Check Your Megapixels


One of my photography instructors used to say, “if your photo sucks, blow it up bigger and put it in a nice frame”. That’s probably why they serve wine at most art shows…

Have you ordered enlargements and they looked terrible? Didn’t you just want to slap the 18 year old punk behind the counter at Walget when he mumbled “pixelation” and you had no idea what he called you? Let’s take a look at why this happens and better yet, how you can prevent it the next time…

What the heck is a pixel?
Here is a little useless knowledge for you. The word “pixel” somehow came from “picture element”, so hold onto that one for your next trivial pursuit jam…Anyways, to create an image, film cameras exposed frames of (duh) film to light. Digital cameras replaced the film medium with a sensor that records light in the same way, but collects that information into tiny blocks called pixels. Megapixel (MP) is the unit of measure to express how much of that data (how many blocks or pixels) can be recorded by a camera’s sensor. So a 6 megapixel camera’s highest quality image measures 3000 x 2000 pixels (actually, it’s 3008 x 2000, the dimensions are rounded). Higher megapixel cameras produce images that contain more blocks of information (pixels) in their image than those from a lower megapixel camera…..

What does this have to do with enlargements?
Plain and simple, the higher the number of pixels in an image, the smaller each pixel will be in that image since you are cramming more data into the same size image! When you blow up an image, you are stretching the size of each pixel. The smaller each pixel is to begin with, the more you can blow up or stretch that image before you start to see the pixels (the dreaded pixelation!).

So does that mean my camera sucks?
Maybe, but don’t throw it against the wall just yet . You see, all digital cameras have settings that affect the size of the actual image recorded. So you may not even be using all of your megapixels! Lower quality /size settings allow you to fit more images on each memory card. Just remember though, once you take the picture you can’t add more data. So quit being cheap, buy a bigger or additional memory card and use the highest quality settings for your camera!

Where do I find this quality setting?
In your user’s manual! Sort of kidding. It’s impossible to cover every camera here, so you should keep your manual handy. The setting you are looking for will be called quality, or size and will be expressed in pixels (3702 x 2304 for example). As an example, let’s look at the settings on a Canon SD750, which is a 7MP camera. For this particular model, the size settings can be found under Function Menu/Compression/Recording Pixels:

  • Large (3072 x 2304 pixels) = full 7MP
  • Medium 1 (2592 x 1944 pixels) = down to 5MP
  • Medium 2 (2048 x 1536 pixels) = should have saved some money and bought a 3MP camera
  • Medium 3 (1600 x 1200 pixels!) = 2MP??? Just use your camera phone!
  • Small (640 x 480 pixels!!) = seriously? Why did you even buy a digital camera???

As you can see, you spent a lot of money for a 7MP camera in this case, but you may only be using a fraction of those pixels!

Side note…we are NOT talking about the JPEG settings for compression yet, we will talk about those in another class, but for now set that to the highest quality as well.

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