Prepress
- What is dpi? What is lpi? What should I scan/set my files at?
Dpi stands for dots per inch, and when displayed on screen this is also often referred to as ppi (pixels per inch). On screen, what would be printed as dots is displayed using pixels because there are no "dots" on monitors. When printing however, images are printed using dots (if you look closely at virtually any printed piece you can see them). Dpi measures the overall resolution of an image in reference to these dots.
Lpi stands for lines per inch, which corresponds to the number of lines per inch in a halftone screen. This concept is slightly more subtle than the concept of dpi, because it also involves dots, but dots that are often referred to as "machine" dots (and there happens to be a nice correlation between lpi and dpi to guide what to set your files at). To understand lpi, it is necessary to see that a printing press can only print solid color, so to get percentages of color, the solid color is screened, or rather, very small solid dots are put on the paper to simulate tones. Lpi measures how many lines, that make up these screens, are in one inch, and is a measure of resolution with respect to offset printing.
The primary thing to remember is that dpi is something that you should set when creating your files in a non-vector format but lpi, except in very rare cases, should not be set or locked into your files, it will be automatically set by our RIPs (the thing that interprets your file and allows us to proof and plate it).
The correlation between dpi and lpi that was mentioned earlier, is that the rule of thumb is to make images approximately twice that of the linescreen. Brenner Printing prints all sheetfed books at approximately 175 lpi and newsprint books at 150 lpi, meaning that images should be created at 350 and 300 dpi respectively. However, this is just a rule of thumb, and most people will find that 300 dpi shows no degradation from 350 dpi and saves them space.
One other exception to especially note is: although type should not be embedded inside non-vector graphics when this is unavoidable, the dpi should be set at or above 600 dpi.
And finally, lineart should be set at 1200 dpi.
So once again:- Don't set or lock in lpi (rare exceptions: if you don't already know the exceptions, you should abide by this rule)
- 300-350 dpi for grayscale and process pictures (at size)
- 600+ dpi if placing type in bitmap graphics
- 1200 dpi for lineart
- How can I get my files to you?
There are three main methods:- Media (Zip, CD, DVD, etc) - Please see Digital Prepress page
- FTP - For information, please see FTP under hints
- Email - For information, please see Email under hints
Incidentally, the first tends to be the fastest given the size of the files that make up entire projects, and continues to be the recommended method.
- What kind of files/programs do you accept/recommend?
As far as accepting, check the Digital Prepress page. We recommend Adobe products (PageMaker, Illustrator, PhotoShop, InDesign), but acceptable substitutes for these recommendations would be QuarkXPress for PageMaker or InDesign and Freehand for Illustrator. PhotoShop literally has no substitute, it is the de facto standard for image manipulation. If you are planning on using these programs, it would be advisable to read the manual (compared to most programs, these manuals are invaluable and actually readable). All of the above are very powerful programs, and understanding their features will make the whole process much smoother.
- Will you accept a RGB File? We prefer that files sent to us are CMYK. As there can be significant color shifting while converting an RGB to CMYK, we feel it best if the client make that conversion.
- How can I check my job before it is printed to make sure everything is alright?
You can get a proof, in fact, we encourage it. See the Digital Prepress page for details on our proofing process.
- Are you a CtP (Computer-to-Plate) shop?
Most definitely. While we still maintain the capability to make plates from film, we no longer make film. Going to CtP increases our productivity, lowers total cost, and allows us to produce perfectly registered crisp printing.
- Any more tips?
Check out the hints section.
- I have more/specific questions.!?
Call us. A representative from the digital prepress department will be happy to speak to you about your project.