17 flat lcd monitors free sample

* Rewards 3% back excludes taxes and shipping. Rewards are issued to your online Dell Rewards Account (available via your Dell.com My Account) typically within 30 business days after your order’s ship date. Rewards expire in 90 days (except where prohibited by law). “Current rewards balance” amount may not reflect the most recent transactions. Check Dell.com My Account for your most up-to-date reward balance. Total rewards earned may not exceed $2,000 within a 3-month period. Outlet purchases do not qualify for rewards. Expedited Delivery not available on certain TVs, monitors, batteries and adapters, and is available in Continental (except Alaska) U.S. only. Other exceptions apply. Not valid for resellers and/or online auctions. Offers and rewards subject to change without notice, not combinable with all other offers. See Dell.com/rewardsfaq. $50 in bonus rewards for Dell Rewards Members who open a new Dell Preferred Account (DPA), or Dell Business Credit (DBC) account on or after 8/10/2022. $50 bonus rewards typically issued within 30 business days after DPA or DBC open date.

*Expedited Delivery: * Expedited Delivery not available on certain TVs, monitors, batteries and adapters, and is available in Continental (except Alaska) U.S. only. Other exceptions apply. Not valid for resellers and/or online auctions. Offers subject to change, not combinable with all other offers. See Dell.com/rewardsfaq.

Unused electronics are the bane of the modern life. Perfectly functional gadgets sit quietly in a corner of the store room, doing nothing. If you"re wondering what to do with old computer monitors, here are a few easy ideas to repurpose unused screens.

Perhaps the best thing to do with an old flat-screen monitor is a DIY DAKboard. The DAKboard is a LCD wall display that shows the current time, weather forecast, calendar events, stock quotes, fitness data, and news headlines. It"s all displayed on a soothing photo. You could buy an official DAKboard, but the makers themselves have shown how to build your own wall display with a Raspberry Pi. when you can build one for far less money and a little geeky fun, the choice is obvious.

Basically, you will be cutting out the polarizing film of the old LCD monitor. This film will then be put on a simple pair of glasses. Now your screen appears white, but the glasses can "see" the content. It"s one of the best ways to keep prying eyes out of your PC.

If you have a broken old LCD monitor, it can be re-purposed into a usable mirror; but if you have a working old LCD monitor, adding a Raspberry Pi can turn it into a smart magic mirror!

If you"re on a tight budget for a first-time DIY project, consider the $100 smart mirror. It"s not the best version of turning an LCD monitor into a smart mirror, but you"ll get the basic features and not spend a bomb.

All desktop operating systems support the ability to use dual monitors. It"s pretty easy to setup dual monitors on Windows, and you can then customize how you use the two spaces. To connect two monitors, you will likely need a graphics card with multiple HDMI ports, or use an HDMI and a VGA port on desktops.

Like any gadget, monitors have a limited shelf life. If you"re looking to upgrade, you now have a few ideas of what to do with your old monitor. And that age should influence which project you chose. For example, given the effort involved in building a smart mirror, don"t go with a screen that"s already shown signs of trouble. The Raspberry Pi-based projects are usually the easiest to keep changing.

Shopping for monitors can be daunting. Not all LCD monitors are created equal, and a minor difference in specs can signify a major difference in performance. It"s important to know what features are vital to the activities that you intend to use your monitor for. Once you understand what specifications are important to you, eBay"s vast selection of 17-inch LCD monitors is certain to have a model that fits your needs.What do the specifications mean?

It can be difficult to understand the technical jargon that manufacturers use to describe the capabilities of their monitors, as well as what the numbers and abbreviations actually mean when it comes to device performance and what applications they"re most useful for. Even enthusiasts may struggle with the significance of some of the more obscure specifications. Some of the specs that it"s important to understand are:Resolution - This is the length of the screen"s border, in pixels. A higher number means more pixels, and a better picture. 1080p is considered full HD, while 2160p ("4k") and 4320p ("8k") are considered Ultra HD.

Refresh rate - This is the frequency with which the monitor updates ("refreshes") its picture. Measured in Hertz, which measures updates per second, a high refresh rate is ideal for gaming monitors.

Response time - This refers to the length of time it takes for a single pixel to turn from white to black, measured in milliseconds (ms). A lower number means a quicker response time. Monitors featuring response times as fast as 1ms are available but currently have a trade-off in color fidelity and viewing angle.

The main features to look for in a gaming monitor are a high refresh rate, low response time, and high resolution. Color fidelity and viewing angle may be less important to anyone looking for a competitive edge in computer games, and an extremely responsive monitor is helpful in keeping up with the information from fast-paced computer games.What specifications should you seek in a 17-inch monitor?

All desktops require an external monitor to function. Computer monitors, like PCs, come in all shapes and sizes. Finding the perfect PC monitor can help take your computer experience to the next level. Whether you are looking for a high resolution external monitor to make your home office more ergonomic or you want a premium option to make gaming more robust, Micro Center has the computer monitor you need to boost productivity and enjoyment when you are using your computer.

Gaming monitors are specialized displays designed to have the lowest response times possible to stay ahead of the competition. PC monitors for office use may have slower response times but are more affordable and capable of performing general use tasks to improve productivity, viewing angles, and more.

At Micro Center, we proudly offer the best monitors for gamers, creatives, and more to help boost connectivity and the viewing experience with your Apple or PC computer. Discover your new high def LED, IPS, or LCD monitor here.

Resolution is important to choosing a monitor for gaming or enjoying streaming media with the best picture. Go for a 4K ultra high definition (4K UHD) or 8K monitor if you want the best resolution possible. With more than 8 million pixels, a UHD monitor will undoubtedly enhance the visuals of any gaming or video streaming experience. Ultrawide monitors are also great for creating cinematic viewing angles and making you feel like you’re in the theatre.

Additionally, gaming monitors have features that make them work better with your gaming PC. For example, the Nvidia G Sync or AMD FreeSync are used in some gaming monitors to provide a smoother refresh rate to make gameplay smoother and more enjoyable overall. Our selection of FreeSync and G Sync compatible monitors will help you maximize performance of your Nvidia or AMD graphics card.

Computer monitors are available from all the name brands such as Acer, Samsung, Dell, HP, and ASUS. Dell monitors are a popular choice among many offices and professionals because of their wide range of screen sizes and features. No matter if you are looking for a comfortable widescreen option for your home office or a gaming monitor with special features from Nvidia and AMD, Micro Center has the HD monitor you need!

Our school just received a computer donation from a local company who is updating their equipment. We now have 20 (gently used) 17″ flat panel monitors. The equipment is clean, in great working order, and includes all the power cords and video cables. This is AWESOME!!

I thank the donor for the equipment and start to load as many flat panels onto my utility cart as I can carry. My plan is to replace the old CRT monitors that weigh about 50 pounds each and take up considerable real estate on the teacher’s desk with the new equipment. This is AWESOME!!

I immediately get to work swapping the outdated equipment with a sleeker model. I soon discover that lugging each of those old monitors around is back breaking work, literally! They are so heavy! However, the effort is worthwhile. Each monitor has built in speakers and takes up hardly any room on the desk. The teachers are so pleased because now they actually have room to work. This is AWESOME!!

I have been piling the old CRT monitors in the computer lab. They are shoved below the desks and stacked all over the office. I look around at my computer graveyard. I have old equipment everywhere and no one wants this dated technology. Getting rid of these boat anchors is not going to be an easy task. This is NOT AWESOME!!

I start to consider my options. If I take them to the garbage dump I must PAY a disposal fee. Not only is this going to be expensive, but I have almost 20 heavy monitors that will never fit into my little car. It would take me at least 5 trips to dispose of them this way and the truth is that even if this were a realistic option, the school cannot afford to get rid of them.

The next option I explore is to check with the manufacturer. I hope that if the school paid a recycling fee when the units were purchased perhaps they might take them back. However, I discover that the old CRT monitors were donated a few years back and they cannot be returned to the donor, nor the manufacturer.

I then investigate if I can drop them off at the reuse center. Unfortunately, they don’t want them either. Apparently, it is their policy to only take monitors manufactured after 2006.

I stand in the computer lab, surrounded by CRT monitors, frustrated with my predicament. I then have an idea. I call my local Staples, which is an office supply store.

Success! Staples will take them. However there is a limit of 3 monitors per person, per day. I’m going to have to find some volunteers to help me out, but at least there is no fee for disposing of them. This is great news because the school has a limited budget.

In the end, I manage to get rid of the old equipment and the teachers are pleased to have fancy new monitors. Report cards need to go out soon. The new computer donation is going to make writing report cards so much more fun!! (LOL)

The display in modern monitors is typically an LCD with LED backlight, having by the 2010s replaced CCFL backlit LCDs. Before the mid-2000s,CRT. Monitors are connected to the computer via DisplayPort, HDMI, USB-C, DVI, VGA, or other proprietary connectors and signals.

Originally, computer monitors were used for data processing while television sets were used for video. From the 1980s onward, computers (and their monitors) have been used for both data processing and video, while televisions have implemented some computer functionality. In the 2000s, the typical display aspect ratio of both televisions and computer monitors has changed from 4:3 to 16:9.

Modern computer monitors are mostly interchangeable with television sets and vice versa. As most computer monitors do not include integrated speakers, TV tuners, nor remote controls, external components such as a DTA box may be needed to use a computer monitor as a TV set.

Early electronic computer front panels were fitted with an array of light bulbs where the state of each particular bulb would indicate the on/off state of a particular register bit inside the computer. This allowed the engineers operating the computer to monitor the internal state of the machine, so this panel of lights came to be known as the "monitor". As early monitors were only capable of displaying a very limited amount of information and were very transient, they were rarely considered for program output. Instead, a line printer was the primary output device, while the monitor was limited to keeping track of the program"s operation.

Multiple technologies have been used for computer monitors. Until the 21st century most used cathode-ray tubes but they have largely been superseded by LCD monitors.

The first computer monitors used cathode-ray tubes (CRTs). Prior to the advent of home computers in the late 1970s, it was common for a video display terminal (VDT) using a CRT to be physically integrated with a keyboard and other components of the workstation in a single large chassis, typically limiting them to emulation of a paper teletypewriter, thus the early epithet of "glass TTY". The display was monochromatic and far less sharp and detailed than on a modern monitor, necessitating the use of relatively large text and severely limiting the amount of information that could be displayed at one time. High-resolution CRT displays were developed for specialized military, industrial and scientific applications but they were far too costly for general use; wider commercial use became possible after the release of a slow, but affordable Tektronix 4010 terminal in 1972.

By the end of the 1980s color progressive scan CRT monitors were widely available and increasingly affordable, while the sharpest prosumer monitors could clearly display high-definition video, against the backdrop of efforts at HDTV standardization from the 1970s to the 1980s failing continuously, leaving consumer SDTVs to stagnate increasingly far behind the capabilities of computer CRT monitors well into the 2000s. During the following decade, maximum display resolutions gradually increased and prices continued to fall as CRT technology remained dominant in the PC monitor market into the new millennium, partly because it remained cheaper to produce.

There are multiple technologies that have been used to implement liquid-crystal displays (LCD). Throughout the 1990s, the primary use of LCD technology as computer monitors was in laptops where the lower power consumption, lighter weight, and smaller physical size of LCDs justified the higher price versus a CRT. Commonly, the same laptop would be offered with an assortment of display options at increasing price points: (active or passive) monochrome, passive color, or active matrix color (TFT). As volume and manufacturing capability have improved, the monochrome and passive color technologies were dropped from most product lines.

The first standalone LCDs appeared in the mid-1990s selling for high prices. As prices declined they became more popular, and by 1997 were competing with CRT monitors. Among the first desktop LCD computer monitors was the Eizo FlexScan L66 in the mid-1990s, the SGI 1600SW, Apple Studio Display and the ViewSonic VP140vision science remain dependent on CRTs, the best LCD monitors having achieved moderate temporal accuracy, and so can be used only if their poor spatial accuracy is unimportant.

High dynamic range (HDR)television series, motion pictures and video games transitioning to widescreen, which makes squarer monitors unsuited to display them correctly.

Organic light-emitting diode (OLED) monitors provide most of the benefits of both LCD and CRT monitors with few of their drawbacks, though much like plasma panels or very early CRTs they suffer from burn-in, and remain very expensive.

Radius of curvature (for curved monitors) - is the radius that a circle would have if it had the same curvature as the display. This value is typically given in millimeters, but expressed with the letter "R" instead of a unit (for example, a display with "3800R curvature" has a 3800mm radius of curvature.

Dot pitch represents the distance between the primary elements of the display, typically averaged across it in nonuniform displays. A related unit is pixel pitch, In LCDs, pixel pitch is the distance between the center of two adjacent pixels. In CRTs, pixel pitch is defined as the distance between subpixels of the same color. Dot pitch is the reciprocal of pixel density.

Pixel density is a measure of how densely packed the pixels on a display are. In LCDs, pixel density is the number of pixels in one linear unit along the display, typically measured in pixels per inch (px/in or ppi).

Contrast ratio is the ratio of the luminosity of the brightest color (white) to that of the darkest color (black) that the monitor is capable of producing simultaneously. For example, a ratio of 20,000∶1 means that the brightest shade (white) is 20,000 times brighter than its darkest shade (black). Dynamic contrast ratio is measured with the LCD backlight turned off. ANSI contrast is with both black and white simultaneously adjacent onscreen.

Color depth - measured in bits per primary color or bits for all colors. Those with 10bpc (bits per channel) or more can display more shades of color (approximately 1 billion shades) than traditional 8bpc monitors (approximately 16.8 million shades or colors), and can do so more precisely without having to resort to dithering.

Refresh rate is (in CRTs) the number of times in a second that the display is illuminated (the number of times a second a raster scan is completed). In LCDs it is the number of times the image can be changed per second, expressed in hertz (Hz). Determines the maximum number of frames per second (FPS) a monitor is capable of showing. Maximum refresh rate is limited by response time.

On two-dimensional display devices such as computer monitors the display size or view able image size is the actual amount of screen space that is available to display a picture, video or working space, without obstruction from the bezel or other aspects of the unit"s design. The main measurements for display devices are: width, height, total area and the diagonal.

With the introduction of flat panel technology, the diagonal measurement became the actual diagonal of the visible display. This meant that an eighteen-inch LCD had a larger viewable area than an eighteen-inch cathode-ray tube.

Until about 2003, most computer monitors had a 4:3 aspect ratio and some had 5:4. Between 2003 and 2006, monitors with 16:9 and mostly 16:10 (8:5) aspect ratios became commonly available, first in laptops and later also in standalone monitors. Reasons for this transition included productive uses for such monitors, i.e. besides Field of view in video games and movie viewing, are the word processor display of two standard letter pages side by side, as well as CAD displays of large-size drawings and application menus at the same time.LCD monitors and the same year 16:10 was the mainstream standard for laptops and notebook computers.

In 2011, non-widescreen displays with 4:3 aspect ratios were only being manufactured in small quantities. According to Samsung, this was because the "Demand for the old "Square monitors" has decreased rapidly over the last couple of years," and "I predict that by the end of 2011, production on all 4:3 or similar panels will be halted due to a lack of demand."

The resolution for computer monitors has increased over time. From 280 × 192 during the late 1970s, to 1024 × 768 during the late 1990s. Since 2009, the most commonly sold resolution for computer monitors is 1920 × 1080, shared with the 1080p of HDTV.2560 × 1600 at 30 in (76 cm), excluding niche professional monitors. By 2015 most major display manufacturers had released 3840 × 2160 (4K UHD) displays, and the first 7680 × 4320 (8K) monitors had begun shipping.

Most modern monitors will switch to a power-saving mode if no video-input signal is received. This allows modern operating systems to turn off a monitor after a specified period of inactivity. This also extends the monitor"s service life. Some monitors will also switch themselves off after a time period on standby.

Most modern monitors have two different indicator light colors wherein if video-input signal was detected, the indicator light is green and when the monitor is in power-saving mode, the screen is black and the indicator light is orange. Some monitors have different indicator light colors and some monitors have blinking indicator light when in power-saving mode.

Many monitors have other accessories (or connections for them) integrated. This places standard ports within easy reach and eliminates the need for another separate hub, camera, microphone, or set of speakers. These monitors have advanced microprocessors which contain codec information, Windows interface drivers and other small software which help in proper functioning of these functions.

Monitors that feature an aspect ratio greater than 2:1 (for instance, 21:9 or 32:9, as opposed to the more common 16:9, which resolves to 1.77:1).Monitors with an aspect ratio greater than 3:1 are marketed as super ultrawide monitors. These are typically massive curved screens intended to replace a multi-monitor deployment.

These monitors use touching of the screen as an input method. Items can be selected or moved with a finger, and finger gestures may be used to convey commands. The screen will need frequent cleaning due to image degradation from fingerprints.

Some displays, especially newer flat panel monitors, replace the traditional anti-glare matte finish with a glossy one. This increases color saturation and sharpness but reflections from lights and windows are more visible. Anti-reflective coatings are sometimes applied to help reduce reflections, although this only partly mitigates the problem.

Most often using nominally flat-panel display technology such as LCD or OLED, a concave rather than convex curve is imparted, reducing geometric distortion, especially in extremely large and wide seamless desktop monitors intended for close viewing range.

Newer monitors are able to display a different image for each eye, often with the help of special glasses and polarizers, giving the perception of depth. An autostereoscopic screen can generate 3D images without headgear.

Raw monitors are raw framed LCD monitors, to install a monitor on a not so common place, ie, on the car door or you need it in the trunk. It is usually paired with a power adapter to have a versatile monitor for home or commercial use.

The Flat Display Mounting Interface (FDMI), also known as VESA Mounting Interface Standard (MIS) or colloquially as a VESA mount, is a family of standards defined by the Video Electronics Standards Association for mounting flat panel displays to stands or wall mounts.

A fixed rack mount monitor is mounted directly to the rack with the flat-panel or CRT visible at all times. The height of the unit is measured in rack units (RU) and 8U or 9U are most common to fit 17-inch or 19-inch screens. The front sides of the unit are provided with flanges to mount to the rack, providing appropriately spaced holes or slots for the rack mounting screws. A 19-inch diagonal screen is the largest size that will fit within the rails of a 19-inch rack. Larger flat-panels may be accommodated but are "mount-on-rack" and extend forward of the rack. There are smaller display units, typically used in broadcast environments, which fit multiple smaller screens side by side into one rack mount.

A stowable rack mount monitor is 1U, 2U or 3U high and is mounted on rack slides allowing the display to be folded down and the unit slid into the rack for storage as a drawer. The flat display is visible only when pulled out of the rack and deployed. These units may include only a display or may be equipped with a keyboard creating a KVM (Keyboard Video Monitor). Most common are systems with a single LCD but there are systems providing two or three displays in a single rack mount system.

A panel mount computer monitor is intended for mounting into a flat surface with the front of the display unit protruding just slightly. They may also be mounted to the rear of the panel. A flange is provided around the screen, sides, top and bottom, to allow mounting. This contrasts with a rack mount display where the flanges are only on the sides. The flanges will be provided with holes for thru-bolts or may have studs welded to the rear surface to secure the unit in the hole in the panel. Often a gasket is provided to provide a water-tight seal to the panel and the front of the screen will be sealed to the back of the front panel to prevent water and dirt contamination.

An open frame monitor provides the display and enough supporting structure to hold associated electronics and to minimally support the display. Provision will be made for attaching the unit to some external structure for support and protection. Open frame monitors are intended to be built into some other piece of equipment providing its own case. An arcade video game would be a good example with the display mounted inside the cabinet. There is usually an open frame display inside all end-use displays with the end-use display simply providing an attractive protective enclosure. Some rack mount monitor manufacturers will purchase desktop displays, take them apart, and discard the outer plastic parts, keeping the inner open-frame display for inclusion into their product.

Van Eck phreaking is the process of remotely displaying the contents of a CRT or LCD by detecting its electromagnetic emissions. It is named after Dutch computer researcher Wim van Eck, who in 1985 published the first paper on it, including proof of concept. Phreaking more generally is the process of exploiting telephone networks.

Masoud Ghodrati, Adam P. Morris, and Nicholas Seow Chiang Price (2015) The (un)suitability of modern liquid crystal displays (LCDs) for vision research. Frontiers in Psychology, 6:303.

Occasionally monitors are placed on top of the hard case or CPU. A monitor located at a high level is a source of discomfort and, in the long run, can cause musculoskeletal problems in the neck and shoulder area. At a workstation where the desk and chair heights are properly adjusted, the monitor should be placed at the same level as the keyboard. The fact that discomfort caused by a monitor which is too high (above the horizontal) is worse than one which is slightly too low (below an acceptable visual zone) should be kept in mind while arranging a monitor at any workstation.

When using a larger monitor (17", 19" or larger) or one that is oriented to the "portrait" position, make sure that the top of the screen is not at a level higher than the operator"s eye.

The Dell� E172FP is designed for a wide variety of users ranging from the home to corporate or financial trading environments. It utilizes a 17" Active Matrix TFT LCD that displays brilliant images with a maximum resolution up to 1280x1024 pixels. Its wider viewing angle allows users to view the screen from various positions without compromising image quality. High contrast ratio of this display generates sharper and crisper lines, while its fast response times provide superior clarity for moving images. Those who require exceptional quality and reliability at an affordable price will appreciate the value that the Dell E172FP provides. This product has been tested and validated on Dell� systems to ensure it will work with your computer. It is supported by Dell� Technical Support when used with a Dell system.

The screen size is measured diagonally, from ‘corner to corner.’ Common monitor sizes, in inches, are 15″, 17″, 19″, and 21″. In the case of CRT monitors, the diagonal measurement is taken from the outside edges of the display casing and, therefore, the active display area is actually a few inches lesser. In LCD monitors, the diagonal measurement is taken from the inside of the beveled edge. As a result, a 17″ LCD display is comparable to a 19″ CRT display[1] [Figure 1].

Screen sizes. In CRT monitors (A), the screen size is measured diagonally from the outside edges of the display casing. In LCD monitors (B), the screen size is measured diagonally from the inside of the beveled edges. Thus a 17-inch LCD display is comparable to a 19-inch CRT display. The CRT display includes 2 inches of casing, as well

This is the ratio of the width of a screen image to its height. The aspect ratio for most CRT monitors is 4:3. However, the trend today is in favor of flat screens and wide-screen LCD monitors with aspect ratios of 16:9 and, occasionally, even 16:10 or 15:9, are common today.[2]

Until recently, images in radiology were viewed in the landscape mode, a tradition set by the computer industry. This mode is clearly not optimal for use in diagnostic imaging.[3] LCD monitors, being lightweight and thin, can be easily turned around and placed in a portrait mode, which corresponds with the image format of radiology images. A 17 × 14 image is optimally viewed in the ‘portrait’ rather than ‘landscape’ mode. The ‘portrait’ mode is particularly useful for chest and skeletal radiography and for mammography [Figure 2].[4]

Landscape (A) versus portrait (B) mode. By virtue of being lightweight and thin, LCD monitors can be placed in a portrait mode that corresponds with the 17×14 format of images obtained in chest and skeletal radiography. Mammography images can be optimally viewed in the ‘portrait’ (B) rather than the ‘landscape’ mode (A), as shown here

Pixel or ‘picture element’ is the basic unit used for generating a video or computer picture and is measured in millimeters. In the CRT display screen, a pixel is the distance between phosphor dots, whereas in the LCD display screen it is the distance between cells of the same color. A dot pitch is essentially a dot with a given color and brightness value. A smaller dot pitch implies a sharper image, as there are more dots in an area of a given size. In computer monitors, the pixel numbers are dependent on the aspect ratio of the screen (its horizontal size compared to its vertical size) and the display size. Standard monitors with a 4:3 aspect ratio have a width of 1024 pixels and a height of 768 pixels. Widescreen display monitors with a 16:9 aspect ratio have a width of 1024 pixels and a height of 576 pixels.[1]

The resolution is calculated as the product of the number of pixels in the horizontal axis (rows) and the number in the vertical axis (columns) on a computer screen. Commonly available computer monitors have resolutions of 640 × 480, 800 × 600, or 1024 × 768.[3]

In a CRT monitor, the horizontal resolution is limited by bandwidth and spot size, while the vertical resolution is limited by line spacing and spot size.[5] In comparison, the resolution in an LCD monitor is determined by pixel pitch (the product of vertical and horizontal pixels)[5] and ranges commonly from 1 megapixel (MP) to 5 MP. With ongoing refinements in technology, high-resolution monitors with resolutions as high as 9 MP and higher have started becoming available.

In CRT monitors, the resolution can be changed to match the frequency emitted by the video signal. This advantageous feature is referred to as ‘multisync.’[6] LCD monitors, in contrast, have a fixed resolution, which is termed the native resolution.

In general, the number of available shades of gray in consumer displays is limited to 256 (8 bit). Medical displays need a much wider grayscale range so that they can render nearly every shade of gray; the latest medical monitors offer upto 4096 shades of gray (12 bit). It is well known that color display monitors have a poor grayscale response.[4]

With the availability of a variety of monitors in radiology, there is a need to ensure that different displays show the same image consistently and that too over a long period of time. An optimal grayscale response for monitors can be achieved by calibration of monitors according to the guidelines given in part 14 of the DICOM standard: the grayscale display function (GSDF).[7] The DICOM GSDF ‘specifies a standard relationship for the shades of gray.’[8] It recommends the use of calibration systems for measuring the monitor display"s white level, black level, and the shades of gray in between, with allowances for the ambient light. The use of lookup tables (LUTs) converts a particular display to a DICOM-standard display, thereby ensuring consistency.

The color bit depth is the number of bits used to describe the color of a single pixel. The bit depth of monochrome monitors is 2, i.e., it offers two colors. Moving up the scale, color graphics adapter (CGA) and enhanced graphics adapter (EGA) monitors have bit depths of 4 and 8, allowing 4 and 16 possible color combinations, respectively. Video graphics array (VGA) monitors have a bit depth of 16, which permits 256 color combinations. A high-color extended graphics array (XGA) monitor allows 65,536 colors due to its bit depth of 32. A true color super video graphics array (SVGA) has a bit depth of 64, which permits 16,777,216 colors.[9] Knowledge of color bit depth is useful when working with color Doppler as well as CT scan, and MRI images, where color-encoded functional imaging is displayed on color monitors.

In monitors, the term brightness refers to the ‘emitted luminous intensity on screen.’[10] It is measured in candela per square meter (cd/m2 or nits). A higher cd/m2 or nit value indicates a higher onscreen brightness.[10] Luminance is defined as the ‘absolute quantity of radiation emitted from a given source of visible electromagnetic radiation.’[10] Luminance ratio (LR), the ratio of maximum luminance to minimum luminance (Lmax / Lmin), is also important.

Let us first examine the luminance of viewboxes. Low-intensity viewboxes have luminance values of 1000–2000 cd/m2, while the luminance of high-intensity viewboxes is 2000–3000 cd/m2. The viewboxes for viewing mammograms have higher luminance, ranging from 3500 to 5000 cd/m2.[11] With regard to monitor displays, CRT monitors generally have a maximum phosphor luminance of about 450 cd/m2 and an LR of about 900:1. These values are higher in the case of LCD monitors, with a maximum luminance of about 1000 cd/m2 and an LR of about 1200:1.[5]

In the case of LCD displays, monochrome and color displays are available for the diagnostic viewing of medical images. When currently available monochrome and color LCD displays are compared, there are a few important differences. The native brightness and contrast of monochrome displays are higher than those of color LCD displays.[13]

The contrast ratio in CRT displays remains constant over a wide viewing angle.[4] In comparison, the contrast ratio in LCD displays drops rapidly from the maximum to about 10:1 for a viewing angle of 85°[4] [Figure 3]. It is therefore recommended that the person viewing an image on a monitor should be seated directly, perpendicularly in front of the monitor; a viewing angle close to 90° eliminates ‘off-angle’ viewing. On-axis viewing is considered acceptable with both CRT and LCD monitors, but off-axis distortions can occur with LCD monitors.[15]

The importance of the viewing angle. A CRT display shown directly in front of the viewer (A) and off-angle (B). An LCD display shown directly in front of the viewer (C) and off-angle (D). The contrast ratio in CRT displays remains constant over a wide viewing angle (B) unlike LCD displays (D) where it drops rapidly. An incorrect viewing angle for LCDs may make images dim or disappear or misrepresented with off-axis distortion, all of which can result in the missing of subtle lesions. A CRT monitor has a larger viewing angle that advantageously allows multiple users to review images simultaneously

In a CRT monitor, the electron beam hits phosphor-coated dots, causing pixels of an image to flicker. Individually, each pixel is hit 60–80 times a second.[16] Flicker is annoying to the human visual system.[1] It is avoided in a CRT monitor by an adequate refresh rate, denoted by the number of times a display monitor is illuminated. The refresh rate is measured in Hertz (Hz). A refresh rate of at least 70 Hz is necessary in case of diagnostic CRT monitors.[17] For larger CRT monitors a refresh rate of 85 or even higher may be needed. In case of LCD monitors, there is no flicker due to the slow response time.[1]

This term is specific for LCD monitors; it describes the amount of time taken for a pixel to change from active (black) to inactive (white).[18] It is measured in milliseconds, with a lower number implying faster transitions and fewer visible artifacts like the ‘ghosting’ effect when the image moves across the screen. In color LCDs, response rate denotes the speed with which the monitor"s pixels change colors.