Dots per inch (DPI) is a measure of printer resolution, although it is commonly applied, somewhat inappropriately, to monitors, scanners, and even digital cameras.
In the case of monitors, DPI refers to the number of pixels present per inch of screen.
For printers, the DPI specification indicates the number of dots in each inch that the printer is able to achieve to form text or graphics on the printed page. The higher this specification, the finer the text or image. To save ink, a lower concentration is often used for drafts or routine paperwork. This setting can be 300 or even 150 DPI. High resolution starts at 600 for standard printers and can greatly exceed for color printers designed to produce digital photography or other high resolution images.
DPI is commonly applied to digital cameras.
In the case of monitors, DPI refers to the number of pixels present per inch of screen. The technically correct term is “PPI” or pixels per inch, but DPI is commonly used instead. A 1280 x 1024 display setting has 1.3 million pixels on the screen, while an 800 x 600 setting has 480,000, or less than half the resolution of the highest setting. With fewer pixels, the image will not have the clarity that can be achieved with higher saturation. Each dot or pixel reflects a certain color and brightness. The higher the number of pixels, the more detailed the image can be. More pixels also require more memory, and it may take longer to “paint” images, depending on the system’s graphics card, processor, and other components.
Scanners also operate at different resolutions. Scanning time will increase with higher DPI settings as the scanner must collect and store more data. However, the higher the requested resolution, the richer the resulting image. A high resolution or DPI setting mimics the original image more truthfully than lower DPI settings are capable of. If the image is enlarged, a high setting is required. Otherwise, the enlarged image will be “blocky” or blurry because the software has no information to fill in the extra space when the image is enlarged. Instead, it “blasts” each pixel to “blur” it into a wider area.
Digital cameras have their own specifications in terms of megapixels and resolution, but DPI is often mentioned in this context. As in all cases with regard to the output image, a digital camera with today’s most basic resolution standards – 3.0 megapixels and better – will produce an image capable of taking advantage of a very high DPI setting on the printer. However, if your printer is only capable of 600 DPI, the extra camera resolution will be lost in the printing process. When purchasing or upgrading components, it is critical that each product is able to support the highest standards of any interface product.