How Much Resolution Do You Need?

If you’re a photographer, the internet has been polluted with people eager to spend money on either the new D800 or 5D. Both are reasonable upgrades but for the most part, Nikon and Canon has a similar fan base to Apple in which everyone complains what’s missing, but they’ll still line up to buy it. But that’s beside the point.

The D800 comes with a resolution of 38 million pixels and while there are for sure people that can use and need every bit of that, those people are not the average user. I don’t even think Canon makes an slr under 18 MP now. Marketing tells us bigger is better.

I’ll go on record by saying that I want as much resolution as I can possibly get. You never know when an agency will call and in the stock world, pricing is determined by use and size. But regardless of what the market desires, how much is actually necessary for most use cases?

Star Trails over PEI National Park

Today’s Image – Covehead Lighthouse

Here is an image that I’ve shared before on my old blog as well as in my portfolio. It’s special for a couple reasons. For starters, it was made at 3:30am in the National Park during a meteor shower. It was a great all night marathon that I remember well. To top that off, Parks Canada eventually requested a license to use this image for their 100th anniversary campaign featuring a different National Park across Canada for each hour of the day. Shockingly, the 2am to 5am slot was hard to fill. :-)

The point about resolution is that this photo was created with the original Canon 5D. It has a total of 12 MP of resolution but I lost some of that due to cropping and horizon straightening. The final print still measured 5 feet wide and found it’s home in both Ottawa and Toronto with a very close viewing distance.

Here are a few photos from that exhibit.

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What Exactly is PPI or DPI?

Prince Edward Island

I’ve been creating digital content now for almost 15 years and it remains to be frustrating how confused people are about the meaning of pixels (or dots) per inch. Either it be working for a web client, a magazine editor or with another photographer, the reference to the resolution of an image file in terms of pixels per inch continues to surface. What exactly does 72 pixels per inch mean? Nothing at all on it’s own because without a physical print size, that could literally mean anything.

DPI (or PPI) is the value that tells the printer how many drops of ink to place on a page for every inch of paper but it has very little to do with the actual files resolution. From a computers perspective, the only values that matter are the total number of pixels and a 4×6 inch print at 300dpi is the exact same file resolution as a 16.5×25 inch print at 72dpi. Note that I’m talking about the file resolution and not the print resolution. In both cases, the file itself has 1800×1200 pixels.

300 pixels per inch * 6 inches of paper = 1800 total pixels.
72 pixels per inch * 25 inches of paper = 1800 total pixels.

In my opinion, the dpi (or ppi) is simply the printed results of the true resolution. If someone asks for an 8×10 print at 260dpi, what they are really asking for is a resolution of 2080×2600 pixels. This same file would print 16×20 at 130dpi proving that without a width and height measurement, the dpi value by itself is simply a random number. And you can’t define a width and height using inches on digital displays.

Which brings us to the myth claiming the internet is 72ppi. It’s not true because no browser actually reads the ppi value and simply displays the image at 100% in relation to the grid of pixels known as your monitors resolution. That monitor resolution is a fixed value and unlike printing where you can control how many dots of ink (dpi) fall on the page per inch, you can not control the pixels per inch (ppi) of an image displayed on your monitor. If your destination is anything but print, talking dpi just complicates everything. Ignore it.

Unfortunately many popular sites are still teaching that 72 is required but today’s monitors are much more advanced than those original Apple 72ppi monitors. Take this chart for example. The monitor I’m currently typing on is set at 128 pixels per inch. If you are at all curious why 72dpi started in the first place, consider reading this article on text sizes.