What are megapixels in a camera?

Have you ever asked yourself, what are megapixels?  Whenever anyone talks about cameras, the term megapixels is always thrown around.  This got me thinking that there may be people out there that don’t know what a megapixel is.  In fact, the question should really be….  What is a pixel?

What is a pixel?

– A pixel is the smallest element of an image that can be individually processed in a video display system

Now, before we start to get confused on “megapixel” VS “pixel”, let’s clear something up.

Mega means million.  So the difference between a pixel and a megapixel is the quantity.

1 pixel is exactly that.  1 Pixel.

1 Megapixel is 1 Million pixels.

So now that we have cleared that up, let’s get to the guts of what a pixel is.  In its most basic form, a pixel is a (tiny) dot on a screen.  This dot can vary in color and in brightness.  When we put a lot of these dots together with all their different colors and brightness, they form a picture. 

Let’s look at the picture below.  This is a cityscape shot of Sydney.  You can make out the harbor bridge, the Sydney opera house, and all the buildings around it.

At this point, all you see is the actual photo and no pixels.  The reason for this is that the pixels are incredibly small and you are not supposed to see them.  When we look at a collection of pixels we only see the overall picture.

Now let me zoom into the picture and see what it looks like when we zoom into the opera house.

As we zoom in to a small section of the photo the pixels become visible.  You can now see how the image is actually made up of these little square blocks.  Each one of those blocks is a pixel.  Let’s zoom in a little more to see it even more clearly.

The pixels are now very clear so see.  All digital images are produced this way.

So how are these images formed?

When we moved away from film cameras, we replaced the film with a digital sensor.  The sensor inside your camera is made up of millions of photosites.  If you looked at a camera sensor through a microscope you would see millions of these little photosites  There is a photosite for each pixel.  Simply put, each photosite records the brightness and amount of color and then sends this information to its corresponding pixel.  The pixel then recreates the color and brightness and.  When you do this with millions of pixels, you end up with a photo.

If you have ever walked right up to a billboard, you would have noticed that the image on that billboard is actually made up of millions of little dots of various colors.  The concept is exactly the same.

Because the pixels are so small, when you look at all of them put together, you don’t actually see the pixels.  Instead, you only see the photo.

In theory, the more megapixels (millions of pixels) that a camera has, the clearer the picture should be because you have more pixels to make up the picture.  In theory, the more megapixels you have, the bigger your prints can be before you start seen pixels in your photo.  I say “In theory” because there is more to it than just the number of pixels.  The quality of the pixel can be equally if not more important.  But, we’ll leave that for another day.

So now when anyone starts talking about megapixels you will know exactly what they are talking about.

Dan Cantero

Dan is a commercial photographer based in Sydney, Australia and the creator of www.ministryofphoto.com

To check out Dan’s work visit www.dancantero.com.au