Hi Res vs Low Res: Why You Should Care
Perhaps you have heard the terms “hi res” and “low res” when talking about digital photos. But what exactly does hi res and low res mean, and why should you care?
The term resolution (res for short) is used in both the digital and print world.
Image resolution is the detail an image holds. Low resolution images (aka low res) will have less information – meaning fewer pixels (if digital) or dots (if print) per square inch.
High res images will have much more information. Pixels per inch (PPI) or dots per inch (DPI) measure how sharp an image is.
A colleague shared this helpful definition recently: the term DPI (dots per inch) is only for printing. Any time you scan something (photo, transparency, document, artwork etc) you’re converting something with physical dimensions to pixels, so PPI (pixels per inch) is the correct technical term.
You’ve seen low-res digital images. They are pixelated to a certain degree, sometimes appearing as a compilation of boxes or squares pieced together (as per our example).
Online and web graphics, which are usually low res (72 PPI), look fine on a computer screen at their display size. But printing them would result in a pixelated appearance – something to avoid.
A high resolution image of 300 PPI @ a one-to-one dimension (the industry standard for printing) would be a much better choice.
What are low res files good for?
As I’ve mentioned above, low res files are fine for screens – on social media, websites and smaller digital frames. If you text or receive photos via apps like Instagram and What’s App, those are low res files.
And many online photo sites like Shutterfly compress any hi res files that are uploaded to their site, so if you try to retrieve them you’ll typically get back low res files. Which is not ideal, especially if those are your only copies (and if you are a user of Shutterfly Share Sites, please be aware that Shutterfly will be discontinuing the Share Sites service in March 2023).
What are hi res files good for?
When taking photographs (via a smartphone or DSLR), an effective resolution starts around 300 PPI and goes up from there. All smart phones will automatically create hi res files of your photos.
As a result, these photos look great printed or as framed images. Hi res files can also be enlarged to a degree and cropped without losing much detail. This is important if you are creating printed products such as photo books. Low res images can be used, but need to be small – usually matchbox size – to be easily viewable.
Most photo collections have a combination of low res and hi res files. When culling duplicate digital photos, it’s always best to delete the lower resolution versions of images.
When we digitize print materials, we use a process called camera scanning that results in higher resolution, archival-quality scans. These hi res files are perfect for print reproduction.
35mm slides and negatives, being much smaller originals, are output at a high PPI (2400) so the digital versions are clear and viewable at roughly 8 times the size of a slide.
Prints smaller than 8×10” are scanned at 600 PPI which gives the option for enlarging up to 200% when printing. For example, a 3×5” photo scanned at 600 PPI can be printed at 6×10”. These higher resolution files are ideal for long-term preservation as well.