what is a pixel
definition of megapixel

What is a pixel?

The definition of pixel is simple, but why should you care?

Certainly, with digital photography it's important to understand a few photography definitions, but do you really need to understand how a pixel works. 

Knowing a few digital photography terms will help you make better choices when comparing cameras and accessories.

And yes, even help you take better digital photos. 

The word "pixel" is actually a shortened combination from the two words; picture and element.

The combination of two or more words and their definitions into a new word is called a portmanteau.

Diagram of a pixel

Red + Green + Blue  

These 3 colors of light combine to form all colors of the colors spectrum.

With respect to a digital camera sensor, the term pixel usually refers to a photosite which is a combination of red, green, and blue elements that combine to form one color point. 

definition of megapixel

pixels on camera sensorDigital Camera Sensor

A megapixel is one million pixels.  A digital camera sensor that has an 8.2 megapixel sensor has about 8.2 million or 8,200,000 pixels.  Interestingly enough, one of the first digital cameras I held in my hands had only .03 or 30,000 pixels.

It can be confusing because we also refer to those individual points of light on an LCD or TV screen as pixels. What is important is that you don't fall into the trap called the megapixel myth: "More Megapixels Must Mean Better Photos"


the megapixel myth

Is a 16 megapixel camera better than a 12 megapixel camera?  Generally it can be, sometimes, but not always. The actual size of the individual pixels matters. Bigger pixels are better at collecting light.

How closely they are spaced together matters. If your sensor has a lot of space in between individual pixels

Here's the deal: There are too many variables to make a hard and fast conclusion about image quality based solely on the number of pixels built onto a sensor.

Here's what I mean.

A.  A cell phone camera with a 30 megapixel sensor can not match the quality of a DSLR camera with a 12 megapixel sensor.  The photo sites on the cell phone (even though there are more of them) are tiny and can't collect light as efficiently as the much larger photosites on the bigger DSLR sensor camera.

B.  A Foveon sensor doesn't need as many pixels to match the quality of the more well known mosaic sensor.  A Foveon-sensor camera with a 10 megapixel count might match the quality of a typical DSLR camera with a 12 megapixel count sensor.

Foveon vs mosaic sensor diagram

It's not the definition of what is a pixel that matters. The overall size in width by length of a sensor is the most important factor in terms of image quality.  Also important is the size of the individual light-collecting photosites, how close they are to each other, as well as the camera's internal processor that converts that light information into a viewable image.


So, How Many Pixels Do you Need

photo printerPhoto Printer

It's 2017. This post has been updated and it's not a far cry from reality to say that all new cameras have enough pixels to satisfy your every pixel popping need. You used to be guided by looking at how you were going to use your digital photos afterwards.

If you were using your photos just for the internet or sharing with friend via email, a low megapixel count was adequate. If you were printing to a nice small snapshot size you needed more megapixels to get a decent quality.

Large poster-sized prints required image files from high megapixel cameras. Not any more. Even budget digital cameras have 8 megapixels or more. If you fill your frame with your subject, you've got plenty of pixels to produce really good quality.


3 practical ways to compare digital cameras and their megapixel totals

There are three primary ways to find out if the camera you considering has the right sensor for your needs.

1.  Read the technical reviews on sites like dpreview or Steves-Digicams.  Although some readers find the reviews a bit too technical and don't like all of the ads.

2.  Take a chance and just buy one and see if you like it. Find out the return policy of the vendor you buy from first.  Another option would be to re-sell it on ebay, at a small loss, and try another camera model.

3.  The third way is my favorite.  I learn a lot from other buyers of the cameras and accessories that I am considering. Doesn't it make sense to get a wide variety of opinions from people who have purchased and used equipment first?

First, I confess that I have spend many hours with method 1.  I actually enjoy reading the technical reviews, but after all, I am a camera geek. I've also sold plenty of used camera gear on eBay, but not so much anymore.

No, I find the most useful information about photography equipment (and many other products I buy) from photographers who have purchased and used the camera already. These are every day people like you who want to get the right product, at the right price.


Digital Camera Reviews Written By Consumers and
Not Professional Camera Reviewers

In my opinion the feedback from regular folks like you and me is very valuable.  The readers of the Better Digital Photography Tips web site know I like to find practical answers, not necessarily the most technical. 

When people are searching for a definition of what is a pixel or an explanation of pixel or the definition of megapixel, it is usually because they want to make an intelligent decision on comparing digital cameras and choosing the right one.





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Shoot more photos.

Watch less TV.

Bruce


links related to what is a pixel:


Full-frame Sensor

Tips for taking better digital photos

Information about Pixel on Wikipedia

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