May 21, Common Questions about Pixels and Resolution

What are the common questions about pixels and resolution? Here are some answers!

Well… When I talk to people about video and digital cameras I always get questions on this subject…

  • What is image resolution?
  • Are pixels square?
  • What is a pixel made of?
  • What do pixels have to do with image resolution?

Well… Here are some answers to these questions and a few others!

One of the Most Common Questions about Pixels Is… What Is Pixel?

What is a pixel?

What is the definition of the word Pixel… Well…  “Pixel” is a contraction of the words “picture” and “element”. It is a single and discrete point of color in a digital image.

* You could also say that it is the
smallest  single component of a digital image.

The word is mainly used however as the main indicator of the resolution of the digital image itself.

The word was actually coined earlier but… It was first talked about in 1965 by Frederick C. Billingsly, a JPL
scientist. The word was used to describe the picture elements of the video
images being sent back to earth from
space probes to the Moon and Mars.

Are There Are Two Kinds of Pixels?

Are their two types of pixels?

One of the most common questions about pixels I’ve gotten is… Are there two kinds of pixels?

Well… Yes and no… It depends on if you’re talking about display screens or… if you’re talking about the image sensor in your digital camera. Let me explain…

* When were talking about pixels on a display screen… Such as a TV screen… 

Video display monitor

We are then talking about a small area of illumination on the screen and, of course, all of these small areas (pixels)… put together… form the picture.

The screen itself is a two-dimensional grid and the number of the
small areas of illumination (pixels) on the grid determines the resolution of the
image projected on the screen. The number of pixels on the screen are broken down into what are essentially numerical categories such as Standard Definition, High Definition, 4K etc. 

normally when were talking about pixels (in this way) were talking about
the resolution of a digital image as displayed on a screen. 
But… What are pixels in a camera then? Well… I’m glad you asked!

* If we are talking about pixels in relation to digital cameras or camcorders specifications…

Camera image sensor

Then we are talking about the camera’s image
… The image sensor’s “pixels” are an actual physical thing (device) embedded in the image sensor
that are called “photosites” or “photo cavities“.

a digital camera, just as on a display screen, we equate pixels to
resolution and rightfully so… but… 
Just remember were talking about a
slightly different thing when were talking about pixels and digital
camera or camcorder image sensors.

Are Pixels Square?

What is a pixel?

When you see a pixel drawn on the grid it’s usually represented as a square or rectangle.

But… electronically it doesn’t have to be rendered as a square or rectangle. It can be rendered as a dot, or lines etc. it just depends on how the display device… Your…

  • CRT,
  • LCD,
  • LED screen etc. 

… handles the information.

How Big Is a Pixel? What about Pixels in Resolution?

How big is a pixel?

Okay… What is the size of a pixel?  

Well… This can be a source of confusion… Maybe, not so much for the videographer… But for the graphic artist or photographer because, of course…. They sometimes need to convert pixel resolution to DPI if they want to get an idea of how good the resolution of their images will be when they print them.

* The digital image (made up of pixels) in reality is
actually just a digital file containing information that can be
converted into an image when sent to the proper display screen. 

How big is a pixel? The display screen, of course, can be adjusted for
higher or lower resolution(more or less pixels) but…

A pixel itself has
no set size.

What Do Pixels Have To Do with the Image Resolution?

Pixels and image resolution

Here’s another common question about pixels and resolution. The relationship of pixels and resolutions is, of course, that…

* Resolution is the number of pixels in an image. 

You’ll find that it’s identified by not only the total number of
pixels in the image but… by the height and width of the image also.

For instance…  If
you want to calculate the megapixels of the image… 
Just multiply the
number of pixels in the width of the image by the number of pixels in
the height of the image… and you will get the megapixels. 
For example an image that was 2048×1536 would equal 3.1 megapixels.

For the graphic artist or photographer the higher the resolution the image is shot in… then the higher the DPI (dots per inch) that can be used when printing the image as…  higher resolution means more information to work with… Which equals finer detail.

What Are Pixels in Inches?

you are a graphic artist or photographer and want to delve into this a
little deeper here’s a site that has an image size calculator/converter
where you can get an idea of how a digital image in pixels will print,
resolution wise, when you output it on your printer.

Picture Resolution… Film Versus Digital…

Digital resolution versus film resolution

One of the common questions about pixels and resolution that I get from time to time is… how does digital camera resolution relate to film resolution?

Film is going the way of the dinosaur but… It’s interesting to compare film  to digital cameras as far as resolution. 

For 35mm film it is widely considered that the resolution falls somewhere between four and 16 million pixels.

That’s, of course, depending on the type of film you use plus some other
factors but as you can see… You get this wide range of 4 to 16 million.

But you can also see from the above figure that… Digital cameras
that shoot at a resolution of 16 megapixels on up will give you what
you’re looking for as far as resolution if you are shooting in what
would be considered a 35mm format.

Megapixels versus film ISO speed

Now… If you’re shooting medium format … larger than 35mm or large (4×5
inches (100 x 127 mm) on up… film… Well…

Using the same formula
as above the research has shown that film has the potential to capture
somewhere in the neighborhood of 400 megapixels per image…. Quite a jump!

filmmakers, videographers and photographers are more than okay with the
resolution that a digital camera can capture but… Medium and large
format film cameras still have their use if you want the best resolution

What Is a Megapixel?

What is a megapixel?

A megapixel is the equivalent of approximately 1 million pixels.

This measurement is used mainly to describe the size of the image
in a digital camera and is one of the main selling points in the
marketing of…

  • Smart Phones,
  • Camcorders and
  • Digital Cameras.

little point on megapixels… Don’t confuse the
pixel count… How many
megapixels a particular image sensor has…With the quality of the
image it will capture. 
Megapixels are a factor but… Just one of a few that go into capturing a clear, sharp and colorful image.

quality of the image your digital camera, camcorder or smart phone will
produce depends on…

  • The actual size of the image sensor,
  • Optics (lenses),
  • Circuitry,
  • Firmware and
  • Digital storage media type.

Each of these factors play a role in the ultimate sharpness and clarity of the image that you capture.

The amount of megapixels is a great selling point… and is, of course… important but…The lower quality of an image shot with a smart phone
(using a minuscule sensor) as compared with the same image shot with a
higher-end digital camera is apparent… Even if the sensor’s megapixels
listed in the specifications for each are about the same.

not to say your smart phone can’t capture excellent images… It is just
that digital cameras with their larger sensor size capture an image with
more fidelity.

So… There are the answers to some of the common questions I get about pixels and resolution… I hope you found them helpful!

Have fun…!  Dan (Editor)

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