Nowadays, the resolution and pixel density of the display in a mobile device are one of the main marketing points. Find out what the PPI value affects.

Recently the company Samsung Galaxy S8 and Galaxy S8+, which feature an “unlimited” screen. The display has practically no frames and has a high resolution of 2960×1440 pixels and a pixel density of 570/529 PPI, respectively. In February, at the international exhibition MWC 2017, the LG brand announced a smartphone with a similar resolution and density of 564 PPI, and Sony announced a device with a 4K screen (3840 × 2160 pixels, 806 PPI). Clearly, high-resolution displays are the future.

When choosing a smartphone, many people pay attention to screen resolution, but pixel density is often left aside. Considering the development of screen technologies and developments in the field virtual reality, the ppi value also plays a big role in the quality of the display.

What is PPI?

The acronym PPI comes from Pixel Per Inch and is used to describe the pixel density of all types of displays, including cameras, computers, mobile devices, etc. Pixel density can be a measure of screen clarity, but there are other aspects to consider : his physical dimensions and distance to the eyes.

If you move the screen closer to your eyes, you will be able to see the pixels. If the device is on long distance from you, high density the pixels will not be particularly noticeable. Thus, the larger the display, the lower the PPI value.

Vision standard

Typically, a person's visual acuity is measured using the Snellen test, which was invented in 1860 for medical purposes. It is important to note that with this system, the ophthalmologist was trying to identify low vision, which is a medical problem. No patient ever complained of above average visual acuity.

This means that visual acuity of 20/20 is not ideal at all. This indicator means normal vision, in which a person can read a table at a distance of 3 meters.

The myth of 300 ppi

There is a myth that a person cannot distinguish pixels at a density of 300 ppi. In 2010, Steve Jobs used this statement during iPhone presentations 4, equipped with the then innovative Retina display with 326 ppi. This is partly true, but only for those users who have 20/20 visual acuity.

According to various studies, the human eye can distinguish pixels at densities of up to 900-1000 ppi.

What does pixel density affect?

The higher the pixel density, the sharper the image you will see on the screen. If earlier this did not matter much, then with the advent of the era of virtual and augmented reality the situation is gradually changing. You hardly want to see a pixelated image around you in virtual reality mode. The higher the resolution and pixel density, the more real the image. Moreover, this can be noticeable not only when using a virtual reality headset, but also when watching movies.

10.09.2012

Apple has never tried to be trendy. She always created these trends, and both buyers and competitors followed her. One interesting, from my point of view, trend of the couple recent years became the value ppi (Pixel Per Inch) - the number of dots per inch of the display. The indicator that informs about image clarity has become a mania.

The number of pixels per inch is indeed a very important indicator, which indicates how clear the image on the display will be. The larger this value, the less visible the pixels will be to the naked eye, and, accordingly, the less noticeable the steps on the inclined lines of the image will be. In absolute terms, the more dots per inch, the better. Although, it will not be possible to infinitely increase the pixel density by reducing their size - there are technological limitations, but they are still very far away. A completely different question: do we need displays with such a high ppi?

Before drawing conclusions and assessing the future, let's go back in time and see what pixel density displays of the past had. Back then no one paid attention to this parameter, so it is doubly interesting.
Let's discard CRT displays and start with the first LCDs. The typical size of the first models was 15 inches, and the resolution was 1024 by 768. The density in this case would be about 85 dots per inch. Then 17 and 19 inch models with a resolution of 1280 by 1024 appeared, their ppi turned out to be 96 and 86 points. Rare 22-inch panels of that time boasted a resolution of 1600 by 1200 and a density of 91 pixels per inch.

As you can see, all diagonals had a similar density, which was considered sufficient. At the same time, I think no one will argue that the pixels in such displays are visible, and the “ladders” on the fonts are very visible. But no one cared about this except video card developers, who, in the fight against the notorious ladders, for many years developed and improved anti-aliasing technologies that made it possible to mask this effect.

Modern home monitors have a slightly higher pixel density - and all thanks to the Full HD fashion. For example, a 21.5-inch monitor with a resolution of 1920 by 1080 is 102 ppi. A display ASUS laptop with a diagonal of 11.1 inches and a resolution of 1366 by 768, the density is 141 pixels per inch. It is most likely impossible to find more or less affordable solutions in a number of monitors for computers or laptops with a higher pixel density.

All home solutions range from 100 to 140 ppi. On TV the situation is even worse. For example, the pixel density of a 32-inch TV with Full HD resolution is 69 pixels per inch, while a 40-inch TV with the same resolution has only 55 pixels. And it’s scary to talk about large diagonals. For example, a 55-inch panel will have a density of 40 ppi.

But thanks to Apple, phones and tablets have become leaders in pixel density. The first iPhone, like its competitors, was not the sharpest by today's standards, having a 3.5-inch diagonal with a resolution of 320 by 480 pixels, and as a result a density of 165 ppi. A little later, without much noise, the first one appeared Sony smartphone Ericsson Xperia X1, which had a 3-inch display with a resolution of 480 by 800 pixels and, accordingly, a density of 311 ppi. But Sony was unable to properly “deliver” such high definition to the buyer, but Apple noticed the idea, took the initiative, and released the iPhone 4 with a display high definition, which is characterized by a resolution of 640 by 960 with a diagonal of 3.5 inches. The 330 dpi of this phone model, under the bright marketing name Retina Display, instantly won the love of customers. It was from this moment that everyone became interested in the ppi value. Apple itself, on the wave of success, has adjusted the new to Retina iPad generation, the display resolution of which was 2048 by 1536 with a diagonal of 9.7 inches. Its ppi value is 264 dpi, which, although less than that of the current generation iPhone, is twice as large as that of the iPad 2 and noticeably larger than that of most competitors, whose displays with similar diagonal sizes had a resolution of no more than 1280 by 800.

However, to the credit of their competitors, they quickly caught up with the gap, significantly increasing the resolution of the displays of their devices. In particular, the Samsung Galaxy Nexus boasts a resolution of 1280 by 720 on its 4.65-inch display with a pixel density of 316 ppi. A display ASUS tablet Transformer Pad Infinity has a resolution of 1920 by 1200 with a diagonal of 10.1 inches, which gives 224 ppi. But what’s most interesting is that they didn’t stop there...

The craze for pixel compression and creating displays with even higher PPI values ​​has reached almost all manufacturers. This is no longer even work to improve performance, but a competition. LG announces a 5-inch display with Full HD resolution and a ppi of 440 pixels. Toshiba responds with a 6.1-inch display with a resolution of 2560 by 1600 pixels, which corresponds to a density of 495 ppi. Well, the leader so far is the Japan Display consortium, which recently announced a 2.3-inch display with a resolution of 1280 by 800 pixels. Its density is 651 ppi. Amazing! But are displays with such high pixel densities necessary?

On the one hand, this definitely doesn’t make the displays worse – after all, you can’t spoil the porridge with oil. On the other hand, huge resolutions of small diagonals have disadvantages. The main disadvantage of all can be considered a significant increase in the load on graphics cards. For desktop computers this is not very critical - video cards with huge power consumption are the norm in this market. And increasing the resolution will allow you to abandon the heavy mode with anti-aliasing, since the “ladders” with which it is designed to combat will become almost invisible. But for mobile devices a significant increase in the number of pixels causes a huge impact on time battery life. Not only does the video card work hard to render such an image, which requires significant energy expenditure, but the display itself becomes more power-hungry as the number of pixels increases. So here you need to maintain parity between the developer’s desires and capabilities.

But it’s not just that – why complicate production and make more expensive products if the highest pixel density is simply not needed in some devices. For example, a 32-inch TV installed at a distance of more than three meters does not allow one to discern the difference in image clarity at HD and FullHD resolutions, while the pixel density in them differs noticeably - 49 ppi and 69 ppi, respectively. The reason is that from such a distance, we cannot see individual points - our eye simply physically cannot distinguish them. What if we make a TV of the same diagonal with the upcoming 4Kx2K resolution? With a resolution of 3840 by 2160, we get a density of 138 ppi, which is at the level of modern displays for laptops and desktop computers. It will be very convenient to work with such a monitor from a distance of 70-100 centimeters, but no one watches TV from such a distance! And a person sitting three meters from the device will again not see the difference between a TV with 4Kx2K and FullHD.

The conclusion from this is quite simple - a pointless increase in the number of pixels per inch will not improve the objective experience of displays at all. The important balance here is viewing distance/pixel density. As a starting point, we can conditionally take the ratio that is accepted in printing - 300 dots per inch. This density allows us not to notice pixelation in magazine photos. However, the paint spreads a little when applied to paper, which improves perception. Therefore, the optimal pixel density for displays should be 330 dpi. And this is if you place the device at the same distance as a newspaper or magazine. It’s worth mentioning here that we will not be talking about the minimum required resolutions and densities, but, on the contrary, about those that are needed to obtain an ideal image, similar in clarity to the same photograph printed in a glossy magazine, or the image on the screen of the latest iPhone.

That is, 330 dpi is optimal for smartphones, tablets, e-books. Let's take this as a starting point - the viewing distance is 50 centimeters, and the density is 330 pixels per inch. With this approach, optimal resolution for a 10.1-inch tablet it will be 2800 by 1800 pixels. As you can see, the iPad still falls short. But among smartphones there is already such a solution - iPhone 4 and 4S, their density is exactly 330 dpi.

Monitors and televisions no longer need such density, due to the fact that they are viewed from a greater distance. After simple calculations, we get the optimal result for home monitors, which on average are located at a distance of one meter. Considering that doubling the viewing distance requires half the density - the optimal ppi for them will be 165 dots per inch. That is, a resolution of 4Kx2K (which is 3840 by 2160 pixels) will be optimal for 27-inch monitors. And the now familiar FullHD looks optimal only on 13.3-inch displays. Well, a resolution of 2800 by 1800 pixels will be just right for 20-inch monitors.

As for TVs, it is worth considering that they are viewed from a distance of 2.5 meters - this is five times more than when using smartphones and tablets, as a result - the pixel density there can be five times lower, while maintaining the same image clarity . That is, a density of 66 dpi is sufficient for these devices. Now we calculate the ideal ratios of resolutions and diagonals. Dull 1366 by 768 pixels will look decent only on 23-inch displays. Modern FullHD will delight you with crystal clarity on 32-inch TVs. The same clarity, but at a resolution of 4Kx2K, can be achieved on displays with a diagonal of up to 65 inches!

PPI is an abbreviation for “pixels per inch”, literally meaning the number of pixels per inch. Naturally, the higher this value, the higher the pixel density; the pixels themselves are smaller in size, which results in a clearer picture on the smartphone screen (and the screen of any other device - tablet, monitor, TV, etc.). At low PPI values, you may see individual pixels on the screen, the image will be grainy, which is not very comfortable for the eyes. Typically phones with a low PPI value are budget models.

The full formula for calculating PPI looks like this: you need to take the square root of the sum of the squares of the number of pixels in height and width, and then divide the result by the screen diagonal in inches. That is, the formula will be like this:

Let's calculate using the iPhone 7 as an example, its resolution is 1334 by 750 pixels, and the screen diagonal is 4.7 inches, that is:

• 1334 squared = 1779556;
• 750 squared = 562500;
• Sum of squares, 1779556 562500 = 2342056;
• Taking the square root of 2342056 = 1530.378;
• Divide the resulting value by 4.7 = 325.6123;
• We round the value and get the number 326. This is the PPI for the iPhone 7.

What PPI value should the phone have?

You should not chase the highest PPI value. There are smartphone models on the market with a PPI value of more than 400, and even with more than 500. But the problem is that the human eye does not see the difference when the PPI value increases above 300. Of course, if you want, you can see the pixels up close, but with normal When used at a distance of 20-25 cm from the eyes, the screen will be very comfortable. In addition, processing very high resolutions leaves its mark on the operating time of the phone.

To understand such important and fundamental concepts in printing as ppi and dpi, you need to understand the basics of computer graphics in general.

First, you should understand that ppi and dpi are far from the same thing and they are very conditionally dependent on each other.

So, let's start with ppi, which stands for “pixels per inch”, which means “pixels per inch”. Since the metric system of measurement is adopted in the Russian Federation, it is good to remember that 1 inch is equal to 2.54 cm (although this is rounded, in reality it is 2.5399931 cm). Therefore, for us, a photograph of 10×15cm with a resolution of 300ppi means approximately the following: a photograph with side dimensions of 10×15cm in which there are 300px per 2.54cm. Which is equal to 118px by 1cm (this can be easily calculated by dividing 300 by 2.54 - the result can only be an integer, because there is no such thing as a half pixel).

The size of a given photograph can also be specified in pixels, as is often done in computer graphics. We multiply the physical size of the photo by the number of pixels that fit in one centimeter 10cmx118px=1180px and 15cmx118px=1770px and get the photo size in pixels 1180x1770px. As a rule, people who have little understanding of computer graphics get an idea of ​​the quality of a photo based on its size in pixels, which is a misconception. Because a 100x150cm image with a resolution of 30ppi will also have a pixel size of 1180x1770px. When printing such an image, it will be impossible to view it from closer than 20 meters, probably, otherwise it will cease to be an understandable image, but will turn into a set of multi-colored square pixels.

For a file intended for printing, the physical size of the image, coupled with its resolution, is important. Therefore, it is much more correct to indicate the physical dimensions of the file in cm and its resolution in ppi (if there were a generally accepted abbreviation using cm, then, of course, it should be used).

Pixel size is an abstract concept that can only exist in the virtual space of computer graphics. For a better understanding, let's take our 10x15px image at 300ppi and downsample it to 30ppi. Now, not 118px fits in one cm, but only 11px, although the image itself remains the same size.

This indicates that the pixel size has changed relative to the centimeter. That is, now it is formed from large elements, which will affect the quality of graphics. Accordingly, the smaller the pixels, the more of them will fit into 1 centimeter and therefore the more detailed the image will be.

There is a minimum image resolution for playback on a computer monitor and a minimum resolution for printing an image. Most likely, the minimum value of 72ppi for a monitor originates from the same English inch, which consists of 12 lines, which, in turn, consist of 72 dots. One way or another, but in printing (now mainly used only in offset - printing newspapers, magazines) there is such a value as lpi (Lines per inch - lines per inch), which, in general, promises only confusion and confusion among the concepts of ppi for an ordinary mortal , lpi and dpi, which we are now observing. The name “line” is conditional and in fact is also an analogue of a point or pixel. Which gets quite confusing. Therefore, we will not touch upon the term lpi at all, since it is rarely used today in digital printing and is completely understandable limited circle people who understand the processes of so-called rasterization (the main printing process from which more than 50% of printing success depends). Let's continue to talk only about ppi and dpi.

Now we are still talking about ppi - the resolution of a digital image: so, the minimum acceptable resolution for reproducing graphics on a monitor is 72ppi. All monitors have a resolution of 72ppi, so if you put your nose close to the monitor, you will be able to make out the pixels of the images. It doesn’t matter what size the monitor itself is - 15 inches or 17. It will always be 72px (recently monitors and screens with higher resolutions have begun to appear - HD, FHD, UHD... This only leads to the fact that now there is no single standard monitor resolutions and that the same image is on different monitors will look different in size. In any case, everything is still oriented towards 72px).

What happens when the image has a resolution greater than 72px, for example 350ppi? You will still be shown an image with a monitor resolution of 72ppi. To understand that the image has a higher resolution is possible only by changing the viewing scale. By increasing the scale of the image (bringing it closer), new details will be reproduced, previously invisible. When you zoom into an image with a resolution of 72px, these pixels will become clearly visible and the image will break up into multi-colored squares.

You can often come across this phenomenon when the resolution of an image is increased from the same 72ppi (for example, taken from the Internet) to 300ppi and asked to be printed in a large format. This demonstrates a complete misunderstanding of the term “permission” as such. There is no point in increasing the resolution of an image that was originally 72ppi. This will only increase its size many times over and when enlarged, it will produce a very blurry image instead of the pixel structure. There will be no increase in detail or quality.

When printing photographs, the minimum resolution is 150ppi. It is assumed that photographs can be viewed closely. A resolution of 150ppi when printing an image at a scale of 1:1 does not reproduce the pixel structure. However, you can often hear recommendations that the higher the resolution of the image sent for printing, the better the quality. This is a deep misconception. High image resolution only affects the computer processing time of the image before printing. 150ppi is quite enough for printing. The high resolution of 300 or more ppi, which the photograph originally had (for example, taken on a wide-format camera), is necessary primarily to increase the printing scale. For example, a 10x15cm photograph with a resolution of 300ppi can be enlarged twice to 20x30cm without loss of quality and quadrupled to 40x75cm for printing with acceptable quality, provided that the photograph is not viewed point-blank. As a result, image quality depends on the initial resolution settings. In the case of photography, camera settings. In the case of simply digital images - settings in the program for a new file. If you take a photo with a resolution of 300ppi, lower it to 72ppi, and then return it to the previous 300ppi, it will not return the same quality and detail.

Today, there are a number of applications that help sharpen low-resolution images. In particular, this can be done using Photoshop or using the most advanced program in this area, PhotoZoom Pro. The results can be truly impressive, but in any case it will be an artificial increase in sharpness, which, in fact, will not return detail to the image and, using the contrast of halftones, will create such an illusion. However, for most people this task is just right.

Now is the time to consider the question - what is dpi?

dpi - stands for “dots per inch” and translates as “dots per inch”. At first glance, the concepts of ppi and dpi are identical, especially if you remember that the term pixel refers to the minimum point of computer graphics, which, due to the characteristics of the virtual world, has the shape of a square. It seems that both concepts are talking about the same thing - dots per inch. But in fact, these concepts are in no way related to each other. To better understand the difference between them, it is best to remember that ppi as a term from computer graphics is the concept of the virtual world, and dpi is a term from printing, that is, the real world. To put it more adequately, ppi is the resolution of the digital image itself, and dpi is the resolution of the printing device. And although printing is impossible without graphics, these terms are in no way related to each other.

Once in the printing program (often these are just printer drivers), the file goes through a rasterization procedure. And in its essence it is similar to the pixel structure of digital graphics. A matrix (grid) is superimposed on the image. Here the term lpi mentioned above becomes relevant, but we will not touch on it, because for us it does not matter, if anyone is interested, you can read a good one. Then the same dpi comes into play, which characterizes the number of points applied to paper to draw one raster. That is, in this case, it no longer matters what the resolution of the image itself was in ppi - it no longer affects the dpi. dpi can be compared to the artistic style of pointolism in painting, when an image is formed from multi-colored dots. The smaller the point created, the more of them will fit per 1 inch.

The more dots that fit into 1 inch, the higher the quality of the print.

If, for example, you print an image with a resolution of 1440dpi from 40ppi on a 1:1 scale, you will get a very clearly printed image with high-quality drawn pixels that will be visible to the naked eye from a distance of 1m. On the contrary, you can print a high-resolution ppi image with a print resolution of 360dpi - the print will be blurry and grainy will be visible.

The term dpi is not the only one that characterizes the quality of a print. Also important when printing is the size of the applied drop, its shape (the more regular, the better the print), etc. With a low printing resolution (360 dpi), the density of the drops will be significantly lower and their size should be larger compared to a resolution of 1440 dpi. This will affect detail, precision and fineness of lines, as well as color saturation. Higher resolution affects print time - required large quantity passages. In large-format and interior printing, print resolution is set by both equal and unequal values. For example 360×360dpi, 360×540dpi, 540×540dpi, 540×720dpi, 540×1080, 720×720, 720×1080, etc. Why this is so - I admit, I don’t understand myself. But as a rule, everyone attaches importance only to the first value and therefore there are 4 main print resolutions: 360dpi, 540dpi, 720dpi, 1440dpi.

Today you can often find in large format printing offices requirements to provide images with the resolution specified in dpi. This is fundamentally incorrect and indicates the sufficient incompetence of the printers working there. An analogy is also often drawn between image resolution and print resolution, which also indicates a complete misunderstanding of the subject. The opposite extreme is when the image has a high resolution and the customer orders printing also in high resolution. But it makes sense to print this image in a low resolution, since this will not affect the quality of the print in any way, since the picture is, for example, simple text on a colored background, which will be clear even at a minimum resolution.

High printing resolution is relevant for halftone images (photos, drawings, etc.) The more complex the gradations and color transitions, the higher the resolution should be and the more perfect the screening procedure should be (but the screening procedure is entirely a headache for the printer, which does not concern customer).

With that, I’ll wrap up and wish you success in understanding such fundamental concepts in computer graphics and printing as dpi and ppi.

08/08/13- Vlad Rachkov

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When buying smartphones, monitors and other equipment that has a screen, we often hear about such a thing as ppi, but few of us can say exactly what it is and what it affects.

But in fact, this characteristic is one of the main ones when choosing.

We will tell you what the actual meaning of this concept is (after all, you can find many myths on this issue on the Internet). Go!

Theoretical page and calculations

The concept in question stands for pixels per inch, that is, the number of pixels per inch. Also pronounced pee-pee-ay.

It literally means how many pixels fit in one inch of the image that we see on the screen of a monitor, smartphone, tablet or other device.

This concept is also called the unit of measurement of resolution. This value is calculated using two simple formulas:
Where:

• dp– diagonal resolution;
• di– diagonal size, inches;
• Wp- width;
• HP- height.

The second formula is designed to calculate diagonal resolution and is based on the use of the famous Pythagorean theorem.

Rice. 1. Width, height and diagonal size on the monitor

To show how all these formulas are used, let's take for example a 20-inch diagonal monitor with a resolution of 1280x720 (HD).

Thus, Wp will be equal to 1280, Hp – 720, and Di – 20. Thanks to the presence of these data, we can calculate pi-pi-ai. First we use formula (2).

Now let’s apply these data to formula (2).

Note: In fact, we got 73.4 pixels, but there cannot be a non-integer number of pixels, only integer values ​​are used.
In exactly the same way, you can calculate the actual values ​​of the number of pixels per inch in any device.

To understand how much this is in centimeters, a more common value for our area, you need to divide the resulting number by 2.54 (there are exactly so many centimeters in one inch). So in our example it is 73/2.54=28 pixels. in centimeter.

In our example it is 73, and 25.4/73 = 0.3. That is, the size of each pixel is 0.3x0.3 mm.

Is it good or bad?

Let's figure it out together.

Is this quantity important?

Pee-pee-ay, based on the above, affects the clarity of the image that the user receives on his screen.

The higher the value of the indicator, the clearer the image the user will receive.

In fact, the larger this value, the fewer “squares” a person will see. That is, each pixel will be small, not large, and this will make it possible not to pay attention to it at all. The value of the characteristic can be clearly seen in Figure 2

Rice. 2. The difference between indicators is less and more

Of course, no one wants to have a picture like the one shown on the left on their smartphone or tablet. Therefore, when choosing such equipment, it is very important to pay attention to this characteristic. This is especially true when you buy on the Internet and do not have the opportunity to evaluate the picture with your own eyes and understand how clear it is.

Finding an indicator in the characteristics of the same smartphone is usually easy. It is usually contained in the "Display" section. An example can be seen in Figure 3.

Rice. 3. Indicator in the characteristics of the smartphone

Important! On the Internet you can often find information that ppi is more important than, for example, resolution or diagonal and some of these characteristics should play a more important role when choosing. This is not true at all. As we can see above, all these three concepts are inextricably linked.

Advantages and disadvantages

Number of pixels per inch has a positive effect on the clarity of the picture, and, accordingly, on its quality.

It will be much more pleasant for the user to look at an image with a higher indicator.

In Figure 2, the photo on the left has 30 ppi, and the photo on the right has 300. Below is another similar example.

But this concept also has disadvantages. In particular, we are talking about the autonomy of the device. Everything is quite simple - if the picture is clear, a smartphone, tablet or other device with a screen will not be able to work for a long time without recharging. You can even make a simple rule: the more pi-pi-ay, the shorter the battery life.

Of course, for a PC this is not a problem, since there the monitor is always plugged in, but for some phones this can become a big problem. Therefore, when choosing a device, be sure to pay attention not only to the number of pixels. per inch, and also on battery capacity!

Thus, we smoothly moved on to the topic of choice.

About choosing displays

There are several rules that will help you choose the display correctly, taking into account the pixels, they sound like this:

1Be sure to pay attention to the display type. The priority should be AMOLED, even better SuperAMOLED or OLED. Such devices will always be better than IPS, LCD and others.

Let's say we come to the store and see, for example, two excellent devices - Samsung Galaxy J7 and Xiaomi Redmi Note 3. Their price is almost the same, the second device, by the way, is more powerful.

The specifications indicate that Xiaomi has 400 ppi (for some reason, some write 400.53, but, as we said above, there cannot be a non-integer number of pixels). Samsung has 267 PPI and the resolution is correspondingly lower (1280x720 versus 1920x1080). The diagonal is the same - 5.5 inches.

But for some reason the picture is clearer on Samsung. And all due to the use of proprietary SuperAMOLED+ technology. You can see this for yourself if you pay attention to Figure 5.

2Try to find an opportunity to look at all the samples you have chosen in person. You can first look at their options on the Internet, and then go to an electronics store and see how they actually display pictures. A personal view in this case is simply irreplaceable.

3Pay attention to the battery. If we talk about smartphones, then to ensure long-term operation of the device with clear image(high ppi and/or good technology), then the battery capacity should be about 3000 mAh.

For tablets it should be even higher, since their diagonal is larger than that of phones

4Remember: the smaller the diagonal and the higher the pixel density (the number of pixels per inch), the clearer the image. Don't deceive yourself - you won't be able to achieve a very clear picture with a huge display and a small pi-ay value. It is important to maintain a golden mean here.

5It is also important to consider coverage. This way, matte screens will produce a less clear and saturated image, but will be more gentle on your eyes.

But glossy displays will negatively affect your eyesight, but the image on them will be much more beautiful. In this case, their ppi value may be the same.

This is mainly relevant for choosing monitors for PCs and laptops. If you work on a computer full time or even more, it is better to go with the matte option.

All this will allow you to choose the most suitable display for yourself.

Results

ppi or pi-pi-ai is the pixel density or the number of pixels per inch of an image. To convert the figure to centimeters, you need to divide it by 2.54. There cannot be a non-integer quantity, only a whole.

The higher this is shown, the clearer and more pleasant the image will be to look at. When choosing smartphones, tablets, PC monitors, laptops and other equipment that has a display, it is very important to pay attention to this indicator.

But it is not fundamental. It is also important to look at the technology and screen coverage. Also, be sure to look at the battery capacity and maintain a happy medium between the number of pixels. and screen size.