When looking at screen technologies, the words “definition” and “resolution” are often confused. However, these two overused terms have many differences. This little file explains what characterizes each concept and will help you, incidentally, to shine in society.
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The place of new technologies in our daily life sometimes forces us to acquire new technical knowledge. Difficult indeed to find oneself in the middle of the marketing terms of the brands. Regarding screens (smartphones, tablets, TV), we regularly see manufacturers using the terms “definition” and “resolution” to highlight the quality of their equipment.
Don’t you know the difference between the two? Don’t worry, the manufacturers themselves sometimes confuse the two terms. To make matters worse, the presentation conferences are held in English. Gold, in Shakespeare’s language, the two notions translate into “Resolution”.
If some people use the formulas more and more “Display resolution” (definition) and “Pixel density” (resolution) to separate the two concepts, difficult for the consumer to distinguish between them. To see more clearly, we have prepared a small explanatory file which, we promise, will not knot your brain.
Definition: the number of pixels
What do HD, Full HD, QHD and 4K have in common? Good question, thank you for asking it. All of these terms speak of one and the same thing: screen definition. The definition is the number of pixels present in a slab. To find out the definition of a screen, multiply the number of pixels placed on a width by the number of pixels placed on the height. Thanks to this scholarly calculation, we get the definition of the screen.
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For example, a QHD panel in 16: 9 format is made up of 2560 pixels in width and 1440 pixels in height, making a total of 3686 400 pixels. A 4K panel displays 8,294,400 pixels (3,840 x 2,160 pixels).
Manufacturers have recently communicated on Full HD + or QHD + definitions. This little “+” appeared while smartphones were gradually integrating new screen formats (18: 9, 19.5: 9, 20: 9, 16:10). For these particular cases, the number of pixels present on the width and the height change.
Thus, a QHD + screen in 18: 9 format is made up of 2880 pixels in width and 1440 pixels in height. If you are lost remember that a QHD definition has 1.6 times more pixels than Full HD definition, 4K / UHD four times more. To see more clearly, we have put together a little summary table for you.
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Watch out for energy consumption!
A nice screen is good, you still have to be able to power it. You may have noticed that smartphones with QHD displays have the latest generation processor and GPU.
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This is simply explained by the resource requirement of these slabs. The higher the definition, the more power and energy the screen needs. for example a QHD panel requires 1.5 times more power than a Full HD panel. And we’re only talking about a screen with 60 Hz refresh rate. The 90 Hz and 120 Hz screens are even more demanding.
Manufacturers must then optimize all of these parameters while maintaining adequate autonomy. To design its Galaxy S20 Samsung has chosen to limit the refresh rate of 120 Hz to Full HD definition. Combining QHD and 120 Hz would have had a significant impact on autonomy already average.
Resolution: pixel density
The resolution is the ratio between the definition of the slab (number of pixels) and its size (in inches). In France, it is expressed in pixels per point (PPP), English speakers speak of pixels per inch (literally pixels per inch). The higher the result of this report, the better the resolution.
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You can have fun with your calculator to calculate the resolution. But you risk getting annoyed with the conversion game. We therefore recommend that you use free, more practical online tools, as PPI Calculator. Enter the definition, the screen size and you will get the resolution.
For example, we compared the resolution of a 6.9-inch smartphone and a 12.9-inch tablet, both with QHD resolution (2560 x 1440 pixels). We got a resolution of 425 ppi for the smartphone and 227 ppi for the tablet.
What do these scores mean? Simply that for the same definition, the screen of the smartphone is more comfortable than that of the tablet. As the pixel density is lower, the human eye can more easily distinguish them. This difference is particularly noticeable in texts or games. This is not to say that racing for the best resolution makes sense. Because the human eye also has its limits.
What does the human eye perceive?
Contrary to what you might think, the human eye can no longer tell the difference between two resolutions above a certain threshold. Apple, whose Retina technology fixes the resolution at 300 dpi, believes that the human eye can no longer see pixels beyond this limit. In reality, it’s not all that simple.
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It all depends on the view of each user and the distance from which they view their screen. Experts believe that a correct resolution is between 300 and 400 dpi, well below the screens of some smartphones, not just the most upscale. Below 300 dpi, an average user can distinguish pixels by getting closer to the screen. Crossing the 400 dpi mark is useless since the screen will be more resource and energy intensive without providing more comfort.
However, there are two exceptions. Some superheroes are able to distinguish pixels up to 600 dpi by gluing the screen, without using a magnifying glass. Mostly, virtual reality enthusiasts will see the pixels, the lens of their helmet magnifying the image. But these cases do not really reflect the usage of the general public.
Now you know the difference between definition and screen resolution. Not only can you no longer be destabilized by marketing speeches, but you can also shine at the next family dinner.
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