The Basics: DPI (Dots Per Inch)

DPI (Dots Per Inch) in digital imaging means how many pixels per square inch make up the image. For example, if I scan a 1 inch by 1 inch piece of paper in 300 DPI, then there are 300 pixels in the image that I scanned. If I looked at the digital image and realized that it did not show enough detail of the image, then I would scan it at 600 DPI. Now, the digital image has 600 pixels that represent the image. You can keep going up and up, but there reaches a point where adding more pixels does not gain you any more detail. Why? Because at some point you start picking up detail about the paper (or medium) that the items is on. You start to see the fibers in a piece of paper, or the dimples on it’s surface. Once you start picking up that level of detail, you are actually creating more “noise” in the image than is necessary and you need to back off on the DPI.

Most printed text, for example, is printed in 80-90 DPI on a page. However, this does not mean you can scan the image at 80-90 DPI, because your dots and the dots on the page might not match up. You will want to raise the DPI of the scan 2 to 3 times (say 200-300 DPI) to get a decent image of the printed text.

For micro-text (like on Microfiche, microfilm, or micro-opaque cards), this gets much more complicated. For micro-opaque cards, for example, you may need to scan them at 1200 DPI to get a clear image. This is because the text is so small.

Comments

Documentation and Good Management in Digital Libraries

This month is all about self-evaluations for me and my employees. Because of this, I have been thinking about how a manager is supposed to show their work and their worth. The easy answer is to say that if the employees are doing well, then the supervisor is good. It could be that the employees are doing well despite a bad supervisor. An employee doing badly is also not a sign of a bad supervisor. So what tangible thing can I say makes me a good or bad supervisor? Throughout the year, I try to focus on the actions I take to make my employees' lives at work better. I try to give them direction, advice, and help make things easier. I also try to champion them. Things do not always work but I adjust. When I sit down to write my own evaluation, though, I end up writing about documentation. To me, that is a concrete indicator of a good supervisor. They care enough about the work, and their employees, to write things down and make a record. I want to challenge everyone to write

Bureau of Indian Affairs- Digital Collection

The Bureau of Indian Affairs is one of the oldest Bureaus in the United States. It was established in 1824 by Secretary of War John C. Calhoun . While the history of the organization has been controversial, their records are open to the public. This collection brings together letters distributed from the Bureau of Indian Affairs starting in 1832 and going on into 1966. View the rest of the collection: http://bit.ly/2h0hKvW

The Workload Iceberg for Digital Collections and Initiatives

In the last few weeks, I was asked to write a small paragraph explaining my area to others in the library. I was happy to do this, as many people say they don’t know what my people do. It’s sometimes hard to explain to others what we do without going into overtly technical topics and terms. If we have done our job right, we’re practically invisible, which is the way it should be. Anyway, writing the description made me realize why there is often a mis-match between what we do and what people think we do. I’ll let you read the description yourself. I’ve underlined the important bit. “Digital Resources is primarily an Open Access publisher. We publish both born digital items (produced by students or faculty), and we scan to publish or republish old items. We curate digital collections through the whole digital life-cycle. Our work is a bit different from other departments because the more work we finish; the more work we create in having to maintain the collections. We’re no

The Digital Dungeon

Search This Blog