Pixels & Digital Images

Hi Everyone! Today, I will start a serie of Teorethical Posts in order to solve doubts and to clarify concepts that – a priori – everyone knows. To this end, I will study each topic in depth and summarize all the relevant information about it. Then, I will try to explain each concept as simple as possible. 🙂 I hope you will find it useful!


At present, the – digital – image is everywhere. We have a large amount of devices that allow us to create, to process or to visualize content: tv, computer, laptop, smartphone, tablet, digital camera, reflex camera, scanner, printer,…

Whether for posting your photos in the social media or for choosing a new camera, we use words that are “oddly” familiar: megapixels, resolution, format, size, dimensions,…

Yes, it is odd since we have learnt them in our daily basis, not in a clear and precise way. So, let’s begin with some useful basic concepts.

What is a PIXEL?

A pixel is the basic unit that composes a digital image. This element is uniform and it can be in color or in grayscale. In addition, it contents the information about color, brightness and saturation. It is a non-dimensional magnitude, in consecuence, it doesn’t have a defined physical size. We need to have this clear for later explanations.

Then, digital images are created by a sequence of pixels that are organised in a grid system. So, pixels are structured in rows and columns. Its “level of organisation” defines the coherence of the information showed in the complete image. Then, If we have the following image: 1.280 x 720 pixels

  • Horizontal amount of pixels:                 1.280    pixels
  • Vertical amount of pixels:                         720    pixels
  • Total amount of pixels:                     921.600    pixels (product of 1.280 x 720)

This information is talking about the size in pixels of our image. That’s it!

It’s very common to use the term “resolution” while talking about the size of an image. However, resolution is a different concept from size. Anyway, both are strongly connected.

In fact, we tend to use the concept “resolution” when referring to the quality of an image. We will talk about it later.

Apart from this, you should know that the size of a digital photography is limited by the technical and physical capability of the device. This means that the final size of the image – in pixels – depends on the capacity of your camera or scanner.

Well, I think it‘s enough for this week! In the following posts I will explain concepts as: megapixels, density of pixels, resolution, physical size,…

This concepts may seem very simple but they will get more and more difficult. Stay tuned to keep learning! 🙂

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