File format is very critical in the printing industry.
Bitmap formats do not work well for such processes as Quality Printing of Logos, Sign Making, and T-Shirt Printing. Bitmap formats are best suited for photographs but must be at a high enough resolution as to supply the output device with enough pixels to create a clear image at the lpi (lines per inch) at which they will be printed. In most cases for high quality printing it will be around 300 dpi.
NOTE: LPI and DPI are NOT the same thing. LPI is the lines per inch (in printing terms) in the photo when printed, DPI refers to the output divise (printer or imagesetter) the files are printed on. Most printing output is done on divises with 1200 to 3400 dpi.
Whenever you type text, it is in vector format.
If you convert vector to bitmap as in any photo type software (Photoshop, PrintShop, PrintMaster etc.), it CANNOT be converted back.
Some applications use both vector and bitmap, ie: Quark XPress, PageMaker, Microsoft Publisher, CorelDRAW, Adobe Illustrator and several others. Please check with us before you develop the layout for advise on the best application to use.
Some applications convert vector to bitmap and set the graphics to a resolution suitable for your default printer only. This makes it very difficult to produce a quality product. Word processor applications are almost all this type.
In order to print photos on a printing press they must be set to CMYK (CYAN, MAGENTA, YELLOW AND BLACK. The 4 colors used in printing). If they are left in RGB (RED, GREEN, BLUE), which most scanned photos are, they will print in black and white only.
Color output devices such as color printers usually print photos best when the photos as in RGB. When sending photos for us to create the layout, leave them in RGB.
Always supply us with the layout as created in the original format.
File Format vs File Extension:
The term vector or bitmap is the format of a file. The extension merely indicates the software it is saved from with some cross referencing to format ie. jpg is a generic format which can be opened by several software packages and always indicates a bitmap grayscale or color format.
The PC world uses file extensions on all files saved to disk. Macintosh (used in most graphic layout work) does not. The extension is inside the actual file and is called up when you double click on the file or try to open it with a particular software.
DPI (dots per inch) has nothing to do with the file type (or software saved from). If you are scanning an art piece, you need to set your scanner to the dpi you desire. If the art is lineart (no shades as in a photograph) you should set your scanner to lineart and scan at 800 dpi. What that means is the scanner only picks up a black or white dot. Thus the file is small in size and the edges of the lines are much finer than in a 300 dpi or 72 dpi scan. If the art is a photograph you should set your scanner to grayscale or color and scan at 300 dpi. What that means is the scanner picks up shades of color or gray (whichever the case may be). This is done by interpolating the shades the scanner sees into bit depth. ie. 8, 24 or 32. Then when we print to an imagesetter (high end laser) the imagesetter interpolates the bitdepth into lpi (lines per inch). Imagesetters do this on a mathematical scale. The rule is 1/8th of the dpi capability of the imagesetter. ie. An imagesetter with a dpi capability of 2400 dpi can produce a photo at 300 lpi and a lineart piece at the full 2400 dpi. Vector art, because of the type of file, is imaged at fill dpi resolution (2400) in which the dots along the edges canNOT be distinguished. Bitmap art that is only black and white dots can be imaged at the resolution it is scanned at. That's why we recommend at least 800 dpi. Therefore, if we start with a file that is 72 dpi in resolution and in bitmap grayscale or color format, we end up with an image that has very course dots along the edges. Even if the image is a photograph it is only 25% as sharp as it needs to be.
The file type the art is saved in really doesn't matter as long as the file type does not change the art from vector to bitmap. We use Adobe Illustrator or CorelDraw files as they maintain the vector format. We use Adobe Photoshop for all photo work. We us .jpg a lot for photographs because it compresses the file to a smaller size which is nice when sending over the internet. But if the photo is to be printed in full color, .jpg looses some of the color information so we try to avoid that format for high end printing.