True DPI ratings vs. interpolated DPI ratings

 

What is DPI?

DPI or dots per inch is a measure of the resolution of a scan or print. In other words, it is a measure of a scanner or printer's accuracy based upon how many individual dots can be read, or printed within a one square inch area. There are two main ways that DPI is used in the industry, and the difference between them can be very important. There are other considerations that weigh into a machine's DPI capabilities such as scan/print speed, and other various driver settings. Optical DPI – Optical, or actual DPI is a measurement of how many dots per inch a scanner/printer is capable of handling without digitally changing the scan and or print.

 

Optical DPI:

Optical DPIis generally considered to be the most accurate measurement of a scanner or printer's capabilities. Most large format scanners and printers will have a DPI range from 96 up to 600 DPI. Interpolated DPI – Interpolated DPI is a measurement that refers to images that has been re-sized. When an image that is 600 optical DPI is blown up, the DPI needs to be interpolated by software in order for the image to retain integrity. This means that the software will expand the image, and then go through the image and fill in the white space that is created between the dots when the image is expanded. Interpolated images, while a good concept in principle, lack the accuracy and definition of non interpolated images. Interpolated DPI is often what manufacturers list as the product's DPI in order to make the product appear more capable than it really is. If you are unsure as to which DPI information you are looking at for a specific machine, then give us a call so that we can help you accurately assess the machine's capabilities.

 

DPI and Scanning Speed:

Scanners usually list the speed capabilities of the machine in their sales materials. Generally, scans that are conducted at higher speeds will see a reduction in resolution quality. However, this does not mean that using the slowest setting will necessarily give you the best possible result. Most scanners will have an optimal threshold that will produce quality scans. We are happy to make recommendations as to optimal operational parameters based upon the scanner, scanning technology, and documents being scanned. Generally, the best way to determine the proper settings for your scanning needs is through trial and error.

 

Tips for Scanning and Printing for Optimal DPI scanning and plotting:

 

Avoid interpolating the DPI.

Scan at a lower speed When scanning.

Bring your white and black points in a little.