Always create files at 300 DPI resolution if you intend to print them. Make sure to remember that resizing an existing image to 300 DPI is not an option as it will only duplicate existing pixels and give you a blurry image — you have to create artwork with enough pixels from the very beginning.
If you want to check at which size your existing photos and other artwork can print well, simply divide their pixel dimensions by 300. For example, a 1280 x 1024 pixel photo will print well at 4.26 x 3.42 inches — anything larger than that will make it blurry
Note: you don’t have to worry about DPI for vector objects created in Illustrator or CorelDRAW — they print well at any size. The DPI relates only to bitmap images traditionally handled by Photoshop.
DPI
DPI is not really used to describe the resolution number of dots per inch in a digital print and the printing resolution of a hard copy print dot gain; the increase in the size of the halftone dots during printing. This is caused by the spreading of ink on the surface of the media.
DPI
DPI is not really used to describe the resolution number of dots per inch in a digital print and the printing resolution of a hard copy print dot gain; the increase in the size of the halftone dots during printing. This is caused by the spreading of ink on the surface of the media.
Up to a point, printers with higher DPI produce clearer and more detailed output. A printer does not necessarily have a single DPI measurement; it is dependent on print mode, which is usually influenced by driver settings. The range of DPI supported by a printer is most dependent on the print head technology it uses. A dot matrix printer, for example, applies ink via tiny rods striking an ink ribbon, and has a relatively low resolution, typically in the range of 60 to 90 DPI. An inkjet printer sprays ink through tiny nozzles, and is typically capable of 300-600 DPI. A laser printer applies toner through a controlled electrostatic charge, and may be in the range of 600 to 1,800 DPI.
PPI
Pixels per inch (PPI) or pixel density is a measurement of the resolution of devices in various contexts: typically computer displays, image scanners, and digital camera image sensors. PI can also describe the resolution, in pixels, of an image to be printed within a specified space. Note, the unit is not square inches. For instance, a 100×100 pixel image that is printed in a 1-inch square has a resolution of 100 pixels per inch (PPI). Used in this way, the measurement is meaningful when printing an image.
Good quality photographs usually require 300 pixels per inch, at 100% size, when printed onto coated paper stock, using a printing screen of 150 lines per inch (lpi). This delivers a quality factor of 2, which delivers optimum quality. The lowest acceptable quality factor is considered to be 1.5, which equates to printing a 175ppi image using a 150 lpi screen onto coated paper. Screen frequency is determined by the type of paper that the image is to be printed on. An absorbent paper surface, uncoated recycled paper for instance, will allow the droplets of ink to spread (dot gain), and so requires a more open printing screen.
Good quality photographs usually require 300 pixels per inch, at 100% size, when printed onto coated paper stock, using a printing screen of 150 lines per inch (lpi). This delivers a quality factor of 2, which delivers optimum quality. The lowest acceptable quality factor is considered to be 1.5, which equates to printing a 175ppi image using a 150 lpi screen onto coated paper. Screen frequency is determined by the type of paper that the image is to be printed on. An absorbent paper surface, uncoated recycled paper for instance, will allow the droplets of ink to spread (dot gain), and so requires a more open printing screen.
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