Prepress > Design Considerations
About artwork and photos
- Save all full-color artwork and photograph files as CMYK.
- Color images files should be 300 DPI and black and white halftone files should be at 1200 DPI, and not more than +15% or -15% of the reproduction size.
- Artwork downloaded from a web site is usually too low-resolution for print reproduction.
- Lineart should be scanned at 1200 DPI, not more than +15% or -15% of the reproduction size, and then saved as TIFF files.
- Avoid using lines within artwork that are thinner than .5 point.
Using black ink solids
- In order to guarantee that the image files will be big enough, please scan them at the size they will be reproduced, and at a resolution of 1200 DPI.
- Use descreen when you are scanning an image that already contains a halftone screen.
- Retouch photos as needed.
- Crop image based on design. Please note that the final image setting should be as close as possible to 1200 DPI.
- Adjust tonal levels as needed. Images on screen should look slightly lighter than expected.
- Save grayscale images as TIFF files.
If a large area of solid black will be crossing other built tints, there will be a difference in density between the areas over color and those that are not over color. The solution is to build a "rich black" tint mix as follows:
Using this rich black will avoid any obvious density variations in black solids. It is also a good formula for producing a dense, uniform black solid, even when it will not be crossing other colors.
Other black elements such as rules, type, and thin illustration elements should be made up of 100% black and set to overprint.
Some notes about trapping
Generally process colors do not need to be trapped, although there are some exceptions. Process tint mixes, being made up of only the four process inks, usually already share common inks. For example, when the 20% cyan in one tint mix is butted up against the 40% cyan in a neighboring tint mix, no white paper will show through if registration is slightly off. The exception to this general rule is when your process mixes do not have common inks. An orange made up entirely of magenta and yellow next to a blue composed only of cyan and black will need to be trapped.
- If you submit PDF files, please note that you have to set up trapping before submitting your PDFs since we cannot adjust PDF files.
- An object such as a rule or small type can be too thin to trap. Essentially the trap itself would "eat away" the entire thickness of the object. In this situation consider overprinting the object, but remember that overprinting will add the assigned color of the object to the underlying color and may affect the object color.
- In Quark XPress: use an amount of 0.15 in the trapping preferences for the object you are trapping. Turn "Process Trap" off.
- In Adobe Illustrator trapping is not an application-wide setting, but is controlled by the line weights you assign to individual objects. Please note that you will need to assign a line thickness that is twice the size of the trap you desire because these programs measure line weights from the center out. For a trap of 0.15 points, assign a stroke of 0.3 point and set it to overprint. Set the object fill color to not overprint. If you create a trapped image in Illustrator and then import it into Quark, any reduction or enlargement of the imported image will reduce or enlarge the trap as well.