You’ve probably heard “The more megapixels a camera has, the better the pictures it will capture.” For the most part, this is a myth. Generally speaking, once you hit the 5 MP mark, there are far more important things to consider. For example, you have the lens, the aperture, sensors, zoom, focus, and tons of other things that when combined will determine the quality of a photo. But what about when it comes to Printing said photos? The first thing we need to do is explain a few terms.
MP (Megapixels) A pixel is a smallest possible element of a digital picture. A megapixel is 1 million pixels. A pixel is not necessarily a square, though for ease of use most photo imaging software suites will render them as such; it is more easily referenced to as a measurement of area.
Resolution This is the number of pixels in height and width across a screen or digital image. For example, an image with a resolution of 1024 x 768 would have 786,432 pixels or 0.8 megapixels (rounded up).
PPI (Pixels Per Inch) Pixels per inch is the density of pixels over a 1 inch area. You can determine the PPI of a device by taking the resolution and dividing it by the physical width and height of the device. 300 PPI is generally the highest aimed-for density, as the human eye cannot tell the difference in image quality beyond that. Displays generally use subpixels of RGB color to generate actual pixels.
DPI (Dots Per Inch) In terms of physical printed images, dots per inch is the density of individual ink dots that a printer is able to generate. In comparative terms to PPI, you can’t compare the two. DPI is for printed photos, and PPI is for digital displays. In terms of conversion from resolution, a printer can treat pixels as dots and in such case a higher DPI setting would result in higher quality but also in a smaller picture. Although a printer may say “Can Print up to 2400 DPI,” that doesn’t mean that you’ll actually ever print anything with that high of a density.
Now that we’ve got that covered, let’s use an example. Say you have a camera that captures at 5 megapixels. This means you can capture pictures at a maximum resolution of 2600 x 1900 (4,940,000 pixels). When printing, the untrained human eye doesn’t distinguish quality difference in prints over 300 DPI, but usually a 250+ DPI print is acceptable to most people.
Extra pixels doesn’t mean extra quality!
Now there are a few things to remember –if your camera can capture pristine quality photos, you can use a lower DPI without noticing much of a difference. If your camera doesn’t have a good enough lens, etc.. then it will take pictures in which some of the pixel groups will be blurry, aka the wrong color. Blurry pixels are useless pixels! As a result, all of those extra megapixels the camera manufacturer was advertising are completely worthless, and you’ll end up with horrible photos regardless of how high the DPI is. Not to mention, blurry high resolution photos will quickly fill up your SD card.
Sounds good, give me the quick fix!
Alright, now for the sake of my own sanity writing this. Let’s assume that you have a decent camera with other features than just “lots and lots of Megapixels.” Let’s also assume that you have a decent printer. You can use the chart below to figure out what quality size photos you can print based on how many megapixels your camera prints at. I’ve listed Bad Quality at 72 DPI, Poor Quality at 150 DPI, and High Quality at 300 DPI. Ideally you would want to print at 150+ DPI, but again this depends on your camera’s (and the photographer’s…) ability to take quality pictures. Alternatively, if you have a size that isn’t listed you can use the online megapixel calculator. Questions, comments? Leave one below and let us know what you think! Thank you. I have a Canon 60D – 18 megapixels. When I go to crop in Lightroom it offers 4×6 and 5×7 and my question is are these the native sizes (ratios) that come out of cameras? Does that make sense..? I guess when I see at the print shop 8×10 and 8×12 then there is two different sizes by height but the same width. What I’m wondering is which is the size out of the camera? thanks for the help… Rob Comment Name * Email *
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