Our clients often hear many terms such as "megapixels," "dpi," or "resolution" and wonder what the difference is between them. As photographers, it is our job to educate them on such terms in order to lessen the confusion when they are asking for certain sizes. However, if we do not understand not only the complexity but also the simplicity of what we are talking about, do we truly understand it at all?
The saying "if you can't explain it to a six year-old, you don't understand it yourself" comes to mind when explaining certain issues in photography. I recently read an article by Neil van Niekerk about the issues some photographers are having understanding how to export or resize an image for proper resolution. He wrote it best in his Tangents blog:
I live 20 miles at 65 mph outside New York. Yes, that sentence is pure nonsense. I live 20 miles outside of New York. That’s it. The complete description of the distance.
He is comparing this statement to the issues of pixels versus dpi.
I am sure everyone has seen image size requested as 600 x 400 pixels at 72 dpi. Or 300 dpi. When an image is described as 600×400 pixels, then the dpi (or ppi) value is of no consequence. It means nothing. It has become the superfluous 65 mph description.
image Courtesy of Neil van Niekerk
Diving into the math behind it is also not as scary as one might think. Understanding the basic multiplication sprinkled with some geometry (for aspect ratios) will help improve the conversation when speaking with clients. Some might see the word "math" and run for the hills, but it truly is quite simple and not to be feared. The post was a fantastic analogy to help any photographer understand the issues regarding the export of an image. Read more of his thoughts here.
And they say that Photography is an "Art Form." Looks like there be a WHOLE LOTTA "Sciences" involved as well. Mathematics is a form of Science, isn't it? ;-)
Lots of science. Look at the way we talk about stops, doubling and halving. And the Inverse Square Law.
But look on the bright side. There is a lot beauty in the science of mathematics. In fact, math is almost an art form at higher levels.
If I am asked to provide a file for printing an 8X10 at 300 dpi, it does not matter what dpi setting I use in Lightroom or Photoshop as long as I export at 2400X3000.
Except that it does matter. Not to me, or you, or to the printer, but to the people who do not understand the reality of the situation.
If I look at the details of a file on a Windows computer, it will show me the dpi setting (if I dig deep enough) used in Lightroom or Photoshop at the time of the export.
So if someone looks and sees it is 240dpi, they may very well not understand that only the pixel dimensions count. Worse yet, what if they see 72dpi or 96dpi?
So why not just set it to 300dpi and forget about it? That is what I do. I always export at 300dpi to save those people who are not photographers the pain of embarrassing themselves, or getting annoyed with me, or both. Why take the risk of annoying a client for such a simple matter just because you and I both know if is irrelevant?
There are definitely people in adjacent industries that know enough just to be dangerous, but luckily I have dealt with more people in my professional life that just don't know anything. I think the point is that explaining the concept is very easy and everyone should be able to understand 'total amount of dots that make up a picture.'
"ppi" not "dpi"...
It's amazing to me how many people in the industry do not understand this concept. It's all about the pixels! Yet I hear phrases like '3" file' pertaining to things being used on the web. It is not an accurate descriptor. To be honest for years I've wondered if I've had it right in my head and there is something I am missing.
It's a very small thing but I don't understand why people, even knowledgeable photographers, confuse dpi (printing) and ppi (file resolution).
I absolutely agree. It drives me crazy. I had a printer tell me it was the industry standard to use DPI instead of PPI. This may or may not be true but at least some of Adobe's products, such as InDesign, use PPI so it's not exactly universal.
The "dpi" is referred to when the image is printed on an offset printing press on paper. The general rule of thumb 2 x DPI = LPI. "LPI" is lines per inch which is the screened version of your DPI file. Newspaper print at a low LPI, maybe 80 to 110 Screen to compensate for the cheap and more absorbent paper they print on. Where as a high class Magazine will print at 175 or higher screen and on better glossy paper. The Higher the line screen the closer the lines are together to produce a sharper "Dot" so therefore the more "DPI" is often the better.
Look at newspaper and a Magazine under a magnifying glass and you can see the difference.
A whole other side to this is Converting your RGB file to CMYK to be printed (Additive and Subtractive colour theories).
None of the DPI rules apply on a monitor which is Pixels per inch "PPI".
Hi Brad. Thank you. You are, of course, correct. What I was referring to was when I hear a printer say something along the lines of "Be sure all your images are at least 300 DPI..." or when stock photo sites such as shutterstock or iStock describe an image as being '29.0" x 19.3" @ 300 dpi'. Clear they mean PPI and not DPI. I work with many printers every day and when I see something like this I clearly understand what the intended meaning is based on the context in which it is used, however, I have worked with a number of clients over the years that have gotten very confused by the mixed use of DPI and PPI. I just wish people would use these terms correctly across the board.
600 x 400 pixels at 72 dpi actually makes sense (assuming that they meant ppi). It means that, printer will interpret it as 8.3in x 5.5in.
The problem starts when people who don't understand it, make specific requests. On the other hand, clients who don't understand the concept, like to hire photogs with medium format cameras ;)
Yes but... "Why does it look good on my phone, but all fuzzy on Facebook"... I get that on all the time, not exactly sure how to answer other than "it's Facebook"
I mostly photograph corporate events and headshots. I'm finding many times I have different agendas between departments. The social media people need different specs than the advertising and communications people (yes they ideally should be working in harmony). What's still the case regardless of the department, is how few people working in either department know anything about the technical aspects of what they need. I'm not sure if it's because they are really sales and marketing - or that they may be writers at heart - but it's pretty frustrating explaining multiple times.