One of the most important decisions you face when scanning anything with your scanner is choosing what dpi (“dots per inch”) to scan with.
And specifically for this post, what is the best DPI to use when scanning and archiving your 8×10″ and smaller paper photographic prints — which for most people, make up the majority of our pre-digital collection.
Making this decision was very challenging for me and certainly a huge part of my 8-year delay. The reason for this is that dpi (sometimes also interchangeably referred to as ppi for “pixels per inch”) is the critical variable in determining several important outcomes for your scanned digital images:
- Detail – how much image detail you will extract from your photograph
- Image Size – how much resolution in pixels you will have to work with (e.g. 2400 x 3000 pixels)
- File Size – how large the file size will become (e.g. 64.9 MB or 64,878,462 bytes)
It's definitely a decision you want to make before you complete your very first scan. Trust me, you don't want to get halfway through your collection and realize you scanned too high, and your computer is running sluggishly and your image quality looks weird — soft and pixelated. Or worse, you find out you could have been extracting more image detail from your prints if you had just chosen a slightly higher dpi, to begin with.
Finding a Manageable Scanning DPI Game Plan
When trying to decide which dpi to scan and archive your photos with, the “big picture” that you want to keep in mind is the following:
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, print them out to an average-sized enlargement on photo paper, or display them on high-definition monitors and televisions.
If you study the routine of a professional photo restorer, you will learn they tend to see each photograph as a separate unique challenge — like a doctor attending to an ailing patient for the first time.
It's a laborious investigative process for them. They may even scan each print several times with varying dpi's, carefully comparing each image until they find the most appropriate dpi for the photo's personalized workflow.
Because you probably have anywhere from hundreds to thousands of photos in your family's collection, it's not practical or even reasonable for me to suggest we would ever want to attempt such perfectionism. So, to make things manageable, I wanted to come up with scanning dpi values that we could all use that would be easy for all of us.
The Best Scanning DPI for Your Paper Prints
Most everything you will need to know to decide which DPI to scan your photos with, including my recommended dpi value(s) you should use, is discussed in the special video right below here.
The video is a section taken from one of my lessons on scanner settings in my video training course on scanning and organizing photos. Until now you needed to be a Member, but for a limited time, I've made this particular section on “The Best Scanning DPI for Paper Prints” available for those who are free subscribers to my email list too.
Think of this as a Mini-Lesson on learning the best way to set your scanner DPI setting for your photo collections!
Start Here With This Mini-Lesson
And here are some other important points that aren't mentioned in the video above that will also help you understand how your scanner works and how the dpi selection will affect your family's photo collection.
Problems When Choosing a DPI Based on the Time Required to Scan
One of the biggest mistakes I find people make when choosing the dpi is allowing the length of time it takes to complete the scan influence their decision. Those new to scanning may be surprised to learn that the higher the dpi, the longer it takes for the scanner to make its capturing pass and for the computer to process the information. I've recorded for you the time it takes the Epson Perfection v600 flatbed scanner to complete scans with various dpi's set.
Scanning Times for a 3.5×3.5″ Print on an Epson Perfection V600
|Time Elapsed (mins:sec)||:11||:12||:14||:18||:31||1:02||2:34||3:53||6:37|
You can see there is, in fact, a vast difference in the amount of time required to scan at one of its lowest settings (150 dpi) and scanning with one of its highest (4800 dpi). But more importantly, I want you to notice the time it takes to scan between the range of 300 dpi through 800 dpi. It's relatively almost the same length of time. With this model, we are only talking about a difference of 19 seconds. And specifically between 300 and 600 dpi, it's only a measly 6 seconds.
All scanners scan at different speeds so your scanner may or may not be slower than this model. But if it is, chances are the percentage of time between each of the dpi settings will be very similar. Regardless, if you think you are going to be one of the ones waiting impatiently for your scanner to work its magic on a higher dpi, I would like you to remember this. Scanning and archiving your family's photo collection is an investment. It's going to be an investment of your time and energy, and for that reason, more than likely, you will only want to do this project one time.
I believe it's worth a few extra moments to ensure your image quality isn't being compromised by rushing the process. Open wounds need time to heal, baking dough needs time to rise, and photo scanners need time to scan. See where I'm going here?
To fill the extra time, consider taking an extra-long sip of your nonfat mocha latte, play solitaire, have a television on next to your scanner, or better yet – lightly dust off your next photo to be scanned with a lint-free cloth!
Are You Looking for the Fastest Flatbed Scanners?
Optical Resolutions vs. Digital
The really high resolutions, however — 2400, 3200, and 4800 dpi — are really intended for capturing really small and highly detailed sources like film negatives and slides.
If you want to experiment with these resolutions, just make sure you stay away from the “digital” ones. On the box your scanner or printer/scanner combo came in, you will see a rating with two numbers. The Epson Perfection v600, for example, is rated for 6400 x 9600 dpi of resolution. The first number is the highest “optical” resolution your scanner is capable of, and therefore the highest dpi you should ever scan with. The second number is often the highest resolution it's capable of scanning digitally — faking the results by interpolating the data. Thankfully, some scanning software now won't even let you select the digital dpi's from the list.
In the case of the Epson Perfection v600, the maximum “digital” resolution is actually 12,800 dpi, much higher than the second number given. So you may need to consult your specifications printed on the box or find them in the printed or .pdf manual if you are curious about your scanner's digital capabilities.
The Advantage of Having All of This Archived Image Resolution
In the end, there won't be any benefit to having our entire collection in a digital format if we aren't able to make paper prints from them like we can with our film negatives. Just like we need a certain amount of “dpi” to capture images into the computer, we need a certain amount to print them back out to paper. The larger the piece of paper you want to print on, the more image resolution you are going to need in your digital files.
Printers today need on average between 200 and 300 ppi (dpi) of image resolution information to print a high-quality image on high-quality paper. And I am going to make the assumption that most of us seldom print out a photograph larger than 8×10 inches. This is good because almost all of the printers out there won't even print larger than 8×10 inches!
I know you probably hate math as much as the next person, so don't worry – I'll do it for you. What this means is that in order to print out a photo on an 8×10″ piece of paper, we need up to a 2400 x 3000 ppi (dpi) image. Here's my work:
(8 inches x 300 ppi) x (10 inches x 300 ppi) = 2400 pixels x 3000 pixels
Given a choice, without a doubt in my mind, it's better to scan too high than to scan too low.
And if you don't want to take just my word for it (grin), when I started learning all about scanning years ago, I found great comfort in this quote from Wayne Fulton of scantips.com and kept going back to it:
It is true that if the image might be resized after the scan, it's always much better quality to resize to reduce the image size rather than to resize to increase the image size. If you aren't sure what your future intentions for the image might be, and won't be able to scan it again, then it's probably best to err on the large side (if storage space allows, up to reasonable amounts anyway). Resizing to be smaller discards excess pixels. But resizing to be larger must create (or fake) new interpolated pixels which were not in the original scan. There is no additional detail possible in interpolated pixels, even if the image is larger. The results are not at all the same as scanning at the higher resolution.
Alright, again, if you haven't watched the special video above, I would highly recommend you watch it. Most of the information you need to know is in this easy-to-follow mini-lesson.
After watching the video and reading this article, has this made you change your mind one way or the other? Tell me what you think about all of this in the comment section below. I'd love to hear your thoughts.