Disadvantages of amoled displays What is color gamut and why is it the subject of much speculation

By 2018, the rivalry between screen technologies boiled down to only two decent options left on the market. TN matrices have been supplanted, VA in mobile devices have not been used, and something new has not yet been invented. Therefore, the competition has developed between IPS and AMOLED. It is worth recalling here that IPS, LCD LTPS, PLS, SFT are the same as OLED, Super AMOLED, P-OLED, etc. are just varieties of LED technology.

On the topic of which is better, IPS or AMOLED,. But technologies do not stand still, so in 2018 it will not be superfluous to make adjustments and make an analysis taking into account today's realities. After all, both types of matrices are constantly being improved, getting rid of some shortcomings, or these disadvantages become less significant.

Which is better for a smartphone, IPS or AMOLED, now let's try to find out. To do this, we will weigh all the pros and cons of each of the technologies in order to identify the absolute leader based on the preponderance of the strengths or, taking into account the specifics, to decide which is better in specific conditions.

Pros and cons of IPS displays

The development and improvement of IPS displays has been going on for two decades, and during this time the technology has managed to acquire a number of advantages.

Advantages of IPS matrices

IPS panels are the best among all types of LCD panels due to a number of advantages.

• Availability... Over the years, the technology has been massively mastered by many companies, making the mass production of IPS screens inexpensive. The cost of a screen for a smartphone with FullHD resolution now starts at about $ 10. Thanks to their low price, these screens make smartphones more affordable.
• Color rendering... A well-calibrated IPS screen reproduces colors with maximum fidelity. That is why professional monitors for designers, graphic artists, photographers, etc. are produced on IPS matrices. They have the widest range of tones, allowing you to get realistic colors of objects on the screen.
• Fixed power consumption... Liquid crystals that form a picture on an IPS screen consume almost no current, the main consumer is backlight diodes. Therefore, the power consumption is independent of the image on the display and is determined by the backlight level. Due to the fixed power consumption, IPS screens provide approximately the same autonomy when watching movies, surfing the web, writing communication, etc.
• Durability... Liquid crystals are almost unaffected by the aging process and wear and tear, so in terms of reliability, IPS is better than AMOLED. Backlight LEDs can degrade, but the service life of such LEDs is very long (tens of thousands of hours), so even after 5 years the screen almost does not lose its brightness.

Disadvantages of IPS matrices

Despite the significant advantages, IPS also has disadvantages. These disadvantages are fundamental, therefore, they cannot be eliminated by improving technology.

• Black purity problem... Liquid crystals that display black do not block 100% of the light from the backlight. But since the backlight of the IPS screen is common for the entire matrix, its brightness does not decrease, the panel remains backlit, as a result, the black color is not very deep.

• Low contrast... The contrast level of LCD matrices (about 1: 1000) is acceptable for a comfortable perception of the picture, but according to this indicator AMOLED is better than IPS. Due to the fact that the black is not very deep, the difference between the brightest and the darkest pixel in such screens is noticeably less than that of LED matrices.
• Long response time... The pixel response speed of IPS panels is low, about ten milliseconds. This is enough for normal perception of the picture when reading or watching video, but not enough for VR content and other demanding tasks.

Pros and cons of AMOLED displays

OLED technology is based on the use of an array of miniature LEDs located on a matrix. They are independent, so they offer a number of advantages over IPS, but not without their drawbacks.

Benefits of AMOLED matrices

AMOLED technology is newer than IPS, and its creators have taken care of eliminating the disadvantages typical of LCD displays.

• Split Pixel Glow... In AMOLED screens, each pixel is itself a light source and is controlled by the system independently of the others. When displaying black, it does not glow, and when displaying mixed shades, it can produce increased brightness. Due to this, AMOLED screens demonstrate better contrast and black depth.

• Almost instant reaction... The pixel response speed on the LED matrix is ​​orders of magnitude higher than that of IPS. Such panels are capable of displaying a dynamic picture with a high frame rate, making it smoother. This feature is a plus in games and when interacting with VR.
• Reduced energy consumption when showing dark tones... Each pixel of the AMOLED matrix glows independently. The lighter its color, the brighter the pixel, therefore, when displaying dark tones, such screens consume less energy than IPS. But in the process of displaying white AMOLED panels, they show a similar, or even greater than that of IPS, battery consumption.
• Small thickness... Since AMOLED matrices do not have a layer that scatters backlight light onto liquid crystals, such displays are thinner. This allows you to reduce the size of the smartphone, while maintaining its reliability and without sacrificing battery capacity. In addition, in the future, it is possible to create flexible (and not only curved) AMOLED matrices. This is not possible for IPS.

Disadvantages of AMOLED matrices

AMOLED-matrices are also characterized by shortcomings, and there is only one culprit for most of the troubles. These are blue LEDs. Mastering their production is more difficult, and in terms of quality they are inferior to green and red.

• Blue or PWM... When choosing a smartphone with an AMOLED screen, you have to choose between pulse width control of brightness and blueness of light tones. This is due to the fact that with continuous light, blue subpixels are perceived more strongly than red and green ones. This can be fixed by using PWM dimming, but then another drawback pops up. At maximum screen brightness, there is no PWM or the adjustment frequency reaches about 250 Hz. This indicator is on the border of perception and almost does not affect the eyes. But with a decrease in the backlight level, the PWM frequency also decreases, as a result, at low flicker levels with a frequency of about 60 Hz, it can lead to eye fatigue.

• Burnout blue... There is also a problem with the blue diodes. Their lifespan is shorter than green and reds, so color distortion may occur over time. The screen turns yellow, the white balance shifts towards warm tones, the overall color rendition deteriorates.

• Memory effect... Since miniature LEDs are prone to fading, areas on the screen that displayed a bright, static picture (such as a clock or a light-colored network indicator) can lose brightness over time. As a result, even if the element is not displayed, the silhouette of this element is visible in these places.

• PenTile... The PenTile structure is not a fundamental disadvantage of all AMOLED panels, but it is still characteristic of most of them. With this structure, the matrix contains an unequal number of red, green and blue subpixels (Samsung has half the number of blue ones, while LG has twice as many). The main motive for using PenTile is the desire to compensate for the disadvantages of blue LEDs. However, a side effect of this decision is a decrease in the clarity of the picture, especially noticeable in VR headsets.

Taking into account all the features of both types of matrices, it can be noted that IPS with high resolution is better if you are interested in VR and need maximum picture clarity. Indeed, in AMOLED, PenTile hinders the comfortable perception of virtual reality, and the PWM of the backlight so far neutralizes the instantaneous reaction speed. Also, IPS is better if you have to work more with light colors (web surfing, instant messengers).

AMOLED screens are the future, but the technology isn't perfect yet. However, you can safely buy a smartphone with an LED screen, especially if it is a flagship. Brightness, contrast, deep blacks and energy savings when displaying dark tones can overcome all the disadvantages of OLED.

Which technology is better - IPS or Amoled? Let's talk about the advantages and disadvantages of screens. How to make the right choice?

There was a time when the Samsung company loudly announced its Amoled technology, calling it almost the pinnacle in the production of matrixes. Initially, Amoled screens were used in TVs, then the technology was inherited by the brand's smartphones.

AMOLED displays are not liked for an unnatural picture, excessively high contrast, saturated colors.

At this moment, IPS screens with their clarity and natural picture appear on the market. Which is better - IPS or Amoled, and which display is right for you.

Advantages and disadvantages of IPS and AMOLED

Both technologies have a lot of them, this is a fact. Let's start with Amoled.

AMOLED – Active Matrix Organic Light Emitting Diode... The technology provides maximum screen brightness and high image contrast, excellent glare suppression in bright daylight / sunlight / lamp light. At the same time, the screen itself consumes little energy, since the pixels are activated only at the right time, while in IPS, all the pixels are constantly active when the screen is turned on.

Disadvantages of Amoled:

• The high cost of production, which significantly increases the price of a smartphone;
• High vulnerability to mechanical damage;
• Fading of colors is observed over time.

What is IPS? Here, too, everything is very ambiguous. In-Plane Switching technology was created as an ideological successor of TFT - a frankly outdated technology that does not give a juicy picture, good responsiveness, or wide viewing angles.

Having got rid of these shortcomings, IPS has become a real godsend. The picture is clear, dynamic, deep and rich. But most importantly, the colors have become truly realistic. Amoled, with its oversaturated color palette, loses a lot in this regard. Although, this is also a matter of taste. The picture is clear, the viewing angles are excellent - everything is gorgeous.

Disadvantages of IPS:

• Active energy consumption;
• Smartphones with IPS screens are slightly thicker than their Amoled counterparts;
• IPS requires more powerful backlighting;
• Slow matrix response (only the most picky users will be able to tell the difference);
• Pixel grid visibility.

AMOLED or IPS - which one to choose?

If you are faced with a choice - to buy a smartphone with an IPS or Amoled screen, start from how you will use it and what you generally expect from the screen. Want natural colors and generally good color reproduction? Choose IPS. Do you want the battery to last longer, and the picture to please with saturation and depth? Amoled for you.

At the same time, everyone should remember that you are not buying a TV, but a smartphone. The average user may not notice much difference between these technologies. And, perhaps, the best advice in choosing is to just look what you like best visually. Well, if you buy a phone for several years, then it's better to take it with an IPS matrix. The faded colors on Amoled are clearly not to your liking. Although, again, you may not even notice them.

Want to know what a "wow effect" is? Pick up at least one Samsung smartphone with an AMOLED display! And if this is "WOW!" you will not be able to escape, consider that the guys from Samsung did not work out their fees. So bright, so colorful, so attractive! Hands are drawn to scrolling sites, flipping through the gallery, climbing in applications and settings.

Is the almost-branded Samsung display that good, and what about IPS screens? They, of course, do not lead to wild delight at first glance, but the technology will be somewhat better than AMOLED.

Yes, familiarity with the latest Samsung gadgets is frantic. And if you have not yet turned into a zombie, and have not gone to the cashier to lay out hard-earned money for a bright and contrasting image of an armful of balloons on the main screen, all is not lost and you have something to talk about.

In fact, selling the brightness and contrast of AMOLED displays isn't all that perfect: the pretty wrapper hides a couple of significant annoyances.

What is AMOLED? AMOLED -Active Matrix Organic Light-Emitting Diode, i.e. active matrix on organic light-emitting diodes. The light emitters in AMOLED displays are organic light-emitting diodes, which are controlled by an active matrix of thin-film transistors (TFT).

Why AMOLED?

Firstly, AMOLEDs are incredibly contrasting screens, which IPS cannot boast of.

Secondly, thanks to the image transmission technology different from IPS, the AMOLED display can show absolutely black color. Why?

IPS screens are illuminated, as a rule, from all sides, and the pixels in AMOLED glow on their own, so the manufacturer was able to bring black to them to perfection: when displaying a picture on such screens, pixels transmitting black will not glow. In IPS screens, the whole picture is always highlighted, therefore it is impossible to achieve deep black transmission on them. The contrast of AMOLED displays is thus almost infinite.

The third advantage follows from the second advantage, albeit very controversial: AMOLED, due to the selective illumination of pixels, also claim to be selectively economical in energy consumption. In other words: on dark AMOLED scenes, the screen wastes nothing at all! But, on the other hand, when it comes to displaying a light picture, the efficiency of AMOLED technology can be called into question.

The fourth plus (s): the response time to touch of AMOLED displays is less than that of IPS. Those. the change of pictures on the screen should occur with lightning speed. In truth, AMOLEDs really work faster in this regard, but the speed difference is hardly perceptible.

By the way, in Samsung Galaxy S4 the notorious speed of reaction even became a problem: when changing the image (even when switching from menu to menu), “loops” from the previous picture are drawn across the screen. The manufacturer prefers not to answer the questions of what to do with this and how to continue to live. Looks like it's all about the new Super AMOLED technology. Not that it would be very disturbing, but it would be wrong to remain silent.

Fifth advantage: AMOLED is thinner, therefore, devices with such a display are lighter. The difference in the thickness of AMOLED and IPS is explained by the same backlight technology: the pixels in IPS still need to be backlit, and for the backlight you need a place in the case.

But, in fact, we are talking about a maximum of a hundred grams, therefore, if you do not have a fad on the superfine gadget, you should not consider the fifth point a significant advantage either.

The rich color gamut of AMOLED screens can be appreciated at least in the Samsung Galaxy S3 and Samsung Galaxy S4, as well as in the Galaxy Nexus.

What is IPS? IPS is a type of LCD monitor matrix, the name of which stands for In-Plane Switching. The technology is named so because of the way the crystals are placed in the panel. IPS is distinguished by the fact that the crystals are located in one plane parallel to the surface of the panel. This made it possible to obtain maximum viewing angles (up to 178 degrees).

Why IPS?

Firstly, despite the contrast of AMOLED, IPS screens reproduce colors much more accurately. If on AMOLED they can be twisted to completely unnatural shades, then IPS will give bright colors only when the real picture suggests it.

Natural colors on AMOLED can also be set, but not without difficulty and special access to the software settings. But in the presence of software AMOLED settings, the matrix can compete with any modern technology. Well, almost anyone.

Secondly, IPS screens give perfect white, which cannot be achieved on AMOLED. This is not a trifle as it might seem. Take, for example, the sad stories about the transfer of blue, yellow and pink shades of white by "amoles".

On the one hand, a custom software setting can put everything in place, but AMOLED will still not give a solid white AMOLED: if the color reproduction is still amenable to customization, then whitening the device's display will cost you a lot of effort.

Big plus number three: color preservation in IPS is possible even at a sharp viewing angle. Colors on high-quality IPS almost do not degrade, no matter how you look at the screen.

Who will say that all this is nit-picking, try to get a company of at least three people to watch a movie or photographs: the person sitting in the center will see the picture without distortion, but those sitting on the right and left of him will give off the colors yellow and blue, respectively.

IPS practically does not give angular distortion, and AMOLED, alas, does not indulge with such characteristics. Recall, for example, the Sony Xperia Z, the screen of which spoiled the impressions of, in principle, a good device: a faded screen with low contrast and poor viewing angles.

AMOLEDs are often sinned in that they give a shift in natural color rendition to the cold side. A non-standard sub-pixel layout, moreover, leads to the image leaving in different colors: depending on what angle you look at the screen, the picture may turn red or green.

Recall that most often one pixel is formed by three subpixels: red, green and blue (the so-called RGB layout).

AMOLED works in a different way. These screens use an imaging method in which the subpixels are arranged in a special way. For clarity, see the picture below. According to the standard, a pixel is formed by three RGB subpixels, and in AMOLED displays, the subpixels can be arranged as RG-BG, and not as RGB-RGB in the conventional version. This technology is called PenTile.

The photo below shows the standard RGB layout and the previous generation PenTile.

Subpixels of different colors can glow with different strengths, so on AMOLED the picture looks less detailed and clear (these flaws most often appear along the contours of the depicted objects).

There is no such looseness in IPS displays, respectively, IPS give better sharpness and detail. In fact, you don't need to have superpowers to notice the pixelation of a picture. Unlike IPS, the structure of the AMOLED matrix can be noticed, say, by any short-sighted user who decides to read a detective before going to bed. This is the fourth plus.

Again, because AMOLED illuminates each individual subpixel, there is a possibility of burning out these organic LEDs (example in the photo, see below). The warranty period of such a screen is at least 6 years, but after even a year of using the device, changes in brightness and color rendering can still be noticed.

IPS screens give a much higher maximum brightness. Hence: the readability of any image, accordingly, becomes better. AMOLED screens begin to "fade" in direct sunlight: the brightness of such a screen is not enough to illuminate the picture in the sun.

The display is one of the most important parts of a smartphone that we most often pay attention to when using it. True, not when buying, it's so easy to get lost in the variety of types of matrices and the listing of screen resolutions. That is why we will tell you about the types of displays and their resolutions. There are a huge variety of display matrices on the smartphone market - TFT, IPS, AMOLED and others. We will focus on the most important ones.

TFT is a display based on thin film transistors. This technology was invented back in 1959 and has already become covered with dust and cobwebs. TFT displays no longer meet all the necessary quality criteria for screens and are installed only in budget smartphones. Now TFT is inferior to IPS and OLED in color rendition and contrast.

However, they have one advantage - a high (1 ms) response time. Although the average user does not see the difference between 1 and 3 or 5-7 ms, that finally buries the technology.

The new Android Q is out. Perhaps this is the best OS from Google

Recently, Google released a beta version of Android Q for branded Pixel smartphones. The developers have improved the operating system, adding many useful innovations. We will tell you about all the main features

IPS (In-Plane Switching) is a technology that also evolved from LCD displays. In contrast to the same TFT (I hope you are not confused in terms yet?), IPS has a higher contrast and color rendering indices, as well as a wider viewing angle and reduced power consumption. However, IPS is criticized for oversaturation of color and insufficient saturation of the entire picture.

At the moment, IPS is perhaps the most popular technology for creating smartphones and tablets.

Retina is the marketing name for the above-described IPS technology invented by Apple. The Cupertino displays are characterized by a high pixel density (about 300 per inch), which makes them virtually indistinguishable on the matrix for the human eye.

In 2012, the company began introducing Retina displays to MacBook Pro laptops, and then new screens appeared in smartphones.

OLED and AMOLED

Organic light emitting diodes (Organic Light Emitting Diode) are widely used in the production of plasma panels, smartphones and tablets. Such displays are composed of thin sheets of electroluminescent material that produce their own light. The advantages of OLED over older technologies are lighter weight, no need for backlighting, increased viewing angle, brightness and contrast.

The main disadvantages of the technology are their high cost and short service life. Unfortunately, even in top-end flagships, OLED displays fade and fade after 2-3 years of use.

AMOLED (Active Matrix Organic Light-Emitting Diode) or Super AMOLED are the marketing names for LED panels by Samsung. In order not to boggle your head with unnecessary facts, just remember that these displays are more energy efficient and more expensive. The average eye won't tell the difference between AMOLED and OLED.

Display resolution

No matter how high-quality the display matrix is, a lot depends on its resolution. Resolution shows how many pixels are along the length and width of the display. The higher the resolution, the denser the pixels are on the sensor (PPI). We will tell you what resolutions are currently used in the mobile market.

HD (1280 x 720 pixels)

The basic resolution for smartphones, as a rule, is no longer lower than the indicator. All budget smartphones are equipped with HD displays, the PPI indicator in such devices fluctuates around 300 dpi. According to experts, the lower pixel density our eyes can already see clearly.

Full HD (1920 x 1080 pixels)

An indicator that is often common in sub-flags. For example, on smartphones with a 5-inch display, the PPI already hovers around 440 dpi. Full HD screens are equipped, for example, the flagships of 2016 OnePlus 3 and OnePlus 3T.

Quad HD (2560 x 1440 pixels)

Going further, with Quad HD, the pixel density on a 5.5-inch screen (a very popular option) rises to 538 dpi. For Full HD, for example, this figure will be only 400 dpi. In order not to get confused, you need to remember that Quad HD is often called 2K.

Ultra HD (4096 x 3840 pixels)

Highest display resolution available in the smartphone market today. Ultra HD resolution is often referred to as 4K. For example, the Sony Xperia Z5 Premium has a 5.5-inch display at 806 ppi - nearly three times that of HD panels.

Which display is better?

It is difficult to answer, because everyone chooses a smartphone based on their requirements and tasks. Objectively speaking, in most cases a flagship with a Super AMOLED display and a 2K resolution will display a picture much better than smartphones with an IPS matrix and Full HD resolution. However, there are nuances.

For example, there is no point in overpaying for Super AMOLED if there is a more affordable smartphone with an OLED display nearby - you will not notice the difference, but you will lose money in money. Or it's crazy to take a smartphone with an IPS display and HD resolution, and then wait for it to display realistic photos taken with a professional camera. In any case, if you are serious about buying a smartphone and you have the opportunity to touch it in your hands before buying, then do so. And, best of all, take two or three applicants for a purchase in your hands, turn them on and compare them head to head.

Two things prompted me to create this article: numerous speculations by marketers and specialized journalists on the topic of screens; and a bunch of absolutely identical comment threads under smartphone reviews with absolutely identical discussions about which matrices are better. Usually, the hottest part is under the reviews of Chinese phones with OLED screens. I'm tired of fighting windmills, communicating with each reader individually, in this article I decided to dot the i's and dispel numerous myths about modern screens, looking ahead I will say that the emphasis will be on the opposition of IPS and AMOLED matrices. Most likely, most of you will not see anything new in what you have written, you will not receive sacred knowledge here, as well as tearing off the veils. I will talk about the obvious things that neither bloggers nor journalists want to talk about. The guide is designed for adequate thinking people, convinced fanatics can go about their business.

Definition of the term "screen"

Before getting to the point, you need to define the term screen and clarify its functionality. Wikipedia tells us that a screen or display is an electronic device designed to display information visually. If we try to give a less concise and more modern definition of a screen in terms of functional purpose and with an emphasis on consumer properties, then it will turn out something like this: the screen is a device whose task is to display all kinds of content and the user interface of operating systems and applications as accurately and in detail as possible. how the authors intended them. Physical resolution is responsible for the “maximum detail”, otherwise: the number of the smallest screen elements (picture's elements) or just pixels (pixels), the higher the resolution, the better, ideally it should be infinitely large. For “as accurate as possible” such parameters as: color accuracy and contrast or the ratio of the lightest and darkest point on the screen are responsible. Secondary parameters that do not directly affect either the accuracy or the detail of the information display, but affect the consumer properties of the screen, include: maximum brightness, picture distortion when the gaze deviates from the perpendicular, reflection coefficient, picture refresh rate, response time, energy efficiency and some others ... Standing apart is such a parameter as color gamut - the most important parameter for professional monitors and practically meaningless for devices intended for content consumption. But it is the color gamut that has been the subject of a lot of speculation on the part of mobile gadget manufacturers in recent years. Let's clear up this muddy topic before moving on.

What is color gamut and why is it the subject of much speculation

You need to start with the fact that any image when captured and saved to the memory of a photo or video camera is encoded. Artificially created pictures and clips, as well as parts of the graphical user interface of operating systems and applications, are encoded in a similar way from the beginning. In both cases, color information is represented using a color model - a special mathematical tool for describing color using numbers or, to be precise, coordinates. The most common is the three-dimensional RGB model, in which each color is described by a set of three coordinates responsible for one of the colors: red, green and blue, the displayed hue depends on the brightness ratio of each component. Modern screens are capable of displaying only a part of the spectrum of colors and shades visible to humans, the color gamut literally means how large this “part” is. Due to this limitation, a person is forced to create standards for representing the color spectrum based on the capabilities of existing screens. So in 1996, to unify the use of the RGB model in monitors and printing, HP and Microsoft developed the sRGB standard, which used the primary colors described by the BT.709 standard that was widespread on television and gamma correction designed for monitors with a cathode ray tube. It is important to understand that such unification allows, albeit with some reservations, to ensure that the creator and the consumer of content on their screens will see approximately the same thing. Subsequently, the sRGB standard has become widespread in all areas of content production, including in the field of creating Internet sites. Of course, there are other standards for representing the color spectrum, for example, Adobe RGB, the color gamut of which is much wider, but today the vast majority of content is encoded in accordance with sRGB.

What happens if sRGB content is viewed on a wider gamut screen without adaptation? The sRGB space coordinates will be transferred to the color space coordinate system of such a screen, as a result of which the colors will appear more saturated than they actually are, in some cases the shades will be distorted so much that orange turns red, lime green, and cyan blue. Conversely, if content with a wider color gamut is viewed on an sRGB screen, shifting the coordinates will cause colors to appear less saturated than they should be.

We all know that the screens of most modern flagship smartphones have an extended color gamut relative to sRGB, how does this affect their consumer properties? If this is an android smartphone or tablet, then there are three options. At best, the shell settings will have preset color profiles, among which there is one that brings the space to the sRGB standard, for example MIUI or the shell from Samsung. But, even in this case, the application of profiles “on the fly” is not possible, and the user will have to choose between extended color gamut and correct color reproduction. The second option is when the system does not have built-in profiles, but in the developer settings you can activate the sRGB mode, for example, this can be done on Google Pixel and OnePlus 3T smartphones. Unfortunately, the operating system's graphical interface becomes faded when sRGB is activated, as it is encoded according to the color gamut of their screens. In the third worst case, the user will not find any profiles in the system and will not receive any choice, respectively, he will only have to enjoy oversaturated colors. But in personal computers on Windows and MacOS, there is no such problem, since both systems not only support color profiles, but can also “on the fly” convert colors from one space to another, that is, regardless of what content and on what screen will be displayed, the user, with some reservations, will see the colors as the author intended. IOS has a similar color profile management system. Manufacturers, whether for the sake of beautiful numbers on the specifications page, or just for the sake of it, continue to install screens with extended color gamut in the flagship models of IPS and OLED, despite the fact that there is no need for this, since 99% of the content complies with the sRGB standard and the situation is unlikely to change radically in the near future. The tasks that such screens can perform in devices created for the consumption of content simply do not exist. All of this would make some sense if Google added color profile management to Android, as Apple did, but at least in 2017 we won't see that. The irony is that the problem was created from scratch, and no one is in a hurry to solve it.

Liquid crystal screen: working principle; Advantages and disadvantages

Twenty years ago, screens based on a cathode-ray tube were installed in most monitors and televisions, soon they were replaced by liquid crystal screens or LCD (liquid crystal display), which over time received several branches of development and today there are three technologies for the production of liquid crystal matrices screens: TN, MVA and IPS, the latter, due to a successful combination of advantages and disadvantages, has become dominant in the segment of mobile technology. The principle of LCD operation is simple, depending on the production technology, some details may vary, but a typical matrix includes a backlight lamp and six other layers. First behind the lamp is a vertical filter that polarizes the light accordingly. It is followed by two layers of electrodes with a layer of liquid crystals located between them, the voltage applied to the electrodes orientates the crystals and they refract the light so that it passes or does not pass through the next layer - a horizontal polarizing filter. The last is the color filter - red, green or blue. Liquid crystal screens are lighter, more compact and more energy efficient than their predecessors, but they also have a number of serious drawbacks, in particular, low contrast and black depth, even limited color gamut potential, which depends on the imperfection of backlight lamps. In addition, brightness and contrast performance may deteriorate if the screen is not viewed at a right angle.

OLED Screen: Advantages, Disadvantages, PWM, Pentile

Relatively recently, LCD has a serious competitor - these are active matrix OLED screens or AMOLEDs. Such screens are fundamentally different from LCDs in that the light source in them is not a backlight, but each subpixel separately, which gives AMOLED many advantages over liquid crystal screens, the main ones of which are: almost infinite contrast; less power consumption when displaying images with a predominance of dark tones; potentially wider color gamut; and smaller dimensions. The first AMOLED screens, in addition to advantages, had significant disadvantages, including: inaccurate color reproduction; fast burning out of LEDs; high power consumption when displaying images with a predominance of light tones; flickering due to pulse width modulation; and most importantly the high cost of production. Over time, most of the shortcomings were overcome or minimized, except for PWM, which is the Achilles heel of technology to this day. Pulse Width Modulation or PWM is one way to adjust the brightness of LEDs, the side effect of which is that the screen flickers at some frequency. Most people are not susceptible to this kind of flickering, but for some users, PWM can cause rapid eye fatigue and even headaches. It is important to note that the flickering effect is completely absent at brightness values ​​close to maximum and begins to appear at a brightness level of 80% and below.

It is impossible to ignore the topic with the organization of subpixels in OLED screens, the fact is that in most AMOLED matrices, subpixels are arranged according to the RGBG scheme, when a pixel does not consist of three subpixels as in a typical LCD screen, but of four: red, blue and two green, this scheme is also called Pentile. The manufacturer (Samsung) considers the physical resolution of such screens to be exactly two times less by the number of green subpixels, red and blue subpixels in the matrix. Obviously, you need at least three full subpixels to get a hue. Thus, the effective resolution of such screens is not equal to the nominal resolution specified in the official specification. For example, for a QHD screen, the nominal resolution is 2560 * 1440 pixels, the resolution based on the number of red and blue subpixels will be approximately 1811 * 1018:

The effective resolution of such a matrix, taking into account the clever interpolation algorithms embedded in the screen controller, is somewhere between 1811 * 1018 and 2560 * 1440, we can assume that it corresponds to the FullHD resolution in RGB matrices. It may very well be that it is for such a match that Samsung has chosen QHD resolution for its flagship smartphones for many years in a row.

A detailed comparison of IPS and AMOLED on the example of the screens of smartphones iPhone 7 and Galaxy S8

Now, after we have learned all about the characteristics of screens and about the features of different types of matrices, we can move on to the main question: which technology is better? I am sure that it is correct to try to answer this question by comparing the best AMOLED and IPS matrices available today, namely the screens of the Samsung Galaxy S8 and Apple iPhone 7 smartphones. Since I have not yet acquired test equipment, I will analyze the test results taken from an authoritative resource. Let's start with the resolution, the Galaxy S8 screen has 2960 * 1440 pixels, the guaranteed effective resolution will be 2094 * 1018, and the guaranteed effective pixel density is 403 per inch. The iPhone 7 Plus has a nominal effective resolution of 1920 * 1080, and an effective pixel density of 401 per inch. There is an obvious preponderance in favor of the screen from the Korean vendor. The resolution of both screens is enough for everyday use and not enough for comfortable operation with virtual reality helmets. Moving on to accuracy, the Galaxy S8's contrast ratio is nearly infinite. The iPhone 7 has a declared contrast ratio of 1400: 1, the actual one is slightly higher - 1700: 1, this contrast is more than enough for comfortable viewing of content. It turns out that the screen of the Galaxy S8 is ahead in this parameter as well. In terms of color accuracy, both smartphones showed virtually the same results, color errors in the Galaxy S8 and iPhone 7 can be safely ignored. You can see the most important secondary characteristics in my opinion below:

As for the color gamut, then the iPhone 7 is ahead, since it can display the colors of the DCI-P3 space or 126% of the sRGB field, while the user does not need to sacrifice color rendition, the content is displayed based on the color profile embedded in it. The Galaxy S8's screen has an even wider color gamut - about 142% of the sRGB field, but does not have color profile management, driving the user into a corner, that is, in Basic mode, which corresponds to 100% of the sRGB field.

So what's the bottom line? If we consider screen technologies in isolation from the final product, then AMOLED today surpasses IPS in almost everything, although it still has problems with PWM and high power consumption. There is no doubt that OLEDs are the future. Unfortunately, due to the limitations of Android, their potential has not yet been fully revealed. When comparing ready-made solutions in the face of Galaxy S8 and iPhone 7, it is obvious that the latter is slightly superior due to the honest DCI-P3 and other reference parameters. I want to warn you against projecting the results of the above comparison on absolutely all IPS and AMOLED screens. There are a lot of good, average and bad matrices on the market, and each case needs to be dealt with separately. In this we will be helped by Internet publications focused on technical detail and reliability, to such publications I would include the already mentioned anandtech.com and some other sites from Russian-language sites - ixbt.com.

Perhaps you shouldn't take the consumer properties of screens too seriously, because objective information is almost always superimposed on the factor of subjective perception. For example, in Southeast Asia there are a lot of people who like unnatural oversaturated colors, in our country there are also a lot of such people. On the other hand, broadcasting information poured into the ears of marketers in numerous discussions under reviews on YouTube is at least strange. In the end, I'll be Cap and give a couple of banal advice: don't stop thinking and be critical of any information you get from brand representatives and the media, be able to analyze data and check facts, or just read resources and watch bloggers you can trust.