Save yourself from design errors in printing 3

Grayscale images

• File formats: Avoid file formats like PICT, GIF or BMP which were never meant for design purposes.
• Highlight and shadow dots:
  • The clearest point in grayscale images should not consist of pure white but should have at least a 2% dot in it. Acceptable exceptions are headlights of cars or specular highlights (small light reflexions on a shiny surface) for which it is no problem if they are “blown out”.
  • The darkest area of the images also shouldn’t consist of pure black. For 150 or 175 line screens, it is customary to use a 95 percent gray for the shadow dots. For newspaper printing, a 5 percent highlight dot and 80 percent shadow dot is not uncommon.
• QuarkXPress and TIFF: When placing TIFF images in QuarkXPress (Mac or PC) make sure to never have the background color of the picture box set to “none”. This avoids problems with staircasing (so-called jaggies) at the edges of the image.
• Resolution: Make sure images have the correct size and resolution while scanning them. The final resolution of black and white pictures should be (screen ruling x scale x 2). The “2” is a quality factor that can vary between 1.6 and 2.5 depending on your quality needs and the subject of the image. So if you scan a photograph and want to enlarge it 300 percent in the layout application and your publication is printed at 85 lpi, the image should be scanned at (85 x 3 x 2) or 510 dpi.
• Size: Never enlarge images more than 20 percent in your layout application. It will reduce the resolution of the images and lead to an effect called staircasing. Reducing images too much will lead to a loss in sharpness and contrast.

Color images

• File format: Avoid PICT, WMF or BMP images. The layout application may support these formats but their proper conversion to PostScript or PDF data is never guaranteed.
• QuarkXPress and TIFF: When placing TIFF images in QuarkXPress (Mac or PC) make sure to never have the background color of the picture box set to “none”. The image below shows what can happen if the background is set to ‘none’: either there is staircasing (jagged edges) at the edges of the image or white areas within the image simply vanish.
• Resolution: Make sure images have the correct size and resolution while scanning them. The final resolution of colour pictures should be (screenruling x scale x 2). The “2” is a quality factor that can vary between 1.5 and 2.5 depending on your quality needs and the subject of the image. So if you scan a photograph and want to enlarge it 300 percent in the layout application and your publication is printed at 150 lpi, the image should be scanned at (150 x 3 x 2) or 900 dpi.
• Size: Never enlarge or reduce images more than 20 percent in your layout application. Enlarging them will lead to pixelization and staircasing. Reducing them too much will lead to a loss in sharpness and contrast.
• Colorspace: Not all workflows can handle RGB or indexed images properly. Check with your trade shop or printer to see whether they support non-CMYK color modes.

Drawings

• File format: Save drawings made in vector drawing program such as Adobe Illustrator, Freehand or Corel Draw in the EPS format if they are to be used in a desktop publishing program like QuarkXPress or PageMaker. Avoid other formats like PICT or CDR. For Illustrator, you can use .AI files for inclusion in InDesign pages.
• Corel Draw lens effects and tiles: Avoid extensive use of lens effects in Corel Draw. They create big PostScript files, don’t always print as they appear on screen or won’t print at all. A possible work-around is to convert the objects that use lens effects to bitmaps. This will make them easier to RIP. The same is also true for tiles. If they aren’t converted to bitmaps, small white lines may also show up between the tiles.
• EPS in EPS: Avoid EPS-nesting: never put an EPS-drawing in another EPS-drawing. Use “copy” and “paste” from one drawing to the other to create only one file.
• Size: If the drawing contains bitmap images (scans,..) you should never enlarge or reduce the drawing more than 20 percent in your layout application. Enlarging it will lead to pixelization and staircasing. Reducing it too much will lead to a loss in sharpness and contrast.

Communication with your trade shop or printer

• Platform issues: Select a printer that uses the same platform as you do. Converting documents from Mac to PC or vice versa can be done but leads to problems with fonts and is prone to errors.
• Output form: Most companies have a form that has to be filled in for every job. Please do this properly.
• Hard-copy: Always provide your trade shop or printer with a to-size printout of your document. That way the prepress operator knows what he can expect from your file. Mark last-minute changes clearly on this proof if there is no time for updated printouts.
• File format: There are a number of ways in which you can exchange your document with the service bureau:
  1. As a native file: just send your QuarkXPress, InDesign or whatever file and don’t forget to include all images and fonts.
  2. As a PostScript file. In this case, you are responsible for the creation of the PostScript data as well as their content. The service bureau cannot easily fix any mistakes you made.
  3. As a PDF file. This is more practical than the use of PostScript but you have to be aware of the proper procedure to create PDF files. The GWGsite offers great advice on delivering proper print-ready files from a number of applications.
  4. Using another format like TIFF/IT P1, CT/LW,…

• File inclusion: If you supply native InDesign,… files to the printer, you should include all the files with your job. Don’t forget any fonts or images. Provide all fonts: maybe your service bureau has the font but it is a different type or from a different manufacturer. This can lead to text rewraps. Include instructions when you have made custom modifications to fonts. There are several pre-flight applications available on the market to make sure you provide a failure proof document. Use them.
• Garbage: Do not include superfluous material. If the folder you want to send still contains some old files that you no longer need, delete them!
• A copy of files: Never give a printer or trade shop the only copy of your files.
• Responsibility: Never assume that anyone will do more than they are paid for. If there are typos in your files, a printer will leave them untouched unless you agreed to pay for proof-reading. The same applies for removing color casts or other corrections in the images.
• FTP: compress files before sending them to a FTP-site. Incorrect FTP-settings or cross-platform issues may damage uncompressed files. ZIP and Stuffit are compression systems that everyone supports.
• Label disks: Always label CDs or DVDs with your name and contact information. If it is a set of disks, number them (e.g. 1 of 4, 2 of 4,..)