book is produced with the offset printing process, which produces images of better quality than possible on a computer screen, in a photocopy, or from a 600 DPI laser printer. Video frames that look great on a computer terminal can look grainy, jagged, or pixelated in an offset printed book because that process reveals deficiencies that our eyes compensate for when we look at a computer screen.
ASNT's graphics personnel realize that some images are computer-captured files and lack the resolution that can be reproduced in this book process. But many authors do not use the optimum resolution when capturing video frames; maybe they don't remember to change their software preferences or settings or don't know how to. They could also make a better result if they sent ASNT the best hard copy output that they can. In some cases, ASNT can get the best images by scanning the hard copy printouts from the contributors' color laser printers.
Calculating DPI for Photos
The final size is important because DPI is meaningful only for the file at its final published width at 100 percent. First, assume that ASNT will publish a photo at a typical column width of 18 picas (75 mm or 3 in.). Other figure widths are possible, depending on the publication. (It helps to refer to previous volumes or issues and to ask ASNT staff.)
Photographs other than line art should be at least 300 DPI at 100 percent of the final published size (about 18 picas, 75 mm, or 3 in.). Note that an image that is 360 DPI at 1 in. wide will be only 120 DPI after ASNT scales it to fit a column width of 3 in. A 600 DPI figure is not high resolution in any practical sense if it is the size of a postage stamp!
Line art scanned or submitted as bit mapped images (TIF, GIF, PICT, JPG) should have a resolution of 1200 DPI at 100 percent of 3 in. This resolution guideline does not apply to line art that is vectorized (EPS, Illustrator, Freehand).
Hard copy line art that is scanned to produce a TIF file should be scanned at the LINE ART setting, not GRAY SCALE. Gray scale scanning will result in a larger kB file and lines that are pixelated or dirty. To ensure best results, it is best to send the original line art to ASNT and let ASNT scan it at optimum settings for the final size and project.
If you are ready to send an electronic graphics file:
Question: All my images are embedded in a Word document. Should I extract them and save them for ASNT individually in another format?
Answer: Only if smaller files are needed to get them to ASNT - for example, by floppy or by e-mail. E-mail servers sometimes choke on attachments greater than 1 MB, and a Word file with many embedded objects can easily be larger than 2 MB. Please check to see if you have copies of the images BEFORE they were embedded in Word. ASNT can extract images out of your Word file but would prefer to get an earlier version as close to your original as possible.
Question: Why can't ASNT use my Word file? It looks OK to me.
Answer: With the exception of some conference proceedings and paper summaries, ASNT performs all layout and formatting to ensure consistent appearance and to provide the best resolution in the offset printing process. To achieve this level of publishing quality, ASNT exports files from Word before reformatting them in layout programs and converting the finished files to PostScript language. Like other professional publishers, ASNT can use Word files as sources but does not publish documents in Word.
Question: I have a JPG file. Should I convert it to TIF before I give it to ASNT?
Answer: No. ASNT can do that and would prefer to get something as close to your original as possible.
Question: My file is in color. Should I convert it to black and white?
Answer: ASNT will do that as needed. If final publication is to be in black and white, then converting it yourself will let you check to see that color-coded information is not lost in the black and white version. However, remember that ASNT may still use a color illustration for an electronic medium, such as Web or CD-ROM.
Question: If my original source is a printed source (a book, brochure or magazine), should I scan it and send you the scan?
Answer: Before using copyrighted art, be sure to get permission to use it with a Request for Permission form. Published images have usually been "screened," that is, converted into images consisting of many tiny dots. To avoid moire patterns, pixelation and other problems, it is good to send the original and let ASNT scan it. If this is not practical, contact ASNT staff for guidelines specific to your scanner and image.