tft display vs tn quotation

IPS (In-Plane Switching) lcd is still a type of TFT LCD, IPS TFT is also called SFT LCD (supper fine tft ),different to regular tft in TN (Twisted Nematic) mode, theIPS LCD liquid crystal elements inside the tft lcd cell, they are arrayed in plane inside the lcd cell when power off, so the light can not transmit it via theIPS lcdwhen power off, When power on, the liquid crystal elements inside the IPS tft would switch in a small angle, then the light would go through the IPS lcd display, then the display on since light go through the IPS display, the switching angle is related to the input power, the switch angle is related to the input power value of IPS LCD, the more switch angle, the more light would transmit the IPS LCD, we call it negative display mode.

The regular tft lcd, it is a-si TN (Twisted Nematic) tft lcd, its liquid crystal elements are arrayed in vertical type, the light could transmit the regularTFT LCDwhen power off. When power on, the liquid crystal twist in some angle, then it block the light transmit the tft lcd, then make the display elements display on by this way, the liquid crystal twist angle is also related to the input power, the more twist angle, the more light would be blocked by the tft lcd, it is tft lcd working mode.

A TFT lcd display is vivid and colorful than a common monochrome lcd display. TFT refreshes more quickly response than a monochrome LCD display and shows motion more smoothly. TFT displays use more electricity in driving than monochrome LCD screens, so they not only cost more in the first place, but they are also more expensive to drive tft lcd screen.The two most common types of TFT LCDs are IPS and TN displays.

TFT displays are full color LCDs providing bright, vivid colors with the ability to show quick animations, complex graphics, and custom fonts with different touchscreen options. Available in industry standard sizes and resolutions. These displays come as standard, premium MVA, sunlight readable, or IPS display types with a variety of interface options including HDMI, SPI and LVDS. Our line of TFT modules include a custom PCB that support HDMI interface, audio support or HMI solutions with on-board FTDI Embedded Video Engine (EVE2).

IPS, also known as In-Plane Switching, is a type of monitor display and screen technology that uses a voltage to control the alignment of liquid crystals, similar to TN technology. However, IPS displays use a different crystal orientation where the crystals are parallel to the glass substrates, hence the term ‘in-plane’. Rather than ‘twisting’ the crystals to modify the amount of light let through, IPS crystals are essentially rotated, which has a range of benefits. IPS displays offer the best color reproduction as well as the widest viewing angles compared to other LCD technologies.

While TN LCD’s support high refresh rates with low response times, they do come with sub-optimal viewing angles, and slightly diminished color reproduction. IPS panels address these downfalls with 80 degree viewing angles that eliminate color inversion and contrast diminishment. IPS technology is ideal for a wide array of applications such as medical, industrial, HVAC, Pool/Spa due to the ability to use the displays in both landscape and portrait mode while maintaining uniform viewing angles. This also allows for displays to be seen from different angles and heights, ideal for jacuzzi controls and thermostats that tend to require consideration of dynamic user parameters.

A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technologyactive matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968. In 1971, Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated a 2-by-18 matrix display driven by a hybrid circuit using the dynamic scattering mode of LCDs.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).active-matrix liquid-crystal display (AM LCD) using CdSe TFTs in 1974, and then Brody coined the term "active matrix" in 1975.high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a voltage can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large display, because it would have a large number of (color) picture elements (pixels), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to transistor switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display"s image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Modern, high end consumer products have developed methods to overcome the technology"s shortcomings, such as RTC (Response Time Compensation / Overdrive) technologies. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology.

Most TN panels can represent colors using only six bits per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called Frame Rate Control (FRC), which cycles between different shades with each new frame to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.gamut (often referred to as a percentage of the NTSC 1953 color gamut) are also due to backlighting technology. It is not uncommon for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED phosphor formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference quite perceivable by the human eye.

In-plane switching was developed by Hitachi Ltd. in 1996 to improve on the poor viewing angle and the poor color reproduction of TN panels at that time.

In 2004, Hydis Technologies Co., Ltd licensed its AFFS patent to Japan"s Hitachi Displays. Hitachi is using AFFS to manufacture high end panels in their product line. In 2006, Hydis also licensed its AFFS to Sanyo Epson Imaging Devices Corporation.

It achieved pixel response which was fast for its time, wide viewing angles, and high contrast at the cost of brightness and color reproduction.Response Time Compensation) technologies.

Less expensive PVA panels often use dithering and FRC, whereas super-PVA (S-PVA) panels all use at least 8 bits per color component and do not use color simulation methods.BRAVIA LCD TVs offer 10-bit and xvYCC color support, for example, the Bravia X4500 series. S-PVA also offers fast response times using modern RTC technologies.

A technology developed by Samsung is Super PLS, which bears similarities to IPS panels, has wider viewing angles, better image quality, increased brightness, and lower production costs. PLS technology debuted in the PC display market with the release of the Samsung S27A850 and S24A850 monitors in September 2011.

TFT dual-transistor pixel or cell technology is a reflective-display technology for use in very-low-power-consumption applications such as electronic shelf labels (ESL), digital watches, or metering. DTP involves adding a secondary transistor gate in the single TFT cell to maintain the display of a pixel during a period of 1s without loss of image or without degrading the TFT transistors over time. By slowing the refresh rate of the standard frequency from 60 Hz to 1 Hz, DTP claims to increase the power efficiency by multiple orders of magnitude.

Due to the very high cost of building TFT factories, there are few major OEM panel vendors for large display panels. The glass panel suppliers are as follows:

External consumer display devices like a TFT LCD feature one or more analog VGA, DVI, HDMI, or DisplayPort interface, with many featuring a selection of these interfaces. Inside external display devices there is a controller board that will convert the video signal using color mapping and image scaling usually employing the discrete cosine transform (DCT) in order to convert any video source like CVBS, VGA, DVI, HDMI, etc. into digital RGB at the native resolution of the display panel. In a laptop the graphics chip will directly produce a signal suitable for connection to the built-in TFT display. A control mechanism for the backlight is usually included on the same controller board.

The low level interface of STN, DSTN, or TFT display panels use either single ended TTL 5 V signal for older displays or TTL 3.3 V for slightly newer displays that transmits the pixel clock, horizontal sync, vertical sync, digital red, digital green, digital blue in parallel. Some models (for example the AT070TN92) also feature input/display enable, horizontal scan direction and vertical scan direction signals.

New and large (>15") TFT displays often use LVDS signaling that transmits the same contents as the parallel interface (Hsync, Vsync, RGB) but will put control and RGB bits into a number of serial transmission lines synchronized to a clock whose rate is equal to the pixel rate. LVDS transmits seven bits per clock per data line, with six bits being data and one bit used to signal if the other six bits need to be inverted in order to maintain DC balance. Low-cost TFT displays often have three data lines and therefore only directly support 18 bits per pixel. Upscale displays have four or five data lines to support 24 bits per pixel (truecolor) or 30 bits per pixel respectively. Panel manufacturers are slowly replacing LVDS with Internal DisplayPort and Embedded DisplayPort, which allow sixfold reduction of the number of differential pairs.

The bare display panel will only accept a digital video signal at the resolution determined by the panel pixel matrix designed at manufacture. Some screen panels will ignore the LSB bits of the color information to present a consistent interface (8 bit -> 6 bit/color x3).

With analogue signals like VGA, the display controller also needs to perform a high speed analog to digital conversion. With digital input signals like DVI or HDMI some simple reordering of the bits is needed before feeding it to the rescaler if the input resolution doesn"t match the display panel resolution.

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). "A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel". 20 (11): 995–1001. Bibcode:1973ITED...20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.

K. H. Lee; H. Y. Kim; K. H. Park; S. J. Jang; I. C. Park & J. Y. Lee (June 2006). "A Novel Outdoor Readability of Portable TFT-LCD with AFFS Technology". SID Symposium Digest of Technical Papers. AIP. 37 (1): 1079–82. doi:10.1889/1.2433159. S2CID 129569963.

Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). "Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa". Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.

A TN or Twisted Nematic TFT LCD is a cost-effective high performance LCD. It offers good brightness performance and fast response times. However, it suffers in one key area and that is its viewing cone. TN LCD’s typically have three good viewing angle directions. In these directions the image is typically clear and colors are consistent up to 80 degrees from the center of the LCD. The remaining viewing direction is usually good through 40-50 degrees from center. Afterwards, the image is likely to invert, almost appearing like an x-ray.

The lower the response time the better. Be aware of ISO response time figures and grey to grey (G2G) transition figures as you will need to understand the difference. Screens with a G2G quoted response time use ‘Response Time Compensation’ (RTC) technologies, sometimes referred to as overdrive. These technologies are used to boost pixel response times and in practice can make quite a lot of difference. This is particularly important with non-TN Film panels (i.e. IPS, PVA, MVA etc)

The wider the viewing angles the better. Be wary of how they calculate their figures. Sometimes they will try sneaking things like listed them when CR > 5 instead of when CR > 10 to inflate their numbers. Again real life performance might not match quoted specs. You will normally see TN Film panels listed with a 170/160 viewing angle (a classic indication that the screen is using TN Film technology by the way). IPS-type and VA-type panels will normally feature a 178/178 viewing angle spec, but in reality the performance does vary.

If you’re a gamer then look out for Variable Refresh Rate (VRR) technologies which will significantly improve fluidity in gaming and avoid stuttering, tearing or lag associated with older Vsync technologies. At the moment your choice depends on your graphics card vendor, either AMD FreeSync or NVIDIA G-sync.

A. very important thing to consider is what panel technology the screen uses you are interested in buying. While specs may look similar on paper, performance may vary quite considerably between the models due to the underlying panel technology used. The most common technologies used in the desktop monitor market are TN Film, IPS-type (and similar variants like PLS and AHVA) and VA -type. These are all produced by a range of panel manufacturers and offer a variety of strengths and weaknesses. There is a reasonable amount of talk about panel technologies with many people quick to jump on a bandwagon and claim one is superior to another. To be honest, they all still have their place in the modern market, and due to their different characteristics, can play a key part in finding the right monitor for your use.

PLS (Plane to Line Switching)= S-PLS, a Samsung technology exclusive to them and very similar to LG.Display’s IPS in performance and can therefore be called an “IPS-type” technology

AHVA (Advanced Hyper-Viewing Angle) = developed by AU Optronics as another alternative to LG.Display’s IPS, very similar again and so can be called “IPS-type”

Colour gamut – don’t assume that a higher colour gamut is better! The gamut represents the colour space that the backlighting unit of the monitor allows the screen to display. You need to understand that most normal content is based on a certain colour space (sRGB) and that there can be issues if you view this using a wide gamut screen. See here for more information.

A. Generally nowadays with all the ultra-low response time models available, ghosting caused by slow pixel response times is just not an issue for the majority of users. Performance has improved significantly over the years and blurring and ghosting has been largely eliminated on the faster displays. The use of RTC technologies (overdrive) significantly helps improve response times and speed up pixel transitions. This is particularly important on IPS/VA type displays which can be very slow where RTC is not used. Look out for response time specs quoted with a “G2G” (grey to grey) response time as that should indicate the use of overdrive technologies.

Nowadays screens supporting high refresh rates (120Hz+) input frequencies are becoming more and come common, and these can help reduce motion blur and ghosting and improve gaming performance considerably. They are also able to support higher frame rates than traditional 60Hz displays and some are also capable of supporting 3D stereoscopic content through active shutter glasses. Do be careful of assuming that a screen advertised as supporting 3D is in fact able to support 120Hz though, as some 3D models do not support this and instead use passive methods to produce the 3D effect (see here for more info on 3D technologies). Refresh rate of the panel does have a direct impact on motion clarity and for optimal gaming performance you will want to consider those high refresh rate displays above 60Hz.

Ghosting and motion blur perception may also depend on how susceptible you are as a user, as one person may see no ghosting, another may see lots on the same panel. The best bet is to try and see a TFT in action in a shop and see for yourself, if that’s not possible you will have to settle for the opinions of other users and take the plunge! Also be careful to get an idea of real life performance in practice, and don’t just rely on quoted specs. While they are often a good rough guide to the gaming performance, they are not always reliable.

One area which cannot be eliminated fully through response time improvements is perceived motion blur. This is related to how the human eye tracks movement on hold-type displays like LCD’s. In recent years several methods have been used to help provide improved motion blur for users. Models featuring LightBoost backlights for 3D gaming were found to be “hackable” to bring about motion blur benefits through the use of their strobed backlight system. Other displays have now introduced native strobed backlights to offer similar benefits. Look out for models with Motion Blur Reduction backlights like the BenQ XL2420Z / XL2720Z (Blur Reduction mode), Eizo Foris FG2421 (Turbo 240) and Asus ROG Swift PG278Q (ULMB) for instance. ULMB as a feature is common on NVIDIA G-sync enabled displays where high refresh rate is used.

Have a read here about response times if you are unsure about what specs mean or want more information. Generally modern TN Film panels will offer the fastest response times, and often also support 120Hz input frequencies for 3D support / extended frame rates. Look out for models with a quoted “G2G” response time indicating they also use overdrive which can really help in practice. Modern IPS-type panels can also be very fast where overdrive is applied well, so again look for “G2G” figures. High refresh rate IPS panels are also becoming more common which helps improve motion clarity further. Other technologies like PVA and MVA are unfortunately quite slow in practice by modern standards, even where overdrive or high refresh rates are used. Check reviews to be sure of an individual screens performance wherever possible.

A. As a rule of thumb, it would normally be best to use the digital video connection end to end to connect your device to your monitor. For a PC, this would commonly be DisplayPort, HDMI or DVI which offer a pure digital end to end connection between the graphics card and the monitor. DisplayPort is needed to run the high resolution/high refresh rate panels so you will need to ensure your graphics card has a DP output. Some screens or cards use Mini DP instead of the full size version, but that is simply a different size connection and can be easily inter-changed with “normal” DisplayPort. Cables which are DP at one end, and Mini DP at the other are common and simple to use.

HDMI and DisplayPort are also common digital connections now being offer, but unlike DVI are also capable of carrying audio as well as video. The picture quality should not be any different between DVI, HDMI and DisplayPort in theory as long as no additional video “enhancements” are applied when using one over the other. Bandwidth requirements will vary so this might influence which type you need to use depending on the screen resolution and refresh rate.

Converting between DVI and HDMI is easy and cables are readily available to offer that if needed (keeping in mind you will lose the sound transmission when it reaches the DVI). Converting between DVI/HDMI and DisplayPort is far more tricky and not simple to achieve. It is very hit and miss and working active adapters are expensive. We would advise avoiding the attempt to convert DP to HDMI/DVI if you can.

A. There is a lot of talk about colour depth on TFT screens, now more than ever with the emergence of 6-bit IPS and VA panels. At one time TN Film was the main 6-bit technology but today that is no longer the case. It’s important to put this into perspective though, and not jump on the bandwagon of 8-bit being much, much better than 6-bit. Or even 10-bit being much better than 8-bit.

An 8-bit display would offer a colour palette of 16.7 million colours. They offer a ‘true’ colour palette, and are generally the choice of manufacturers for colour critical displays over 6-bit panels. On the other hand modern 6-bit screens use a range of Frame Rate Control (FRC) technologies to extend the colour palette from 262,144 colours to around 16.7m. In fact on many modern panels these FRC are very good and in practice you’d be hard pressed to spot any real difference between a 6-bit + FRC display and a true 8-bit display. Colour range is good, screens show no obvious gradation of colours, and they show no FRC artefacts or glitches in normal everyday use. Most average users would never notice the difference and so it is more important to think about the panel technology and your individual uses than get bogged down worrying about 6-bit vs. 8-bit arguments.

Manufacturers use 6-bit panels (+FRC) to help keep costs lower. As a result, a modern range of IPS and VA panels is also now produced which use 6-bit colour depth (+FRC) instead of true 8-bit colour depths. At the other end of the scale there are also some panels which can offer support of 10-bit colour depth. Again these come in two flavours, being either a true 10-bit panel (quite rare and expensive) offering 1.07 billion colours or an 8-bit panel with an additional FRC stage added (1.07 billion colours produced through FRC). The 8-bit +FRC panels are of course more common and will often be used to offer “10-bit” support in desktop displays. With 10-bit colour though there is also an additional consideration which is whether you would ever even be able to use this in your work. You can also only make use of this 10-bit support if you have a full end-to-end 10-bit workflow, including a supporting software, graphics card and operating system which is still very rare and expensive for most users. So for many people the use of a 10-bit capable panel is rather meaningless.

While a larger colour space might sound like a good idea, it’s not always for everyone. You need to keep in mind what content you will be viewing on the screen, and what colour space that content is based on. Since sRGB is very common and the standard for many things like Windows and the internet, viewing sRGB content on an extended gamut screen can cause oversaturation of colours and an unrealistic ‘stretching’ of the colours. Reds and greens in particular can appear quite ‘neon’ and some users do not like this. The smaller colour space of the content is, as a very crude description, ‘stretched’ over the larger colour space of the monitor. On the other hand, some applications are colour space aware (e.g. Adobe Photoshop) and so if you are working with extended gamut content, you will prefer an extended gamut screen. I’d certainly recommend reading more into this as it is only a brief summary here. Where a screen has an extended gamut, they sometimes provide an sRGB emulation mode which work to varying degrees. Handy if you might need to use it, but make sure the screen offers a decent performance when in this mode and that it works. At the end of the day, the choice of monitor might very well depend on the colour space you want to work with. For most average users a standard CCFL or W-LED backlit display with a standard sRGB gamut would probably be preferred.

A. The simplest and cheapest way to clean a TFT screen is with a slightly damp cloth; wipe off the left behind water with a towel or similar then smooth/dry completely with a yellow polishing cloth. Be careful not to use products such as toilet paper and kitchen roll as they contain lint and can leave scratches on your beloved screen! Cleaning solution from opticians and lint free clothes for lens cleaning are also very good.

A. Unfortunately dead pixels can be an issue on TFT screens as they are often developed during the manufacturing stage. For retail costs to be kept low the companies cannot afford to make all screens defect-free and check for dead pixels all the time. Pixels can be described in the following ways:

If you want to ensure that you receive a pixel perfect screen (and who wouldn’t at the kind of prices you are paying for the TFT!?!) then you can often pay for pixel checks from some online retailers. Beware though! Never buy a TFT from retailers who offer the pixel check without having the check done as you can be sure the screens they find to be non-perfect will be winging their way to the customers who don’t have the check! The only other option to ensure you get a pixel perfect screen is to check out the panel in a shop in person, then you can see for yourself…..

If you find you have a dead pixel there is not a lot you can do unfortunately. If you have a certain number of dead pixels (usually at least 3 or a certain number centrally on the panel) then the manufacturer will replace the TFT for you, but the number of dead pixels needed before this happens varies between each manufacturer, so check with them before you order if you’re concerned.

If you still have a dead pixel problem, can’t bring it back to life and can’t RMA it under warranty then you can sometimes return it to the stockist if you purchased it online. If you bought online you can take advantage of the “Distance Selling Act” which entitles you to return any item within 7 days as you were not present at the time of purchase. If you are not happy with your TFT you can return it at your cost of postage and often claim a refund or exchange. However, be aware that a lot of places will try and charge you restocking fees and they will almost certainly specify the goods must be packaged and in the same condition as when you received it, so be careful to package it back up nicely. Legally, if the stocker accepts the TFT back as a return governed by the Distance Selling Act, then they are NOT allowed to charge you a restocking fee as covered in the Government Regulations. This selling act is not widely advertised by retailers, but does exist if you really need to use it. You should only have to pay for postage to send it back to them.

LCD stands for “Liquid Crystal Display” and TFT stands for “Thin Film Transistor”. These two terms are used commonly in the industry but refer to the same technology and are really interchangeable when talking about certain technology screens. The TFT terminology is often used more when describing desktop displays, whereas LCD is more commonly used when describing TV sets. Don’t be confused by the different names as ultimately they are one and the same. You may also see reference to “LED displays” but the term is used incorrectly in many cases. The LED name refers only to the backlight technology used, which ultimately still sits behind an liquid crystal panel (LCD/TFT).

As TFT screens are measured differently to older CRT monitors, the quoted screen size is actually the full viewable size of the screen. This is measured diagonally from corner to corner. TFT displays are available in a wide range of sizes and aspect ratios now. More information about the common sizes of TFT screens available can be seen in our section about resolution.

The aspect ratio of a TFT describes the ratio of the image in terms of its size. The aspect ratio can be determined by considering the ratio between horizontal and vertical resolution.

16:9 = wide screen formats such as 1920 x 1080 and 2560 x 1440. 16:9 is commonly used for multimedia displays and TV’s and is increasingly becoming the standard

The resolution of a TFT is an important thing to consider. All TFT’s have a certain number of pixels making up their liquid crystal matrix, and so each TFT has a “native resolution” which matches this number. It is always advisable to run the TFT at its native resolution as this is what it is designed to run at and the image does not need to be stretched or interpolated across the pixels. This helps keep the image at its most clear and at optimum sharpness. Some screens are better than others at running below the native resolution and interpolating the image which can sometimes be useful in games.

You generally cannot run a TFT at a resolution of above its native resolution although some screens have started to offer “Virtual” resolutions, for example “virtual 4k” where the screen will accept a 3840 x 2160 input from your graphics card but scale it back to match the native resolution of the panel which is often 2560 x 1440 in these examples. This whole process is rather pointless though as you lose a massive amount of image quality in doing so.

Ultra-high resolutions must be thought of in a slightly different way. Ultra HD (3840 x 2160) and 4K (4096 x 2160) resolutions are being provided nowadays on standard screen sizes like 24 – 27” for instance. Traditionally as you increased the resolution of panels it was about providing more desktop real estate to work with. However, with those resolutions being so high, and the screen size being relatively small still, the image and text becomes incredibly small if you run the screen at normal scaling at those native resolutions. For instance imagine a 3840 x 2160 resolution on a 24” screen compared with 1920 x 1080. The latter would probably be considered a comfortable font size for most users. These ultra-high resolutions nowadays are about improving image clarity and sharpness, and providing a higher pixel density (measured as pixels per inch = PPI). In doing so, you can improve the sharpness and clarity of an image much like Apple have famously done with their “Retina” displays on iPads and iPhones. To avoid complications with tiny images and fonts, you will then need to enable scaling in your operating system to make everything easier to see. For instance if you enabled scaling at 150% on a 3840 x 2160 resolution, you would end up with a screen real estate equivalent to a 2560 x 1440 panel (3840 / 1.5 = 2560 and 2160 / 1.5 = 1440). This makes text much easier to read and the whole image a more comfortable size, but you then get additional benefits from the higher pixel density instead, which results in a sharper and crisper image.

Generally you will need to take scaling in to consideration when purchasing any ultra-high resolution screen, unless it’s of a very large size. The scaling ability does vary however between different operating systems so be careful. Apple OS and modern Windows (8 and 10) are generally very good at handling scaling for ultra-high res displays. Older operating systems are less capable and may sometimes be complicated. You will also find varying support from different applications and games, and often end up with weird sized fonts or sections that are not scaled up and remain extremely small. A “standard” resolution where you don’t need to worry about scaling might be simpler for most users.

To display this content of this type, your screen needs to be able to 1) handle the full resolution naturally within its native resolution, and 2) be able to handle either the progressive scan or interlaced signal over whatever video interface you are using. If the screen cannot support the full resolution, the image can still be shown but it will be scaled down by the hardware and you won’t be take full advantage of the high resolution content. So for a monitor, if you want to watch 1080 HD content you will need a monitor which can support at least a vertical resolution of 1080 pixels, e.g. a 1920 x 1080 monitor.

Unlike on CRT’s where the dot pitch is related to the sharpness of the image, the pixel pitch of a TFT is related to the distance between pixels. This value is fixed and is determined by the size of the screen and the native resolution (number of pixels) offered by the panel. Pixel pitch is normally listed in the manufacturers specification. Generally you need to consider that the ‘tighter’ the pixel pitch, the smaller the text will be, and potentially the sharper the image will be. To be honest, monitors are normally produced with a sensible resolution for their size and so even the largest pixel pitches return a sharp images and a reasonable text size. Some people do still prefer the larger-resolution-crammed-into-smaller-screen option though, giving a smaller pixel pitch and smaller text. It’s down to choice and ultimately eye-sight.

For instance you might see a 35″ ultra-wide screen with only a 2560 x 1080 resolution which would have a 0.3200 mm pixel pitch. Compare this to a 25″ screen with 2560 x 1400 resolution and 0.2162 mm pixel pitch and you can see there will be a significant different in font size and image sharpness. There are further considerations when it comes to the pixel pitch of ultra-high resolution displays like Ultra HD and 4K. See the section on PPI for more information.

Instead manufacturers are now focusing on delivering higher resolutions in to existing panel sizes, not for the purpose of providing more desktop real-estate, but for the purpose of improving image sharpness and picture quality. Apple started this trend with their “Retina Displays” used in iPads and iPhones, improving image sharpness and clarity massively. It is common now to see smaller screens such as 24″ and 27″ for instance, but with high resolutions like 3840 x 2160 (Ultra HD) or even 5120 x 2880 (5K). By packing more pixels in to the same screen size which would typically offer a 2560 x 1440 resolution, panel manufacturers are able to provide much smaller pixel pitches and improve picture sharpness and clarity. To measure this new way of looking at resolution you will commonly see the spec of ‘Pixels Per Inch’ (PPI) being used.

Of course the problem with this is that if you run a screen as small as 27″ with a 5K resolution, the font size is absolutely tiny by default. You get a massive boost of desktop real-estate, just like when moving from 1920 x 1080 to 2560 x 1440, but that’s not the purpose of these higher resolutions now. To overcome this you need to use the scaling options in your Operating System software to scale the image and make it more usable. Windows provides for instance scaling options like 125% and 150% within the control panel. On a 3840 x 2160 Ultra HD resolution if you use a 150% scaling option for example you will in effect reduce the desktop area by a third, resulting in the same desktop area as a 2560 x 1440 display (i.e. 2560 x 150% = 3840). The OS scaling makes font sizes more comfortable and reasonable, but you maintain the sharp picture quality and small pixel pitch of the higher resolution panel. A 3840 x 2160 res panel scaled at 150% in Windows will look sharper and crisper than a 2560 x 1440 native panel without scaling, despite the fact both would have the same effective desktop area available.

While this aspect is not always discussed by display manufacturers it is a very important area to consider when selecting a TFT monitor. The LCD panels producing the image are manufactured by many different panel vendors and most importantly, the technology of those panels varies. Different panel technologies will offer different performance characteristics which you need to be aware of. Their implementation is dependent on the panel size mostly as they vary in production costs and in target markets. The four main types of panel technology used in the desktop monitor market are:

TN Film was the first panel technology to be widely used in the desktop monitor market and is still regularly implemented in screens of all sizes thanks to its comparatively low production costs. TN Film is generally characterized by good pixel responsiveness making it a popular choice for gamer-orientated screens. Where overdrive technologies are also applied the responsiveness is improved further. TN Film panels are also available supporting 120Hz+ refresh rates making them a popular choice for stereoscopic 3D compatible screens. While older TN Film panels were criticized for their poor black depth and contrast ratios, modern panels are actually very good in this regard, often producing a static contrast ratio of up to 1000:1. Perhaps the main limitation with TN Film technology is its restrictive viewing angles, particularly in the vertical field. While specs on paper might look promising, in reality the viewing angles are restrictive and there are noticeable contrast and gamma shifts as you change your line of sight. TN Film panels are normally based around a 6-bit colour depth as well, with a Frame Rate Control (FRC) stage added to boost the colour palette. They are often excluded from higher end screens or by colour enthusiasts due to this lower colour depth and for their viewing angle limitations. TN Film panels are regularly used in general lower end and office screens due to cost, and are very popular in gaming screens thanks to their low response times and high refresh rate support. Pretty much all of the main panel manufacturers produce TN Film panels and all are widely used (and often interchanged) by the screen manufacturers.

IPS was originally introduced to try and improve on some of the drawbacks of TN Film. While initially viewing angles were improved, the panel technology was traditionally fairly poor when it came to response times and contrast ratios. Production costs were eventually reduced and the main investor in this technology has been LG.Display (formerly LG.Philips). The original IPS panels were developed into the so-called Super IPS (S-IPS) generation and started to be more widely used in mainstream displays. These were characterized by their good colour reproduction qualities, 8-bit colour depth (without the need for Frame Rate Control) and very wide viewing angles. These panels were traditionally still quite slow when it came to pixel response times however and contrast ratios were mediocre. In more recent years a change was made to the pixel alignment in these IPS panels (see our detailed panel technology article for more information) which gave rise to the so-called Horizontal-IPS (H-IPS) classification. With the introduction of overdrive technologies, response times were improved significantly, finally making IPS a viable choice for gaming. This has resulted more recently in IPS panels being often regarded as the best all-round technology and a popular choice for display manufacturers in today’s market. Improvements in energy consumption and reduced production costs lead to the generation of so-called e-IPS panels. Unlike normal 8-bit S-IPS and H-IPS classification panels, the e-IPS generation worked with a 6-bit + FRC colour depth. Developments and improvements with colour depths also gave rise to a generation of “10-bit” panels with some manufacturers inventing new names for the panels they were using, including the co-called Performance-IPS (p-IPS). It is important to understand that these different variants are ultimately very similar and the names are often interchanged by different display vendors. For more information, see our detailed panel technologies guide.

Nowadays IPS panels are produced and developed by several leading panel manufacturers. LG.Display technically own the IPS name and continue to invest in this popular technology. Samsung began production of their very similar PLS (Plane to Line Switching) technology, as did AU Optronics with their AHVA (Advanced Hyper Viewing Angle). These are all so similar in performance and features that they can be simply referred to now as “IPS-type”. Indeed monitor manufacturers will normally stick to the common IPS name but the underlying panel may be produced by any number of different manufacturers investing in this type of panel tech. AU Optronics have done a good job with finally increasing the refresh rate of their IPS panels, and making them a more viable option for gamers. Native 144Hz IPS-type panels are now available and response times continue to be reduced as well. Modern IPS panels are characterized by decent response times, if not quite as fast as TN Film they are certainly more fluid than older panels. Contrast ratios are typically around 1000:1 and viewing angles continue to be the widest and most stable of any panel technology. You will find varying colour depths including 6-bit+FRC and 8-bit commonly being used, although this makes little difference in practice. One of the remaining limitations with IPS-type technologies are the so-called “IPS glow”, where darker content introduces a pale glow when viewed from an angle. It’s a characteristic of the panel technology and pretty hard to avoid without additional filters being added to the panels. On larger and wider screens some people find this glow distracting and problematic.

The original early VA panels were quickly scrapped due to their poor viewing angles, and in their place came the two main types of VA matrix. Multi-Domain Vertical Alignment (MVA) and Patterned Vertical Alignment (PVA) panels. These VA variants were characterized by their reasonably wide viewing angles, being better than TN Film but not as wide as IPS. They were originally poor when it came to pixel response times but offered 8-bit colour depths and the best static contrast ratios of all the technologies discussed here. Traditionally VA panels were capable of static contrast ratios of around 1000 – 1200:1 but this has even been improved now to 3000:1 and above. Until very recently VA panels remained very slow and so were not really suitable for gaming. However during 2012 we saw advancements with the latest generation of VA panels and through the use of overdrive technologies this has been significantly improved. Perhaps the main limitation with VA panels is still their viewing angles when compared with popular IPS panel options. Gamma and contrast shifts can be an issue and the technology also suffers from an inherent off-centre contrast shift issue which can be distracting to some users. Through the years we have seen several different generations of VA panels. AU Optronics are the main manufacturer of MVA matrices, and we have seen the so-called Premium-MVA (P-MVA) and Advanced-MVA (AMVA) generations emerge. Chi Mei Innolux (previously Chi Mei Optoelectronics / CMO) also make their own variant of MVA which they call Super-MVA (S-MVA).The only manufacturer of PVA panels is Samsung as it is their own version of VA technology. We have seen several generations from them including Super-PVA (S-PVA) and cPVAandSVA. For more information, see our detailed panel technologies guide.

This technology was developed by Sharp for use in some of their TFT displays. It consists of several improvements that Sharp claim to have made, mainly to counter the drawbacks of the popular TN Film technology. They have introduced an Anti-Glare / Anti-Reflection (AGAR) screen coating which forms a quarter-wavelength filter. Incident light is reflected back from front and rear surfaces 180° out of phase, thus canceling reflection rather diffusing it as others do. As well as reducing glare and reflection from the screen, this is marketed as being able to offer deeper black levels. Sharp also claim to offer better contrast ratios than any competing technology (VA and IPS); but with more emphasis on improving these other technologies, this is probably not the case with more modern panels. There are very few ASV monitors around really, with the majority of the market being dominated by TN, VA and IPS panels.

This technology was developed by BOE Hydis, and is not really very widely used in the desktop TFT market, more in the mobile and tablet sectors. It is worth mentioning however in case you come across displays using this technology. It was developed by BOE Hydis to offer improved brightness and viewing angles to their display panels and claims to be able to offer a full 180/180 viewing angle field as well as improved colours. This is basically just an advancements from IPS and is still based on In Plane technology. They claim to “modify pixels” to improve response times and viewing angles thanks to improved alignment. They have also optimised the use of the electrode surface (fringe field effect), removed shadowed areas between pixels, horizontally aligned electric fields and replaced metal electrodes with transparent ones. More information about AFFS can be found here.

This panel technology was developed by NEC LCD, and is reported to offer wide viewing angles, fast response times, high luminance, wide colour gamut and high definition resolutions. Of course, there is a lot of marketing speak in there, and the technology is not widely employed in the mainstream monitor market. Wide viewing angles are possible thanks to the horizontal alignment of liquid crystals when electrically charged. This alignment also helps keep response times low, particularly in grey to grey transitions. Their SFT range also offers high definition resolutions and are commonly used in medical displays where extra fine detail is required.

Take for instance this example response time graph (rise times from 0 > x) I have put together. The X-axis defines the grey scale ranging from code 0 to code 255, and the Y-axis shows the response time across this range. As you progress to the right of the graph, the transitions are getting progressively lighter. So for instance at code 100 the transition is from black > dark grey, but at code 200 the transition is from black > light grey. At code 255, this is the change from black > white and is traditionally the fastest transition. It is the fastest because this is the widest change and therefore the largest voltage is applied to the liquid crystals. For many years, manufacturers have quoted the fastest transition of the panel as the figure for ‘response time’. This was always at the black > white > black transition and so this became accepted as the ISO standard norm for measuring response time. If this graph were a real panel, it would very likely be quoted as a 10ms screen and shows a characteristic curve for a traditional, non-overdriven, TN Film panel.

One thing to note regarding pixel response time is that the overall performance of the TFT will also depend on the technology of the panel used. TN film panels offer response time graphs similar to that above, but screens based on traditional VA / IPSvariant panels can show response time graphs more like this (we are assuming for now non-overdriven panels):

This is again a mock up, but shows a typical curve shape you may expect from a VA / IPS panel (not using overdrive) when compared with TN film. Although a VA/IPS screen might be quoted as perhaps 12ms for instance, this might not mean it is as reactive as a 12ms TN film panel. Again, it is a good idea to check for reviews which measure the response time across the whole range as well as to consider real-life responsiveness tests such as those we carry out in our reviews.

Overdrive or ‘Response Time Compensation’ (RTC) is a technology which is designed to boost the response times of pixels across all transitions, with particular focus on improving the grey to grey changes which is the most important as those transitions are far more common in real-life uses. It is achieved by sending an over-voltage to the pixels to make them change orientation more quickly. While the full black > white change remains largely unchanged (since it already received the maximum voltage anyway), improvements across other transitions are often dramatic. With the introduction of overdriven panels the ISO point is not always the fastest transition any more, and so if a monitor has a response time quoted as “grey to grey / G2G” then you can be pretty certain it is using overdrive technology. The manufacturers still want to quote the fastest response time of their panel and show the improvements they have made though, but be wary of this change away from the ISO standard of quoting response times. The ISO response times have hit a wall really with TN Film stuck at 5 – 8ms, IPS stuck at around 16ms and MVA/PVA stuck at about 12ms. However, with the introduction of overdrive technologies, the more important grey to grey transitions are now significantly improved, and response times of 1 – 5ms G2G are now common place. These technologies have allow significant improvements in all panel technologies, but particularly in IPS and VA panels where response times were previously poor.

Some reviews sites including TFTCentral have access to advanced photosensor (photodiodе + low-noise operational amplifier) and oscilloscope measurement equipment which allows them to measure response time as detailed above. See our article about response times for more information on that method. Graphs showing response time according to their equipment are produced. Other sites rely on observed responsiveness to compare how well a panel can perform in practice and what a user might see in normal use. We think it is important to study both methods if possible to give a fuller picture of a panels performance. For visual tests TFTCentral uses a program called PixPerAn (developed by Prad.de) which is good for comparing monitor responsiveness with its series of tests. The favourite seems to be the moving car test as shown here:

In addition to pixel response time measurements and visual tests described above, it is also possible to capture the levels of blurring and smearing the human eye will experience on a display. This is achieved using a pursuit camera setup. They are simply cameras which follow the on-screen motion and are extremely accurate at measuring motion blur, ghosting and overdrive artefacts of moving images. Since they simulate the eye tracking motion of moving eyes, they can be useful in giving an idea of how a moving image appears to the end user. It is the blurring caused by eye tracking on continuously-displayed refreshes (sample-and-hold) that we are keen to analyse with this new approach. This is not pixel persistence caused by response times; but a different cause of display motion blur which cannot be captured using static camera tests. Low response times do have a positive impact on motion blur, and higher refresh rates also help reduce blurring to a degree. It does not matter how low response times are, or how high refresh rates are, you will still see motion blur from LCD displays under normal operation to some extent and that is what this section is designed to measure. Further technologies specifically designed to reduce perceived motion blur are required to eliminate the blur seen on these type of sample-and-hold displays which we will also look at.

These tests capture the kind of blurring you would see with the naked eye when tracking moving objects across the screen (example from the Asus ROG Swift PG279Q). As you increase the refresh rate the perceived blurring is reduced, as refresh rate has a direct impact on motion blur. It is not eliminated entirely due to the nature of the sample-and-hold LCD display and the tracking of your eyes. No matter how fast the refresh rate and pixel response times are, you cannot eliminate the perceived motion blur without other methods.Tests like the above would give you an idea of the kind of perceived motion blur range when using the particular screen without any bur reduction mode active.

The Contrast Ratio of a TFT is the difference between the darkest black and the brightest white it is able to display. This is really defined by the pixel structure and how effectively it can let light through and block light out from the backlight unit. As a rule of thumb, the higher the contrast ratio, the better. The depth of blacks and the brightness of the whites are better with a higher contrast ratio. This is also referred to as the static contrast ratio.

When considering a TFT monitor, a contrast ratio of 1000:1 is pretty standard nowadays for TN Film and IPS-type panels. VA-type panels can offer static contrast ratios of 3000:1 and above which are significantly higher than other competing panel technologies.

Some technologies boast the ability to dynamically control contrast (Dynamic Contrast Ratio – DCR) and offer much higher contrast ratios which are incredibly high (millions:1 for instance!). Be wary of these specs as they are dynamic only, and the technology is not always very useful in practice. Traditionally, TFT monitors were said to offer poor black depth, but with the extended use of VA panels, the improvements from IPS and TN Film technology, and new Dynamic Contrast Control technologies, we are seeing good improvements in this area. Black point is also tied in to contrast ratio. The lower the black point, the better, as this will ensure detail is not lost in dark image when trying to distinguish between different shades.

Brightness as a specification is a measure of the brightest white the TFT can display, and is more accurately referred to as its luminance. Typically TFT’s are far too bright for comfortable use, and the On Screen Display (OSD) is used to turn the brightness setting down. Brightness is measure in cd/m2 (candella per metre squared). Note that the recommended brightness setting for a TFT screen in normal lighting conditions is 120 cd/m2. Default brightness of screens out of the box is regularly much higher so you need to consider whether the monitor controls afford you a decent adjustment range and the ability to reduce the luminance to a comfortable level based on your ambient lighting conditions. Different uses may require different brightness settings as well so it is handy when reviews record the luminance range possible from the screen as you adjust the brightness control from 100 to 0%.

The colour depth of a TFT panel is related to how many colours it can produce and should not be confused with colour space (gamut). The more colours available, the better the colour range can potentially be. Colour reproduction is also different however as this related to how reliably produced the colours are compared with those desired.

The colour depth of a panel is determined really by the number of possible orientations of each sub pixel (red, blue and green). These different orientations basically determine the different shade of grey (or colours when filtered in the specific way via RGB sub pixels) and the more “steps” between each shade, the more possible colours the panel can display.

At the lower end, TN Film panels are normally quite economical, and their sub pixels only have 64 possible orientations each, giving rise to a true colour depth of only 262,144 (i.e. 64 steps on each RGB = 64 x 64 x 64 = 18). This is also referred to commonly s 18-bit colour (i.e. 6 bits per RGB sub pixel = 6 + 6 + 6) This colour depth is pretty limited and so in order to reach 16 million colours and above, panel manufacturers commonly use two technologies: Dithering and Frame Rate Control (FRC). These terms are often interchanged, but strictly can mean different things. These technologies simulate other colours allowing the colour depth to improve to typically 16.2 million colours.

Spatial Dithering – The dithering method involves assigning appropriate colour values from the available colour palette to close-by pixels in such a way that it gives the impression of a new colour tone which otherwise could not have been created at all. In doing so, there complex mappings according to which the ground colours are mutually assigned, otherwise it could result in colour noise / dithering noise. Dithering can be used to allow 6-Bit panels, like TN Film, to show 16.2 million perceived colours. This can however sometimes be detectable to the user, and can result in chessboard like patterns being visible in some cases.

Frame Rate Control / Temporal Dithering– The other method is Frame-Rate-Control (FRC), also referred to sometimes as temporal dithering. This works by combining four colour frames as a sequence in time, resulting in perceived mixture. In basic terms, it involves flashing between two colour tones rapidly to give the impression of a third tone, not normally available in the palette. This allows a total of 16.2 reproducible million colours. Thanks to Frame-Rate-Control, TN panel monitors have come pretty close to matching the colours and image quality of VA or IPS panel technology, but there are a number of FRC algorithms which vary in their effectiveness. Sometimes, a twinkling artefact can be seen, particularly in darker shades, which is a side affect of such technologies. Some TN Film panels are now quoted as being 16.7 million colours, and this is down to new processes allowing these panels to offer a better colour depth compared with older TN panels.

Colour gamut in TFT monitors refers to the range of colours the screen is capable of displaying, and how much of a given reference colour space it might be able to display. It is ultimately linked to backlight technology and not to the panel itself.

Laser Displays are capable of producing the biggest colour gamut for a system with three basic colours, but even a laser display cannot reproduce all the colours the human eye can see, although it is quite close to doing that. However, in today’s monitors, both CRT and LCD (except for some models I’ll discuss below), the spectrum of each of the basic colours is far from monochromatic. In the terms of the CIE diagram it means that the vertexes of the triangle are shifted from the border of the diagram towards its centre.

Traditionally, LCD monitors were capable of giving approximate coverage of the sRGB reference colour space as shown in the diagram above. This is defined by the backlighting used in these displays – Cold-cathode fluorescent lamps (CCFL) that are employed which emit radiation in the ultraviolet range which is transformed into white colour with the phosphors on the lamp’s walls. These backlight lamps shine through the LCD panel, and through the RGB sub-pixels which act as filters for each of the colours. Each filter cuts a portion of spectrum, corresponding to its pass-band, out of the lamp’s light. This portion must be as narrow as possible to achieve the largest colour gamut.

To help develop and improve on the colour space a screen is capable of displaying a new generation CCFL backlighting was introduced. These so-called “wide gamut” backlights allow a gamut coverage of typically 92 – 102% of the NTSC colour space. There is a difference in practice which all users should be able to detect. The colour space available is extended mainly in green shades as you can see from the image above. Red coverage is also extended in some cases. This extended colour space sounds appealing on face value since the screens featuring WCG-CCFL backlighting can offer a broader range of colours. Manufacturers will often promote the colour space coverage of their screens with these high figures. In practice you need to consider what impact this would have on your use.

Of course the opposite is true if in fact you are working with content which is based on a wider colour space. In photography, the Adobe RGB colour space is often used and is wider than the sRGB reference. If you are working with wide gamut content, with wide gamut supported applications, you would want a screen that can correctly display the full range of colours. This could not be achieved using a traditional CCFL backlit display with only sRGB coverage, and so a wide gamut screen would be needed. Wide gamut displays are often aimed at colour enthusiasts and professional uses as a result.

LED backlighting has now become the norm for desktop monitors and is available in a few variations. The most common is White-LED (W-LED), which is a replacement for standard CCFL backlighting. The LED’s are placed in a line along the edge of the matrix, and the uniform brightness of the screen is ensured by a special design of the diffuser. The colour gamut is limited to sRGB as standard (around 68 – 72% NTSC) but the units are cheaper to manufacturer and so are being utilised in more and more screens, even in the more budget range. They do have their environmental benefits as they can be recycled, and they have a thinner profile making them popular in super-slim range models and notebook PC’s. It is possible to extend the colour gamut of W-LED displays using “Quantum Dot” technologies which are fairly new.

RGB LED backlighting consists of an LED backlight based on RGB triads, each triad including one red, one green and one blue LED. With RGB LED backlighting the spectrum of e