Image Resolution 2 – DPI & Photo Size
In our previous blog we had a look at megapixels (MP) and what the term actually means. If you missed it or want to refresh your memory of it you can find it by clicking Image Resolution What are Megapixels
In this blog we’re going to take a look at the relationship between megapixels and printing a photo.
If we think of:
Megapixels as the basic building block of a digital image
‘dots’ are the basic building blocks of printing.
I can’t help but wonder when we’re going to upgrade ‘dots’ to something much more digital-speak like ‘megaparticles’ or ‘agglomoration-iotas’, however in the meantime we’re going to have to stick with plain old boring ‘dots’….
What is DPI?
So plain old boring dots… coupled together with equally plain old boring printing…. coupled with the distinctly non-digitial-speak metric ‘inch’… and you get ‘dots per inch’ or DPI.
This is simply the number of dots contained in one square inch, the higher the number the clearer the image. A newspaper is printed at 72DPI and a glossy magazine printed at 360DPI. The human eye can’t really make out much more detail than 360DPI so that tends to be the highest used for printing.
As previously discussed an 8MP camera will have a sensor that picks up 3,264 X 2,448 pixels (typically). A 10″ X 8″ print at 300DPI will have 3,000 X 2,400 dots. So the relationship between the pixels and the image is:
Horizontal Pixels – 3,264
Horizontal Dots – 3,000
Vertical Pixels – 2,448
Vertical Dots – 2,400
Sweet! A 10″ X 8″ print at 300DPI with a few pixels to spare – a perfect photo with a pretty close match of pixels to dots printed!
What if a customer comes into us with a digital photo taken with a 8MP camera and asks us to print a 16″ X 12″ photo, will we be reduced to gnashing of teeth and perhaps crying at the foolishness of humanity? Not at all.
The reality is that you can print at lower resolutions and still get fantastic results. Most of us don’t shove our nose up against the 20″ x 30″ print taking pride of place on a friends wall and examine it in minute detail. The closest examination it will get is from a few feet – so it’s not the end of the world if your megapixels and DPI are not in a perfect zen-like balance.
Whether the vast majority of people looking at a photo printed at 360DPI versus one at 200DPI will see a noticeable difference is debatable. However – it is worth remembering there is an important relationship between megapixels and print size, even if it’s not the deciding factor in the end quality of your print.
Our Contact Details
The Pictorium Ltd
No 3 Monkstown Court
Monkstown Farm – Opposite The Credit Union
Monkstown, Co. Dublin
Tel: +353 1 284 6106
Our Opening Hours
Mon-Fri: 9.30am to 5.30pm
Saturday: 10am to 4pm