Comparison Dell U2518D 25 " black vs Dell U2515H 25 " black

The technology by which the monitor matrix is made.

— TN+film. The oldest and most common technology for manufacturing matrices. The original TN (Twisted Nematic) monitors have a low response time and low cost, but the image quality is average. So, the colour quality is not high, and the perfect black colour cannot be reproduced at all. In addition, the original TN technology provides relatively small viewing angles. To correct this situation, a special film is applied to the surface of the matrix. These matrices received the name "TN + film". Monitors with such a matrix are widespread and inexpensive. They are well suited for undemanding users both at home and in the office, and gamers will appreciate the fast response time.

— *VA(Vertical Alignment, options: MVA, PVA, Super MVA, Super PVA). A kind of transitional option between expensive and high-quality IPS and low-cost TN. Provide sufficiently high-quality colour reproduction, including black colour, viewing angles can reach 178°. The main disadvantage of VA matrices is the significant response time (especially for MVA monitors), due to which such monitors are relatively poorly suited for watching videos and dynamic games. This shortcoming is gradually being eliminated, and the latest models of VA monitors are approaching TN + film in respo...nse time.

— IPS. Initially, IPS technology was created for high-end monitors (in particular, "designer"), the key parameters for which were the quality of colour reproduction and a wide colour gamut. With all these advantages, the original IPS matrices also had a number of serious drawbacks — first of all, low response speed and impressive cost. Thus, many modifications of the IPS technology have been developed, designed to compensate for these shortcomings to one degree or another.

— OLED. Monitors with screens using organic light emitting diodes — OLED. Such LEDs can be used both to illuminate a traditional matrix, and as elements from which a screen is built. In the first case, the advantages of OLED over traditional LED backlighting are compactness, extremely low power consumption, backlight uniformity, as well as excellent brightness and contrast ratios. And in matrices, consisting entirely of OLED, these advantages are even more pronounced. The main disadvantages of OLED monitors are the high price (which, however, is constantly decreasing as the technology develops and improves), as well as the susceptibility of organic pixels to burn-in when broadcasting static images for a long time or pictures with static elements (toolbar, clock, etc.).

— QLED. Monitors built using quantum dot technology (QLED). This technology can be used in matrices of various types. It involves replacing a set of several colour filters used in classic matrices with a special thin-film coating based on nanoparticles, and traditional white LEDs with blue ones. This allows you to achieve higher brightness, colour saturation and colour quality at the same time as reducing the thickness and reducing power consumption. In addition, QLED is well suited for creating curved screens. The flip side of these benefits is the high price.

— QD-OLED. A kind of hybrid version of matrices that combine “quantum dots” (Quantum Dot) and organic light-emitting diodes (OLED) in one bottle. The technology takes the best from QLED and OLED: it is based on blue LEDs, self-luminous pixels (instead of external backlighting) and “quantum dots”, which play the role of color filters, but at the same time practically do not attenuate the light (unlike traditional filters) . Thanks to the use of a number of advanced solutions, the creators managed to achieve very impressive characteristics, significantly superior to many other OLED matrices. Among them are high peak brightness from 1000 nits (cd/m²), excellent contrast and black depth, as well as an expanded color gamut (over 120% of the DCI P3 gamut). Such matrices are found mainly in expensive advanced monitors with a large screen diagonal.

— AHVA. A type of matrix created by AU Optronics (a joint venture between Acer and BenQ) as a solution similar to modern IPS. Among the key advantages of this option over analogues is the almost complete absence of colour distortions at all viewing angles.

– PLS (Plane to Line Switching). This type of matrix was developed by Samsung engineers. It is based on the familiar IPS technology. According to some parameters, namely: the brightness and contrast of PLS exceeds IPS by 10%. The main goal of creating a new type of screens was to reduce the cost of the matrix, according to the developer, the production cost was reduced by 15%, which will positively affect the final price of monitors in comparison with IPS counterparts.

— IGZO. Technology introduced by Sharp in 2012. The key difference between IGZO and classic LCD matrices is that for the active layer (responsible for creating the image) it uses not amorphous silicon, but a semiconductor material based on indium gallium oxide and zinc oxide. This makes it possible to create screens with extremely fast response times and high pixel densities, and the technology is considered well suited for ultra-high resolution screens. With all this, the colour rendering characteristics allow the use of IGZO monitors even in the professional field, and the power consumption is very low. The main disadvantage of this option is the high cost.

— UV2A. An LCD display technology developed by Sharp and introduced in 2009. One of the key features of UV2A matrices is that they are based on liquid crystals that are sensitive to ultraviolet light. And it is UV radiation that is used as a control signal — it ensures that the crystals turn in the right direction to form an image. The technical features of such systems are such that the position of individual crystals can be controlled with extremely high accuracy — up to several picometers (with the size of the crystals themselves about 2 nm). According to the manufacturer, this provides two key benefits: no backlight "leakage" and improved light transmission with "open" crystals. The first allows you to achieve very deep and rich blacks, the second provides excellent brightness with low power consumption, and together these two features make it possible to create screens with a very high static contrast ratio — up to 5000: 1. At the same time, we note that the actual contrast characteristics in UV2A monitors can be noticeably more modest — it all depends on the features of a particular matrix and the characteristics that the manufacturer was able or considered necessary to provide.

— Mini LED IPS. A variation on the theme of the familiar IPS-matrix, which is illuminated by an array of reduced LEDs. The small caliber of individual light sources (of the order of 100-200 microns) makes it possible to form a much larger number of zones of controlled local dimming of the screen. Together, this delivers improved brightness, contrast, colour saturation, and black depth, and raises the bar for High Dynamic Range (HDR) technology.

— Mini LED VA. A variety of VA-matrices with a Mini LED backlight system. It consists of many tiny LEDs, which, due to their number, form many times more local screen dimming zones than standard canvases. As a result, Mini LED VA panels boast improved colour reproduction, impressive black depth, and multiple performance improvements in HDR content.

— Mini LED QLED. Behind the plane of the QLED panel in monitors with a Mini LED backlight system are thousands of miniature LEDs no larger than 200 microns in size, which divide the screen into a great many zones with controlled local dimming. They are individually dimmable, allowing full display of HDR content with bright light and deepest black levels.

Modern monitors can use displays with both glossy and matte screen surfaces. A matte surface is in some cases more preferable due to the fact that on a glossy screen, when exposed to bright light, noticeable glare appears, sometimes interfering with viewing. On the other hand, glossy screens offer better picture quality, higher brightness, and richer colours.
Due to the development of technology, monitors with a special anti-glare coating have appeared on the market, which, while maintaining all the advantages of a glossy screen, creates significantly less visible glare in bright ambient light.

The size of one dot (pixel) on a monitor screen. This parameter is related to the maximum resolution of the monitor and its diagonal size — the higher the resolution, the smaller the pixel size (with the same diagonal) and vice versa, the larger the diagonal, the larger the size of one pixel (with the same resolution). The smaller the size of one pixel, the clearer the image will be displayed by the monitor, the less grainy it will be noticeable, which is especially important on large monitors. On the other hand, a small pixel size creates discomfort when working with fine details and text — this mainly applies to monitors with a small diagonal.

The time each individual pixel on the monitor takes to switch from one state to another. The lower the response time, the faster the matrix responds to the control signal, resulting in less delay and better image quality in dynamic scenes.

Note that in this case, the gray-to-gray method is used (the time it takes to switch from 10% gray to 90% gray). Pay attention to this parameter if the monitor is specifically purchased for fast-paced games, movie watching, or other applications involving quick screen movements. However, there’s no need to chase the fastest models. It’s not often possible to discern the difference between 1 ms and 5 ms. For most scenarios, monitors with a 4 ms response time will suffice. In any case, it’s best to rely on live impressions for a true comparison.

The maximum frame rate supported by the monitor at the recommended (maximum) resolution.

The higher the frame rate, the smoother the movement on the screen will look, the less noticeable jerks and blurring will be on it. Of course, the actual image quality also depends on the video signal, but for normal viewing of video at a high frame rate, the monitor must also support it.

When choosing this option, keep in mind that at lower resolutions than the maximum, the supported frame rate may be higher. For example, a model with a 1920x1080 matrix and a claimed frame rate of 60 Hz at a reduced resolution can give 75 Hz; but the 75Hz frame rate is only listed in the specs if it is supported at the monitor's native (maximum) resolution.

Also note that a high frame rate is especially important for gaming models (see "Type"). In most of them, this figure is 120 Hz and higher; monitors with a frequency of 144 Hz are considered the best option in terms of price and quality, however, there are also higher values — 165 Hz and 240 Hz. And monitors at 100 Hz can be both inexpensive gaming models and advanced home ones.

You can evaluate all the frame rates at which this monitor is capable of operating by the ver...tical frequency claimed in the specifications (see below).

Dynamic contrast provided by the monitor screen.

Dynamic contrast refers to the difference between the brightest white at maximum backlight intensity and the deepest black at minimum backlight. In this way, this indicator differs from static contrast, which is indicated with a constant backlight level (see above). Dynamic contrast ratio can be expressed in very impressive numbers (in some models — more than 100,000,000: 1). However, in fact, these figures are poorly correlated with what the viewer sees: it is almost impossible to achieve such a difference within one frame. Therefore, dynamic contrast is most often more of an advertising than a practically significant indicator, it is often indicated precisely in order to impress an inexperienced buyer. At the same time, we note that there are "smart" backlight technologies that allow you to change its brightness in certain areas of the screen and achieve a higher contrast in one frame than the claimed static one; these technologies are found mostly in premium monitors.

This technology is designed to expand the range of brightness reproduced by the monitor; Simply put, an HDR model will display brighter whites and darker blacks than a "regular" display. In fact, this means a significant improvement in colour quality. On the one hand, HDR provides a very "live" image, close to what the human eye sees, with an abundance of shades and tones that a normal screen cannot convey; on the other hand, this technology allows to achieve very bright and rich colours.

Modern HDR monitors may use the DisplayHDR designation. This standard takes into account a number of parameters that determine the overall quality of HDR performance: brightness, colour gamut, colour depth, etc. Based on the results of measurements, the monitor is assigned one of the following markings: DisplayHDR 400 means relatively modest HDR capabilities, DisplayHDR 600 is average, DisplayHDR 1000 is above average, DisplayHDR 1400 is advanced. At the same time, the absence of a DisplayHDR label in itself does not mean anything: it’s just that not every HDR monitor is tested according to this standard.

Note that for the full use of HDR, you need not only the appropriate monitor, but also content (movies, television, etc.) originally created in HDR. In addition, there are several different HDR techn...ologies that are not compatible with each other. Therefore, when buying a monitor with this function, it is highly desirable to clarify which version it supports.

— VGA. A connector designed for transmitting analog video signals back in the era of CRT monitors (especially for them). Today it is considered obsolete and is gradually falling out of use - in particular, due to low bandwidth, which does not allow full work with HD content, as well as double signal conversion when using VGA in LCD monitors (which can become a potential source of interference) .

— DVI. A connector for video signal transmission, designed specifically for LCD devices, including monitors. Although the abbreviation DVI originally stands for “digital video interface,” this interface also allows analog data transmission. Actually, there are three main types of DVI: analog, combined and digital. The first type in modern computer technology has almost gone out of use (this function is actually performed by the VGA connector), and a purely digital connector - DVI-D - is indicated separately in our catalog (see below). Therefore, if the monitor’s specifications indicate “just DVI”, most likely we are talking about a combined DVI-I connector. In terms of the characteristics of the analog video signal, it is similar to the VGA described above (and is even compatible with it through a simple adapter); in terms of digital capabilities, it is DVI-D (single-channel, not Dual Link). However, due to the spread of purely digital standards, DVI-I is becoming less and less...common.

— DVI-D. A variation of the DVI interface described above that supports exclusively digital video signal format. The standard (Single Link) DVI-D interface allows you to transmit video in resolutions up to 1920x1080 at a frame rate of 75 Hz or 1920x1200 at a frame rate of 60 Hz, which is already enough to work with modern resolutions up to Full HD inclusive. In addition, there is a dual-channel (Dual Link) version of this connector, which has increased bandwidth and allows you to work with resolutions up to 2560x1600 (at 60 Hz; or 2048x1536 at 75 Hz). Accordingly, the specific DVI-D type depends on the monitor resolution. In this case, a single-channel screen can be connected to a dual-channel video card, but not vice versa. Also note that the situation with connectors is similar: Single Link and Dual Link ports are slightly different in design, and a single-channel cable is compatible with dual-channel input/output, but, again, not vice versa.

— DisplayPort. An interface originally created for video transmission (however, it can also be used for audio signals - in this DisplayPort is similar to HDMI). Found in many modern monitor models. Note that monitors with DisplayPort inputs are also compatible with Thunderbolt outputs (via an adapter).

The specific capabilities of this connector depend on its version. Modern monitors have the following options:

• v.1.2. The earliest version commonly used in our time, released in 2010. It was there that features such as 3D support and the ability to connect multiple screens in a daisy chain were first introduced. Version 1.2 allows you to transmit 5K video at a frame rate of 30 fps; working with higher resolutions (up to 8K) is also possible, but with certain restrictions.
• v.1.3. DisplayPort version released in 2014. It has one and a half times more bandwidth than v.1.2, and allows you to transmit 8K video at 30 fps, 5K at 60 fps and 4K at 120 fps. In addition, this version has a Dual-mode function, which allows you to connect to HDMI and DVI outputs through simple passive adapters.
• v 1.4. In this version, the maximum frame rate when working with one screen has increased to 120 fps for the 8K standard and to 240 fps for the 4K and 5K standards (data is supposed to be transmitted with compression using DSC - Display Stream Compression technology). Other features include compatibility with HDR10 and the ability to simultaneously transmit up to 32 channels of audio.
• v2.1. 2022 version using the same physical layer specification as USB4. The interface bandwidth has been doubled compared to v 1.4 (up to 80 Gbit/s, of which 77.37 Gbit/s is available for data transfer). At the same time, it supports connecting displays with resolutions up to 16K at 60 fps, 8K at 120 fps, 4K at 240 Hz and 2K at 480 Hz (without the additional use of DSC - Display Stream Compression technology). DP40 (40 Gbps) cables can now be longer than two meters, while DP80 (80 Gbps) cables can be more than one meter long.

— Mini Display Port. A smaller version of the DisplayPort described above, used primarily in laptops; especially popular in Apple laptops. Recently, there has been a trend towards replacing the Mini Display Port with a universal Thunderbolt interface; however, this interface operates through the same connector and provides the same capabilities. In other words, monitors can be connected to Thunderbolt (versions 1 and 2) via a standard miniDisplayPort cable, without using adapters (for v3 you will still need an adapter).

— HDMI. The HDMI interface was originally designed to transmit high-definition video and multi-channel digital audio over a single cable. This is the most popular of modern interfaces for this purpose; HDMI outputs are practically mandatory both for computer video cards and for media centers, DVD/Blu-ray players and other similar equipment.

The presence of several outputs of this type in the monitor allows you to keep it connected simultaneously to several signal sources - for example, a computer and a satellite TV tuner. This way you can switch between sources through software settings without fiddling with reconnecting cables, and also use the PBP function.

At the same time, the port itself has different versions, and the most common in our time are as follows:

• - v.1.4. The earliest version actively used in our time; appeared in 2009. Supports resolutions up to 4096x2160 at 24 fps, and in the Full HD standard (1920x1080) the frame rate can reach 120 fps; 3D video transmission is also possible.
• - v.2.0. Version introduced in 2013 as a major update to the HDMI standard. Supports 4K video with frame rates up to 60 fps (due to which it is also known as HDMI UHD), as well as up to 32 channels of audio and up to 4 audio streams simultaneously. Also in this version there is support for ultra-wide format 21:9.
• - v.2.1. Quite a significant update compared to version 2.0, introduced at the end of 2017. A further increase in throughput made it possible to provide support for resolutions up to 8K at 120 fps inclusive. Improvements have also been made regarding working with HDR. Note that to use all the features of HDMI v 2.1 you need HDMI Ultra High Speed cables, although basic functions are available with regular cables.

— USB C (DisplayPort AltMode). Another type of USB interface used to work with video signals. It has a small size (not much larger than a microUSB) and a reversible design that allows you to connect the plug to either side - this makes Type C more convenient than previous standards. At the same time, we note that such a monitor may initially be designed for connection to a USB C output (at least, such an adapter cable may be supplied in the kit); it would not hurt to clarify this point separately.

— Thunderbolt interface. Thunderbolt is a data transfer protocol (used in Apple devices), the throughput of which reaches 40 Gbps. The connector itself, as well as the speed, depend on the version: Thunderbolt v1 and v2 use miniDisplayPort (see above), monitors with Thunderbolt inputs are not necessarily compatible with the original miniDisplayPort outputs - it wouldn’t hurt to check this compatibility separately. And Thunderbolt v3 is based on the USB C connector (see above).

— Mini-Jack input (3.5 mm). Audio input with standard 3.5mm mini-jack. Usually, it looks like a socket into which a mini-jack plug is connected from a signal source. The signal itself from such an input can be fed either to the monitor's built-in speakers or to the audio output (see below for both).

— Mini-Jack output (3.5 mm). Analogue audio output using a standard 3.5mm mini-jack. Usually it is universal, it can be used both for connecting headphones and as a line output for computer speakers or other active acoustics. The presence of an audio jack on the monitor is convenient because such a port is usually closer to the user than the audio card outputs, and connecting headphones or speakers directly to the monitor is easier than pulling a wire to the system unit.

-LAN. Standard connector for wired connection to computer networks. The presence of such an input in most cases turns the monitor into a network device: any network user with the appropriate access rights can display an image on it. Another use case for LAN is a direct connection to another device. For example, in this way you can connect a laptop with a LAN output without disconnecting the monitor from the PC (to which it can be connected, for example, via the DVI interface). And some especially advanced models have embedded software tools that allow using t...he local network to view the contents of devices connected to this network, and even use some web services directly from the monitor, without using a computer as such.

— Composite. One of the simplest and most common analogue audio/video inputs. Like component, it uses three wires and in its standard form consists of three RCA connectors; in some monitors, both interfaces can even be implemented through one set of connectors, switched to "component" or "composite" modes in the settings. The peculiarity of this standard is that it allows you to transmit both picture and sound: one of the wires is used for the analogue video signal, and the remaining two are responsible for the left and right stereo channels. However the composite interface is considered outdated: due to video transmission over a single cable, the quality and noise immunity of the picture are low, and there is no talk of HD resolutions at all. On the other hand, such outputs are still quite popular in video technology — both modern and frankly outdated (like VHS VCRs). And the ability to connect both video and sound at once is very convenient. However, if the monitor has neither audio outputs nor built-in speakers, it usually provides a stripped-down version of this connector — "composite video", with one RCA jack.

— Coaxial (S/P-DIF). An electrical version of the S / P-DIF interface: through one coaxial RCA connector (tulip), sound is transmitted digitally, including multichannel. This connector is found mainly among large-format plasma and LCD panels (see "Type"), where it plays the role of an output for connecting external audio systems — primarily home theaters and other advanced multi-channel acoustic sets.

— Linear. The line interface is a standard audio interface for transmitting an audio signal in analogue format. In general, the most popular way to use this connector is to output sound to active speakers and/or an external amplifier. However, monitors can have both outputs and inputs of this type. In this sense, the line interface is similar to the 3.5 mm jack described above; moreover, in some models, the mini-Jack plays the role of a linear connector.

— Optical. Another type of S / P-DIF connector, in addition to the coaxial output described above. It is used for the same purpose — to output multi-channel sound to external acoustics — however, it uses not an electrical, but an optical (light-guide) cable, so that such a connection is absolutely not subject to electrical interference. On the other hand, optical fibre requires careful handling, as it can crack from bending or strong pressure. It is also worth noting that, unlike coaxial, the optical output is found in both large and relatively small monitors.

— COM port (RS-232). Universal digital interface for transferring various data. In monitors, it usually plays an auxiliary role: it allows you to control the screen settings from a connected computer or other device, and in models with touch screens it can also be used to transfer data from the sensor to the computer. It is much less common than USB, it is practically not used in laptops, but it has the advantage of a maximum cable length — 15 m versus 5 m.