Thursday, April 25, 2013

How you can Scan Photos - The Very Best DPI Setting to Scan Pictures With Whenever You Simply want to Get It Done Once

Having your entire family photo collection digitized on your computer is a wonderful thing. From all your hard work, not only can you pass them around through email and social networking sites, you can make beautiful coffee table photo books, holiday cards and calendars. But please don't rush into this project without doing some homework first. You certainly don't want to find out when you're done that you scanned them incorrectly because you used the wrong DPI setting. You want to scan each photo just one time and be done with it -- right?

A Little Background

When I started to scan my collection, I did a lot of research and then committed myself to a lot of trial and error on my own photos before I came to a set of dpi (dots per inch) settings that I knew would produce beneficial "archival-worthy" digital images. Which seriously is what we all should be shooting for -- scans that are so good, of such high resolution and quality, that they can be used for almost anything we need them for in the years to come. Sure you can scan an image really quickly so you can throw it up on a social networking site, but why not do it the right way so it can be archival quality and treasured forever.

For those wondering, the dpi setting is just a simple pull-down menu in your scanning software. It typically has a range anywhere from 50 dpi all the way up to 6400 dpi or more. It's one of the first things you have to set after placing your paper print in the scanner bed. And if you really want to know what it does, dpi is the critical variable in a fairly simple mathematical equation that will determine the following in your new scanned image -- the amount of detail it will contain, how much resolution (pixels) it will be made up of, and how large the file size will be. And what's bad is that it's so easy to pick either too low of a number to save time waiting for the scanner to work its magic, or too high of a number thinking "bigger is always better."

In order to figure out what dpi settings will work for our large collections with lots of different sized photos, I tried to summarize all of my concerns into a question and then went out to solve it:
"What dpi should we scan our paper photographs with that will capture as much detail stored in them as we possibly can, will create a manageable file size, but will also produce enough image resolution should we choose to do some radical cropping or print out an average-sized enlargement from them someday?"

Figuring Out the Best DPI to Scan Paper Photographs

If you do research on the internet with your favorite search engine, almost all of those willing to share their expertise will tell you 300 dpi is the optimal setting for paper prints. I certainly wouldn't disagree that this number has its advantages. A photograph that was developed and printed on paper through the decades that make up most of our collections, only has between 200 to 300 dpi worth of detail in it. They simply don't possess as much information in them as the original negative they were made from.

So scanning at 300 dpi will almost guarantee that you capture as much detail as you possibly can. And a 300 dpi scan doesn't take very long to complete a pass. My Epson Perfection v600 only took 12 seconds to scan a 3.5 x 3.5" photograph -- only 1 second longer than had I scanned it at 200 dpi.

There is actually less harm in scanning at too high of a dpi than there is too low of one. However, you never want to scan at a dpi that is higher than the highest "optical resolution" that your scanner will scan with. My scanner says on the outside of the box (and in the manual) it is rated for 6400 x 9600 dpi. The first number tells me I should never scan higher than 6400 dpi or the scanner's software will resort to digitally "zooming in" to my photo and will create a less than perfect representation.

Even though these higher settings like 2000 dpi or more are really intended to scan really small objects full of detail like slides and other film negatives, in most cases it won't hurt the quality of your image to use them on prints. The scan itself however will take a lot longer and the file size could be rather large. I did a test and my 3.5 x 3.5" photograph scanned at 4800 dpi (48-bit) took 6 minutes and 37 seconds to complete and was a whopping 2.22 GB!

The sweet spot for dpi -- not too low and not too high -- is the one that won't produce huge unmanageable file sizes, will give you all the detail from your original paper prints, but will also give you enough detail so you can print out a decent 8x10 enlargement someday without resorting to difficult and secret Photoshop techniques.

So here's what you've been waiting for. Here's what I found to be the best dpi settings to use.

The Best DPI Settings to Archive Your Paper Prints
2.5 x 3.5 " - 1000 dpi 3.5 x 3.5 " - 900 dpi 4 x 4.5" - 600 dpi 3.5 x 5" - 600 dpi 4 x 5" - 600 dpi 4 x 6" - 600 dpi 4 x 7" - 600 dpi 5 x 7" - 600 dpi 8 x 10" - 600 dpi

So this has been a quick and simplified explanation. If you would like to check out the complete story, with pictures, colorful charts and all of the details, find out how to scan with "The DPI You Should Be Scanning Your Paper Photographs."

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