calibration photometer for lcd monitors manufacturer

EIZO’s ColorEdge monitors with built-in calibration sensors are developed and manufactured entirely in-house. See how they achieve the color precision and consistent image display needed for creative fields.

In February 2021, four of EIZO’s lead innovators accepted an Academy Sci-Tech Award (Technical Achievement) for the ColorEdge CG Series monitors with built-in calibration sensors. EIZO was the first manufacturer in the world to bring a self-calibrating color precision solution to market in 2010, and continues to commit itself to providing highly precise and sophisticated imaging solutions made with dedication and care.

In September 2020, the ColorEdge PROMINENCE CG3146 HDR reference monitor was awarded the 2020 Hollywood Professional Association (HPA) Award for Engineering Excellence. As the first true HDR reference monitor in the world to be equipped with a built-in calibration sensor, it was recognized for its advanced technologies that put it at the forefront of innovation in creative visual solutions.

ColorEdge is a line of color management monitors developed specifically for addressing users in photography, film, broadcasting, printing, and other creative fields. For these industries, not only color fidelity, but display characteristics such as brightness, gamma, and uniformity across the screen need to be maintained so the final output content displays as intended in the target environment.

Each ColorEdge monitor undergoes rigorous quality control during production and is individually adjusted in-house using one of the color industry’s highest end, professional spectrophotometers. The human perception of color varies greatly depending on several factors such as ambient lighting, surrounding color, angle of observation, and individual optical variances. Using a high-quality sensor to adjust the monitors to meet certain color standards ensures consistency by minimizing the effect these variables have in the measurement results. EIZO’s factory uses sophisticated machinery in its production line to automatically carry out calibration for each monitor in a controlled environment. The sensor is placed directly over the monitor and red (R), green (G), and blue (B) gamma values are measured from 0 – 255. Then the monitor’s 16- or 24-bit LUT (look-up-table) is used to select the 256 most appropriate tones from trillions of perceivable colors to achieve the smoothest color gradations. This results in an image without deviated steps.

LCD monitors commonly exhibit fluctuations in brightness and chromaticity across the screen, which affects color precision. To counter this, EIZO also measures and adjust multiple points on each monitor to achieve stable brightness and chromaticity across the entire screen and correct deviations using its patented digital uniformity equalizer (DUE) technology. DUE controls the tone values pixel-by-pixel across the monitor for evenly distributed luminance.

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The Environics® Series 6123 Ozone Transfer Standard with Photometer is the ideal system for those looking for a standard for ozone monitoring and reporting programs. A sister unit to the S6103, the S6123 focuses on automatically performs zero, precision, span and multi-point calibrations using O3.

The S6103 is required if you wish to performs zero, precision, span and multi-point calibrations using O3 but also NO, NO2, SO2, CO, hydrocarbons and other gases of interest.

The 6123 meets or exceeds all U.S. Environmental Protection Agency requirements for a level 3 bench or transfer standard. It is exclusively for use with the internal ozone generator. For applications that require monitoring of external ozone sources, the Series 6103 or 6113 are required.

Are you looking for the highest level of on-screen color accuracy for all of your screens, including projectors? Then the i1Display Pro is the solution for you! It’s two user modes, Basic and Advanced, provide serious Color Perfectionists with the perfect combination of unrivaled color precision, speed, options and controls to fit any workflow. You’ll no longer risk spending hours at your monitor perfecting images or video only to find that the display was not accurately representing the digital files. Properly profiling and calibrating your displays ensures reduced editing time and a more realistic no-surprises representation of final output.

Top-of-the-line i1Profiler color management software offers the ultimate in flexibility and control. Basic mode offers a wizard driven interface with predefined options for the quickest path to professional on-screen color. Advanced mode offers user-defined options for more sophisticated profiling workflows to deliver the highest quality color results on monitors and projectors, as well as display testing and quality assurance tools.

Compensates for the ambient light surrounding your workspace with Ambient Light Smart Control. Since the intensity or amount of ambient light in your workspace affects the way you perceive color on your display, take advantage of i1Display Pro to automatically adjust your profile or simply notify you as ambient light conditions change. With the integrated Ambient Light Measurement, i1Display Pro automatically determines the optimum display luminance for comparing prints to your display.

Flare Correct™measures and adjusts your display profile for reduced contrast ratios caused by flare light (or glare) falling on the surface of the display. By accurately measuring your effective display contrast ratio, you’ll have an even more accurate display profile.

Intelligent Iterative Profiling,an adaptive technology,produces optimized results for maximum color accuracy on each unique display every time you profile.

Next generation i1Profiler software for calibrating and profiling all modern display and projector technologies including LED & Wide Gamut LCDs. Advanced user-defined controls support more sophisticated workflows.

Save time by re-using profile settings on multiple displays connected to the same computer or multiple computers within a workgroup. In addition, Automatic Display Control (ADC) adjusts display hardware for increased speed and fewer manual adjustments.

The included i1Profiler color management software offers the ultimate in flexibility and control. Its Basic mode offers a wizard driven interface with predefined options for the quickest path to professional on-screen color. The Advanced mode offers user-defined options for more sophisticated profiling workflows to deliver the highest quality color results on monitors and projectors, as well as display testing and quality assurance tools.  i1Display Pro profiling provides full support for NTSC, ITU-R-Rec.BT.709 and PAL SECAM broadcast video standards.

The LCD sensor analyzes color contrast and brightness in no time and with the highest accuracy. It also automates ambient light measurements in combination with Barco’s QAWeb for DIN 6868-157 software version. The optical system supports displays with all current and emerging backlight technologies, including LED.

The colorimeter’s intuitive and compact design makes it very easy to use with any Barco medical display. The Barco LCD sensor comes with a standard 2-year warranty.

Why do monitors do this? Well it used to be because of the physical properties of CRT displays, but now monitors are actually built to display in this fashion because they make the display look better (possibly a weber"s law kind of thing). In fact, PC makers and Apple typically set their monitors to have gammas and these are different! PC is typically set to 2.2 and Mac to 1.8.

So how do we undo the gamma? Well, when we calibrate the monitor we are trying to make it so that there is a linear relationship between the value we put in our computer programs and what the luminance of the display is. So, we measure the input-output relationship (like the one above) and then invert it so that we can be sure that incrementing values will linearly increment the monitor output. How does that work? Well, you need to know about the gamma table. In your computer display card there is a table that maps each value from 0 to 255 to a finer resolution value (typically in today"s computers this is a 10 bit value - though we are hoping that will change to have finer resolution and all the software and hardware will support that). So, when you tell the monitor to go to say 54, then the value is looked up in the table and would come out as some number, 643 for an arbitrary example. Then the display card uses that value to set the luminance of the monitor to a value between 0 and 1024 (assuming a 10 bit table). What we can now do is manipulate that gamma table so that you can insure that the input values from 0 to 255 will range from 0 to 1024 in such a way as to make sure that the output of the monitor is linear with respect to the input values.

Why is this important? If you care about contrast, for one, it is really important. If the monitor is not linearlized and you display a gray value of say 128 and you want to have equal increments of white and decrements of black to make a grating, you might set your values to sinusoidally change from, say 64 - 128 - 192. But, this would not result in equally bright whites as blacks are dark because of the gamma relationship between these input values and output luminance. You would have an overall change in the luminance of the patch as you change contrast. This would not be good. So, we calibrate monitors.

Our code may work with different models, but we have only tested the above listed models. If you want to use another photometer you can input the readings manually or consider writing a few lines of code in moncalib to support your photometer type.

Note that there are some commercially available devices to calibrate monitor screens which create color profiling information. We have tested one of these called Spyder2Pro which allows you to linearize the monitor output but found that is not yet suitable for psychophysics purposes. The calibration program crashes when you use the default settings to linearize the monitor (an email to the tech support confirmed this is a bug in their software). Using advanced settings it worked but it could only test luminance at 5 output levels. The linearization that it achieved was not accurate enough when tested with the PR650 (it looked like they are doing some sort of spline fit of the points and the luminance as a function of monitor output level looked like a wavy line around the ideal).

You will also need an adaptor to connect the USB on your computer to the photometer. Make sure you have a good device - cause this is typically the reason why you might have a problem connecting to your photometer. Some work, some don"t. Some break when you upgrade your OS. Why? Because they rely on driver software that the developers don"t really spend so much time making sure works perfectly. That is, they are buggy. So, if things don"t work, it is very likely that you don"t have a good USB/Serial device driver. Here is what we know has worked for us and what has not.

Typically you can just connect the USB/Serial device to the Serial cable of the photometer, but for the Topcon you will need a nullmodem connector between the two (this swaps the read/write lines for communication). It looks like this (remember this should only be necessary for Topcon).

any Randeon card for desktop computers above series 7000 has 10-bits DAC resolution (laptop cards don"t have it necessarely or drivers do not access it)

Make sure the device driver for your particular usb/serial device is installed. Also, make sure that mgl is updated. After the installation is complete you need to restart the computer.

Run moncalib in the commTest mode. Run and choose your photometer (the below demonstrates with Minolta and the Keyspan USA-19HS USB/Serial device)>> moncalib("commTest=1")

You will be asked to turn on your photometer and make sure it is in the correct mode (you should have already done this):Please turn on the LS100 and press the white F key at the same time.

It will try to make a measurement. If all is good, it should report no errors and give you a luminance value that looks reasonable (make sure you are pointing at something reasonably bright). Looks like this (moncalib:photometerTest) Trying to make a measurement from your photometer.

4) Check to make sure you have the correct cable (For example, the Topcon needs a null-modem cable that crosses read/write lines, while other photometers may need a simple pass through cable).

5) Make sure that your communication mode on the device is setup correctly. Minolta can only use 4800/even/7 bits/2 stop bits. Other photometers have different settings, but should be set to 9600/none/8/1

Each photometer is a bit different in how you get it setup for serial mode. The section below describes the procedure for each of the photometers we have worked with.

First make sure that the topcon has the correct serial port settings, by pushing the [MODE] key for about 2 seconds to enter the function mode. Then push the [ENTER] key four times to set the RS-232C Parameters. The settings should be Baud rate: 9600, Length=8, parity=NONE, Stop bit=1. Use the [CHANGE],[ROTATION] & [ENTER] keys accordingly.

When using the automated calibration via the serial port, the program will ask you to turn on the PR650 and then press "return" within 5 secs. You might not want to press "return" right away, or you may get something like this on the photometer:

This indicates that you pressed the return while the photometer is waiting for a transfer signal (not sure what it is), and hence entered the XFER mode. If you wait another 2 secs or so it will enter the control mode, now press "return" you should see this:

When doing the automated calibration, turn off screensavers and energysaver, otherwise the screen will go blank after a while and you"ll be measuring luminance of blank sreens.

If you cannot install the serial port interface or don"t want to automatically calibrate using the USB cable you can also use the program to run manually with any photometer by typing in the luminance measurements yourself.

You can just run as follows (the directions are similar to when you tested the comm port above) Note that we also set initWaitTime so that you have 60 seconds before the calibration starts to turn off the lights and leave the room.moncalib("initWaitTime=60");

When you have run the calibration, try running mglEditScreenParams, select “Find latest calibration” for the calibType and click the displayCalib button to see your calibration. If your calibration does not show up there, then it will not be used when you run your stimulus programs, so it is important to confirm. You will also see text that will describe your calibration, like the following(moncalib) Displaying data for calibration file /Users/steeve/proj/mgl/task/displays/0001_sr14-3fa8fef553_141110

tableTest1After getting calibration, tests that calibration by putting the inverse table into the gamma table and running through values. Should give a nice linear relationship between input and output

The program moncalib will save a calibration file in the local directory. For you to use this calibration file, you can store it in one of two places. Either in your own program directory under a directory called displays:

InitScreen should automatically find the correct table by checking your computer name and looking for the file in these two places. If you do not use the standard filename, or have multiple calibrations for the same computer (like if you have multiple monitors calibrated), you can use a specific file by setting myscreen.calibFilename

Where xxxx is a sequential number starting at 0001 and yymmdd is the date of the calibration. This stores a variable called calib which contains all the information about the calibration. You can quickly plot the data in calib by doing:

SMfit ACT software package calibrates monochrome displays using internal sensor in company"s monitor or serial photometer. It also calibrates color CRT monitors and LCD displays via Universal Luminescence Meter. Software can check local and remote displays, automatically adjusting luminance settings and gamma functions, and compensate for geometry and focus. Integral scheduler automatically performs checks at programmable intervals.

Siemens Automation and Drives (A&D) has extended the hardware and software of the calibration tools for its high-resolution displays used in medical imaging applications. The new SMfit ACT (automatic calibration tool) software package is available in two versions. In addition to monochrome displays, SMfit ACT Calibration now also calibrates color CRT monitors and color LCD displays (flat screens). For this purpose a universal photometer has been developed. The new SMfit ACT Remote software checks even remotely installed displays without the need for a service engineer on site.

Displays and monitors in medical imaging applications are regularly checked with calibration tools to ensure consistent quality. Quality control is an important prerequisite which facilitates accurate diagnoses by the examining doctor.

The new SMfit Calibration tool uses an internal sensor in the Siemens monitor or a serial photometer, such as the Siemens Spot Meter for monochrome CRT or LCD displays. Using the new Universal Luminescence Meter it is now also possible to calibrate color CRTs and LCDs. The conformance check of SMfit Calibration corresponds to the international DICOM standard (digital imaging and communications in medicine) and the DIN constancy test. In addition, luminance settings and gamma functions are automatically adjusted and the geometry and focus are compensated.

The new SMfit ACT Remote software also activates conformance checks for remotely-installed displays. The main areas of application are hospitals, where medical monitors are distributed among a large number of "reading rooms" and linked by a network. The test results and reports are available not only on the locally installed display, but also on the remote service computer. As the service engineer does not have to visit the individual monitors, valuable time is saved. An integral scheduler automatically performs checks at programmable intervals, clears certain faults in the consistency of the display or notifies the service engineer via e-mail or a pop-up message.

provides a true 14 bit monochromatic output. Note that the Bits++ device is now deprecated and has been replaced by the Bits# device. For more information, see the Video Outputs section of the chapter Supported External Devices.

horizontal resolution. Note that the Bits++ device is now deprecated and has been replaced by the Bits# device. For more information, see the Video Outputs section of the chapter Supported External Devices.

This mode provides a quasi-continuous resolution for luminance and color outputs by using a stochastic dithering technique (Allard & Faubert 2008) without losing much spatial resolution.

In SpectraView, de-select the "Calibration On" checkbox. You can also check your user manual for directions to unlock the controls without using SpectraView.

The SVII-KIT has been discontinued as of February 2009 and has been replaced with the SVII-PRO-KIT. All LCD3090W-BK-SV (LCD3090WQXi SpectraView bundle), LCD2490W2-BK-SV (LCD2490WUXi2 SpectraView bundle), LCD2690W2-BK-SV (LCD2690WUXi2 SpectraView bundle), P221W-BK-SV (P221W SpectraView bundle) include the new SVII-PRO-KIT with the new MDSVSENSOR2. Other bundle models created before February 2009 may include the SVII-KIT, but all bundle models created after this date include the new SVII-PRO-KIT.

The -SV series are the bundles of a display monitor with the SVII-PRO-KIT (color sensor and SpectraViewII software). The naming consists of the monitor model name (LCD2690W2 is an LCD2690WUXi2), followed by "-BK" to indicate the color is black (for models available in colors other than black). Lastly the "-SV" indicates it is the SpectraViewII series bundle.

Yes. Free updates are available for download for customers who have purchased SpectraView. The license key from your original purchase will be required to install and use the software.

Unfortunately no. Before purchasing please be sure to carefully check the latest compatibility information for your system in the README file for the latest version of SpectraView.

For detailed questions regarding SpectraView please use the online feedback form. Support is also available for SpectraView and all other issues by contacting NEC.

The number of letters visible will depend on the calibration settings and viewing environment. In some cases it may be very difficult to make out the "...NTROL", especially with high levels of ambient light.

See the User"s Guide and README file included with the software and on the NEC website for further information about any specific incompatibilities or issues.

2) Confirm that your model of display monitor is supported by SpectraView. See the README file included with the latest version for a complete list of supported models.

Why are the Spyder color sensors not recommended for use with wide color gamut displays such as the LCD2690WUXi, LCD2690WUXi2, LCD3090WQXi, P221W, PA241W, PA271W and PA301W models?

Our evaluation of these devices has determined that the accuracy of measurements when used with wide color gamut displays could lead to large color errors. Therefore we do not recommend using this device on wide color gamut displays.

Spectraview software is specifically designed to work hand in hand with NEC Displays. The software works seamlessly with a compatible display and supported calibrator for color-critical applications, such as photography, video editing, animation and medical imaging. Using our software will ensure you"re getting the most out of your display.

No. The hoods for many models are available as a separate option in the accessories section, or can be purchased from online retailers who sell NEC Professional displays. The part number for the hoods are listed on the corresponding display product page.

Yes. Starting with SpectraView version 1.1.00 all Target files are cross platform between Mac, Windows, and Linux. This means it"s possible to send Target files to other users on different machines.

If you are using analog (VGa or DVI-a) video then this is not recommended because there can be variances between the analog video signal levels on different machines that can impact the calibration.

When used with the SpectraView software, NEC display monitors store all of the necessary color adjustments internally, including the 10- or 12-bit Look Up Tables. The ColorSync utility switches the display color settings by changing the Look Up Tables in the video graphics adapter. The ColorSync profiles generated by SpectraView contain linear Look Up Tables for the video graphics adapter. Because of this, SpectraView must be used to update the display monitor.

No. SpectraView will automatically regenerate the correct ICC/ColorSync profile for the current calibrated Target settings and install it on your system.

No. SpectraView is targeted specifically at providing the best possible color performance and calibration with the supported NEC displays using hardware calibration. Other displays can be profiled but not calibrated in SpectraView.

For Delta-E values of less than 2 there is almost certainly no need to recalibrate. For values higher than 3 it is important to understand what the cause is and whether it"s significant.

The calibration and adjustment process has inherent variability due to many factors such as the repeatability of color sensor measurements, and changes within the display as it is adjusted. The basic accuracy and repeatability specifications for most sensors are +/- 0.002 or higher for CIE xy, and +/- 2% for luminance. These variances alone can give rise to Delta-E values of up to 2 or 3.

When a specific Intensity value is being used for the calibration, the Delta-E value is comprised of the luminance and color differences. Differences in color are much more critical than a difference in relative luminance. Look at the results of the calibration shown in the Information window to determine if the high Delta-E value is caused mainly by a shift in color or in luminance.

High Delta-E values can also occur if a specific Intensity value is being used for the calibration and the display is not capable of achieving the specified Intensity value. The calibration will always aim to achieve the specified White Point, even if the Intensity value could not be reached. If the display can not be calibrated to achieve the specified Intensity value modify the value accordingly.

In some situations, the display Intensity will drift slightly for several minutes after it is adjusted. Since the measured value used to calculate the final Delta-E result is taken up to one or two minutes after the display was adjusted, a higher Delta-E value may be shown, even though the calibration process achieved the specified Target values during the calibration process. Selecting the Extended luminance stabilization time option in the Preferences can be used to try and minimize this effect.

The Delta-E result values shown in SpectraView are higher than those shown in other display calibration applications. Does that mean they are better at calibrating the display than SpectraView?

No. SpectraView calculates the Delta-E values using both the luminance and color differences for more realistic and accurate values. Other applications may calculate Delta-E differently.

After calibration I manually adjusted some of the monitor controls to get a better color match for my particular application. What happens the next time I calibrate the monitor?

The manual adjustments will be reset by the calibration process. We recommend that you avoid manually adjusting the monitor after calibration for this reason.

If you feel it is necessary to tweak the display after calibration, create a new Target file based from the measurements of the display after it has been manually adjusted. Then the monitor will be automatically calibrated to that particular set of characteristics the next time it"s calibrated. Use the Custom White Point tool to measure and set the white point and Intensity values.

These graphs will only show data when the monitor is calibrated to a Target that uses the DICOM response curve. DICOM is normally only used for medical imaging applications.

SpectraView will automatically install the device drivers for the iOne Display color sensor. However it is assumed that if you are using a third-party sensor, then the software that came with it will have already installed the drivers for the device. If you did not install the third-party software then the device drivers will need to be manually installed.

Drivers for all sensors are available on the SpectraViewII CD-ROM or in the \Program Files\Sharp NEC Display Solutions\SpectraViewII\Drivers folder after installing SpectraView (on 64 bit versions of Windows the folder location is \Program Files (x86)\Sharp NEC Display Solutions\SpectraViewII\Drivers).

Yes. The "in the box" video drivers included with Windows 7 do not contain the necessary support for communicating with the display monitor that SpectraView relies on. If you receive a "No communications" error, obtain and install the full drivers directly from the video graphics adapter vendor.

Unfortunately in some cases it may not be possible to calibrate the display directly using SpectraView due to compatibility issues with certain versions of Mac OS or Mac hardware. Such issues are normally out of our control, but we are always working closely with apple to resolve these kinds of issues as soon as possible. In the interim time, the following solutions may be considered:

1) If possible, calibrate the display on another Mac or PC that is supported. Since the display is hardware calibrated it can be moved to another machine and the calibration will remain valid. Be sure to also copy and associate the ColorSync profile of the display.

4) Calibrate using a non-hardware based 3rd party calibration package. Such software may have been included with your color sensor or available from the manufacturer"s website.

I would like to share the calibration results and graphs in SpectraView. Is there an easy way to access this information or make screenshots of the graphs?

Yes. In the "Information" window, right click within any of the tabs and select "Copy." This will either copy the graph as an image, or calibration information as text, into the clipboard. This can then be pasted into other applications.

In general a spectrophotometer provides more accurate color measurements than a "generic" colorimeter does when measuring most displays. However a colorimeter can be specifically calibrated against a lab grade instrument to match a particular type of display, and thus provide extremely accurate color measurements. This approach was taken with the new custom-calibrated X-Rite iOne Display V2 included in the Display Calibration Bundle.

A spectrophotometer can suffer from drift and low luminance noise issues that can cause problems—specifically when measuring and calibrating near black. In general colorimeters provide superior low luminance measurements than spectrophotometer.

The LCD panels used in the SpectraView displays have excellent color linearity characteristics and can be characterized using the much simpler shaper/matrix profiles. accurate 3D LUT profiles require a minimum of around one hundred measurements (and up to several hundred) to generate the necessary data and offer very little advantage despite the large increase in measurement time. additionally there are some compatibility issues with various software applications when using 3D LUT type display profiles.

At this time SpectraViewII is only available for purchase within the US and Canada. In Europe please contact your regional NEC sales office for information on what calibration options are available. In Japan SpectraViewII is sold under the SpectraNavi name.

Yes. The SpectraViewII calibration system is developed by NEC and optionally includes an NEC branded X-Rite iOne Display V2 color sensor. SpectraViewII can be used with any supported display model and is sold both as a complete kit bundled with a display, and as an add-on product.

In Europe SpectraView Profiler includes a display monitor with hood, custom calibration software developed by basICColor, and each display is individually certified. It is not possible to purchase and use the SpectraView Profiler software with a non-SpectraView Profiler display.

The new SVII-PRO-KIT includes the MDSVSENSOR2, an NEC branded X-Rite iOne Display V2 color sensor that is custom calibrated for increased measurement accuracy with our wide color gamut displays such as the LCD2690WUXi, LCD2690WUXi2, LCD3090WQXi, and P221W. It is backward-compatible with standard color gamut displays. The SVII-KIT included an NEC branded X-Rite iOne Display V2 but did not have any custom calibration.

I have two supported NEC display monitors that I would like to use in a dual monitor configuration on one machine. Do I need to buy two SpectraView licenses?

Yes, but it is currently limited to customers with large installations of NEC display monitors. To learn more, please submit a request using the online feedback form.

The most advanced, innovative and user friendly digital aerosol photometer available today, the 2i Digital Photometer is portable, yet rugged, and the ideal instrument for in-situ filtration system integrity testing. The iProbe, a handheld scanner with local LCD display and controls, enables the operator to change settings without stopping to adjust the base unit, minimizing downtime.

The 2i base instrument’s 4.3 in. LCD gives life to the easy to use, menu driven interface. Aerosol measurements and pump sampling rates are prominently displayed for easy viewing. System parameters and selections such as alarm types, alarm set points and aerosol reagent are shown on the lower menu bar, while icons at the top of the screen give the status of connected peripherals, reporting functions, and aerosol noise suppression selections.

Annual NIST traceable calibration service is provided by ATI or an ATI-certified calibration facility. Calibration includes setting the aerosol reagent references, sample flow reference points, operating voltages, and servicing the light scattering chamber assembly. Routine preventative maintenance entails cleaning and inspection of internal sample tubing and connections, the internal reference filter, and iProbe.

Designed for the rigors of nuclear and other hazardous applications, the 2i-N (the nuclear version of the 2i) is equipped with a unique, sealed sample train. The unit is engineered to allow safe removal and replacement of contaminated sampling components.

Upstream aerosol mass concentrations are displayed in actual mass concentration values of micrograms per liter (μg/l). User settable Aerosol Noise Suppression (ANS) allows for more stable aerosol.

Image quality assurance has traditionally been a high priority in medical imaging departments. Recently, it has often been neglected with the transition from hard copy (film) to soft copy (computer) display systems, which could potentially result in difficulty in reading images or even misdiagnosis. This transition therefore requires careful management such that comparable image quality is achieved at a minimum. It is particularly difficult to maintain appropriate image quality in the clinical settings outside of medical imaging departments because of the volume of display systems and the financial restraints that prohibit the widespread use of dedicated computers and high-quality monitors. In this study, a protocol to test and calibrate display systems was developed and validated by using an inexpensive calibration tool. Using this protocol, monitors were identified in a hospital in which image quality was found to be inadequate for medical image viewing. It was also found that most monitors could achieve a substantial increase in image quality after calibration. For example, the 0 and 5% luminance difference was discernable on 30% of the piloted display systems before calibration, but it was discernable on 100% post calibration. In addition, about 50% of the piloted display systems did not have the maximum luminance (white level) suitably set, and 35% of them did not have the minimum luminance (dark level) suitably set. The results indicate that medical display systems must be carefully selected and strictly monitored, maintained, and calibrated to ensure adequate image quality.

Key words:Image quality, display system, calibration, quality control, quality assurance, monitor, medical imaging, softcopy, cathode ray tube, liquid crystal display, DICOM 14, Grayscale Standard Display Function, SMPTE, luminance

Although the quality of medical images (digital or otherwise) is strictly controlled during acquisition, it is often poorly maintained for soft-copy image review. Image quality control of softcopy display systems is often neglected because it can be an expensive and complex process to ensure. Most health institutions cannot afford to standardize on high-end medical display systems, but instead have a mix of various types

This article discusses and demonstrates the importance of maintaining image quality of soft-copy display systems, the development of a calibration protocol, and recommendations on how to achieve image quality control.

Display systems should be cleaned regularly with monitor cleaner to remove fingerprints and other stains. There are many different types of commercial monitor cleaners, including sprays (to be sprayed on a soft cloth before application), individual wipes, and boxed wipes. Cleaning solutions can vary from being polymer-based to a solution of 50% water and 50% isopropyl. Care should be taken not to use alcohol-based or ammonia-based cleaners because it could permanently damage the screen surface (e.g., turning LCD screens yellow and brittle, or damaging CRT monitor antiglare coatings).

The minimum luminance (dark level) must first be properly set by changing the “brightness setting.” Ideally, monochrome CRT monitors can be set between 0.2 and 0.5 cd/m2. Monochrome LCD monitors can usually be set at about 1.0 cd/m2. The lower the dark level the better, but at the same time, the monitor must be able to provide a maximum luminance adequate for the particular application (e.g., 170 cd/m2 for most images displayed on color monitors, and 350 cd/m2 for most images displayed on monochrome monitors).

The maximum luminance should be set by changing the “contrast setting.” The optimal value for this setting will depend on several factors. If there is a high level of ambient lighting in the room, then a higher maximum luminance will be required to give the same image quality that is required in a darker area. If the maximum luminance, however, is set too high for a particular monitor, it will significantly shorten its useful life span. The ambient lighting should therefore be minimized if at all possible. For new monochrome monitors, the optimal scenario to prolong their useful life span would be to drive the monitor at 50% of its capable maximum luminance to achieve 300–350 cd/m2. New color monitors should be driven at about 70% of their capable maximum luminance (about 250 cd/m2) to achieve about 170 cd/m2.

To ensure that as much information as possible can be seen by the human eye, display systems should be set to the Digital Imaging and Communications in Medicine (DICOM) 14 Grayscale Standard Display Function (GSDF) (see Fig 1). This is necessary because the response of the human eye to light is not linear. This step is achieved by mapping bit values representing different gray levels to specific luminance values. The mapping is stored in look-up tables (LUT) on the graphics card or in the monitors.

DICOM 14 Grayscale Standard Display Function (GSDF). The Just Noticeable Difference (JND) index is the minimum amount that the luminance can be changed for the human eye to perceive a difference.

The final step is a visual check. There are several geometric patterns and patterns of varying luminosity that can be helpful. One that is often used is the Society of Motion Picture and Television Engineers (SMPTE) pattern (see Fig 2). This pattern can be used to detect areas that are unfocused (horizontal and vertical thin lines that should be discernable) and to determine the proper contrast (especially the 0 to 5% luminance difference and the 95 to 100% luminance difference). The SMPTE pattern can also be used to align the window vertically and horizontally and to determine if there is skewing or bowing (pincushion effect). Other parameters to check include ghosting (i.e., when previous images linger), burn-in on CRT monitors, pixel dropout in LCD monitors, and nonuniformity of luminance (see Fig 3). Uniformity of luminance can be measured by placing the photometer on different quadrants of the monitor. Luminance nonuniformity is usually not a problem with LCD monitors, but can be a problem with CRT monitors. This can occur if the CRT phosphor coating is not applied evenly, if the phosphor on the edges of the screen gets less light than in the middle of screen due to the distorted electron beam, or if there is a misalignment in the CRT components. Nonuniformity is also prevalent in CRT monitors that are within a magnetic field.

A variety of clinical and radiological Picture Archiving and Communication Systems (PACS) workstations from a multisite teaching hospital were identified for use in a pilot study for the protocol. The purpose of the pilot study was (1) to determine the value of a monitor quality control program through an assessment of their current state and noting any improvements after application of the protocol, (2) to validate and if necessary, to modify the protocol, and (3) to determine the resource requirements to perform the quality control program.

Sixteen PACS workstations (11 dual-monitor systems and 5 single-monitor systems) were calibrated during the study. Three of the workstations were intentionally included for the pilot due to complaints of poor image quality, whereas the other workstations were randomly chosen out of approximately 1,000 workstations that are used for viewing medical images. They were selected from radiology reading rooms and clinics to represent a range of monitor types.

Four monitors out of the 27 monitors tested were found to be inadequate for medical image review even after calibration. The monitors were inadequate because either the maximum luminance for these monitors were about 90 cd/m2, which was much lower than the ideal maximum luminance of 170 cd/m2 for color monitors, or the monitors were visibly unfocused. In addition, the calibration photometer was not able to connect to two workstations, which had computers that were nonstandard to the hospital and were not supported by the hospital IT department. Both of the workstations had monitor quality deemed inadequate for image review and have been excluded from the following results summary.

Most monitors showed significant image quality improvements from calibration (Fig 4). Before calibration to the GSDF, on approximately 70% of the monitors, the difference between 0 and 5% luminance could not be seen on the SMPTE pattern. After calibration, this difference was discernible on all the monitors. The maximum luminance and dark levels were often adjusted to prolong longevity of the monitors while trying to optimize image quality. Other image-quality-degrading factors that were found include areas that are unfocused, phosphor burn-in from a static image (hospital logo used as the Windows desktop wallpaper) left on the monitor too long, incorrectly set aspect ratios, and dirty screens.

Image quality improvements through calibration. 1, Monitors able to discern between 0 and 5% luminance values; 2, monitors able to discern between 95 and 100% luminance values; 3, monitors with maximum luminance not optimally set (difference between calibrated and original values >10 cd/m2); 4, monitors with dark levels not optimally set (difference between calibrated and original values >0.2 cd/m2).

It took on average 30 min to calibrate a display system by a trained technician with limited experience performing the protocol. An experienced technician could calibrate a display system in about 15 min.

Initial calibration and periodic testing of PACS monitors are important for maintenance of image quality. A degradation of image quality over a long time is often difficult for clinicians to detect. This can result in a delay in reporting of problems until the viewing of the images is severely degraded by the display.

The frequency of calibration and testing can vary greatly. Hospitals have performed weekly, quarterly, or even daily monitor tests, whereas others do not calibrate monitors at all.

In addition to the methods described above, the following are other means to facilitate the maintenance of image quality:The use of a maintenance database to record calibration results, age, warranty, location, etc. of the PACS monitors would provide several benefits. For example, it would allow a convenient method of scheduling monitor maintenance.

Disabling user control of the display settings and training the users to modify window and leveling in the PACS viewer application instead of changing the monitor contrast and brightness will also help reduce the frequency of required calibration.

Procedures for escalation and maintenance of PACS display systems should be streamlined. This would include clarifying who is first-line support and having backup hardware on-site.

Environmental factors, such as ambient room lighting, glare, and placement of the monitor ateye level, should also be considered for optimizing medical image viewing.,

Precalibration, clinicians had complained about the inadequate image quality of some of the monitors that were calibrated for this study. After calibration or replacement of the monitors, the clinicians no longer complained about the image quality. This suggests that the clinicians did notice the postcalibration improvements. An in-depth investigation into the clinical perception of the image quality improvements from calibration was outside the scope of this study.

Adding to the complexity of ensuring adequate image quality is choosing the proper supporting hardware (monitors, computers, and graphics cards). Although standardizing on a single vendor of PACS hardware can assist in the maintenance of the equipment, it is often difficult to achieve in practice because of financial constraints and/or the need to select different monitors for different applications. Space requirements might dictate theuse of an LCD monitor instead of the larger CRT monitor. The once prohibitively high cost of high-bright grayscale LCD monitors is becoming less of a problem as the cost of LCD monitors continually drop, whereas concurrently, the advancements in LCD technology lead to increasingly better image quality.

CRT and LCD monitors have their own strengths and weaknesses, but more institutions are moving from using CRT monitors to LCD monitors. Table 1 summarizes their characteristics.

The type of images that will be viewed on the PACS workstation will also influence the monitor selection and computer configuration. Here are some questions that need to be asked when developing a display system.Are the images monochrome or in color? The trade-off of color monitors is that they cannot achieve the level of luminance of grayscale monitors.

Are the images high-resolution and high-contrast (e.g., computed radiography) or low-resolution and low-contrast (e.g., magnetic resonance imaging) images? This will determine the required monitor resolution and the suitability of using grayscale monitors.

Is the display system going to be used for primary diagnosis or for a clinical review? Are the structures that need to be identified gross structures (e.g., metal leads that were inserted into the body) or small, hard to discern structures (e.g., in mammography images)? This will influence several decisions regarding hardware selection, including the required bit depth of the graphics card. Most graphics cards are 8-bit digital to analog converters (DAC) allowing 256 levels of intensity for each red, green, and blue channel, but often higher-bit depth cards are preferable (10-bit cards) for monochrome monitors.

Will past and current images of the same patient need to be compared side by side? Will multiple views of the anatomy need to be viewed simultaneously? If so, then dual monitors will likely be required. In this case, care must be taken in choosing a graphics card that has two LUTs so that both monitors can be calibrated to the DICOM GSDF. Most graphics cards, especially the less expensive ones, do not have dual LUTs, which means that only one monitor can be calibrated.

It is also beneficial to obtain clinical feedback on the type of PACS workstation hardware that will be put into a particular unit. Unfortunately, this is often not done due to time constraints or lack of available hardware. Whenever possible, demo units should be trialed to obtain clinical feedback before the hardware is purchased. This should be done for several days to give all the staff adequate opportunity to use the equipment and to provide verbal or written feedback on a survey form.

Several medical display manufacturers are starting to develop methods to help achieve and maintain stable image quality. Many high-end monitors are now strictly factory-calibrated for medical viewing. There are also LCD monitors available that do periodic self-calibration with an internal backlight sensor or with a permanent photometer on the corner of the monitor. Unfortunately, these are usually very expensive high-end monitors.

Remote calibration is also emerging as an option, whereby PACS workstations are connected to a main administrative computer. The main administrative computer receives alerts of monitor drift that cannot be compensated, and it can trigger the computers to do self-calibrations. Remote calibration, however, has some of the same problems as the self-calibration monitors. Presently, remote calibration requires all of the monitors to be of a single brand. Standardizing onto a single high-end monitor brand would be prohibitively costly and impractical for most institutions.

The proliferation of PACS has permitted the softcopy review of medical images outside, as well as within, the radiology department. Although the selection of proper display system hardware will vary depending on the application and the environment, maintaining proper image quality should always be a consideration for the system"s ongoing use. This is often a difficult program to establish and maintain due to limited human and financial resources, the large number of display systems that are often nondedicated standard desktop computers and monitors, and the lack of comprehensive standards.

It has been shown through the pilot of a monitor quality assurance protocol that a proactive calibration program can ensure adequate image quality. An inexpensive method of monitor calibration has been described that can be applied to any type of monitor. Substantial image quality improvements were seen postcalibration, and monitors that were no longer adequate for medical image display were identified and replaced. The use of an image quality maintenance protocol will lead to more efficient image review and more accurate diagnoses.

7. Wang J, Peng Q. An interactive method of assessing the characteristics of softcopy display using observer performance tests. J Digit Imaging.2002;15(Suppl 1):216–218. doi: 10.1007/s10278-002-5003-3. [PubMed] [CrossRef]

8. Wang J, Compton K, Peng Q. Proposal of a quality-index or metric for soft copy display systems: contrast sensitivity study. J Digit Imaging.2003;16(2):185–202. doi: 10.1007/s10278-003-1657-8. PubMed] [CrossRef]

9. American Association of Physicists in Medicine (AAPM), Task Group 18. Assessment of Display Performance for Medical Imaging Systems: Pre-final Draft (Version 8.1), February 2002

10. Gray JE, Lisk KG, Haddick DH, Harshbarger JH, Oosterhof A, Schwenker R. Test pattern for video displays and hard-copy cameras. Radiology.1985;154:519–527. [PubMed]

12. Parsons DM, Kim Y, Haynor DR. Quality control of cathode-ray tube monitors for medical imaging using a simple photometer. J Digit Imaging.1995;8(1):10–20. [PubMed]

13. Chakrabarti K, Kaczmarek RV, Thomas JA, Romanyukha A. Effect of room illuminance on monitor black level luminance and monitor calibration. J Digit Imaging.2003;16(4):350–355. doi: 10.1007/s10278-003-1720-5. PubMed] [CrossRef]

14. Ratib O, Amato C, Balbona JA, Boots K, McCoy JM. Design and implementation of a multi-task radiology workstation ergonomically tailored for fully digital reading rooms. Proc SPIE.2001;4323:93–96. doi: 10.1117/12.435461. [CrossRef]

15. Blume H, Ho AMK, Stevens F, Steven PM. Practical aspects of greyscale calibration of display systems. Proc SPIE.2001;4323:28–41. doi: 10.1117/12.435509. [CrossRef]

Leading the industry in real-time dust monitoring, the DustTrak™ DRX Aerosol Monitor 8533 can simultaneously measure both mass and size fraction. The DustTrak DRX desktop monitor is a multi-channel, battery-operated, data-logging, light-scattering laser photometer that gives you real-time aerosol mass readings and collects a gravimetric sample. It uses a sheath air system that isolates the aerosol in the optics chamber to keep the optics clean for improved reliability and low maintenance.

It is suitable for clean office settings as well as harsh industrial workplaces, construction and environmental sites, and other outdoor applications. The DustTrak DRX monitor measures aerosol contaminants such as dust, smoke, fumes and mists.

No matter how perfectly a monitor was calibrated at the factory - it still needs to be recalibrated at regular intervals. This must be done to correct the unavoidable ageing processes of the panel,and to calibrate individual targets suitable for the application andlighting conditions at the workplace.

An external attachment sensor is usually used for this purpose, which always involves extra effort. The user must remember to recalibrate and take the time to interrupt their actual work and perform the calibration process. With a built-in calibration sensor, this process can be automated and moved to a time when the monitor is not in use.

So with CG Series ColorEdge monitors, you can arrange for the monitor to recalibrate itself periodically (e.g. at night) when you"re not using it. This means you can always be sure you are working with a consistently accurate monitor.

The advantages of CG Series monitors with their built-in calibration sensors are even greater in companies with numerous monitors: In combination with ColorNavigator and the cloud solution ColorNavigator Network, EIZO offers a complete colour management solution whichmakes it possible to realise complete quality assurance including regular recalibration, the distribution of calibration targets and the control of numerous monitor functions centrally and across locations.

Even if a ColorEdge monitor is delivered perfectly adjusted and calibrated, regular recalibration is necessary. The built-in calibration sensor can be used to automate this recalibration. As a user, you can schedule thisvital procedure for times when the monitor is not in use. The monitor menu or the ColorNavigator can be used to determine when the monitor should calibrate itself. This can be done either at fixed intervals or depending on the time of use. Of course, this calibration does not interrupt the user"s work, but only takes place the next time the monitor is put to sleep.

The built-in sensor is integrated inconspicuously and dust-protected in the edge of the monitor. Thanks to DUE technology, a homogeneous image display is guaranteed, which means it does not matter where the measuring sensor is located on the monitor. Each built-in sensor is calibrated and precisely adjusted at the factory with a high-precision reference spectrophotometer. The high-precision mechanics ensure there is only an extremely small distance between the measurement sensor and the monitor panel over the entire service life of the monitor, so ambient light does not affect the measurement.

Every EIZO ColorEdge is precisely calibrated and adjusted to the correct values at the factory. A highly sensitive professional spectrophotometer is used for this purpose. The gamma values of the primary colours red, green and blue in the brightness levels 0 to 255 are also measured and perfectly adjusted. As a result, the perfect combination is always selected from the billions of possibilities offered by the monitor"s 16- or 24-bit LUT (Look-Up-Table) to achieve perfect colour gradations every time. So the monitor is delivered perfectly factory calibrated. This is also the reason why EIZO recalibration is so fast. Since only the ageing process of the panel needs to be tracked during recalibration, it is sufficient to check certain support points and take their changes into account if necessary. Meaning, a time-consuming measurement of countless colour patches is not needed.

LCD monitors often have uneven brightness distribution and inconsistent colour purity across the monitor surface. These individual inaccuracies must be removed from a graphics monitor. To do this, EIZO measures each individual panel at the factory at numerous measuring points and corrects any colour and brightness deviations with its patented DUE technology (Digital Unifomity Equalizer). It is only this complex procedure which makes the use of an integrated sensor possible at all. Because only if the colour and brightness values at the edge correspond precisely to those on the rest of the display surface is a measurement at the edge also meaningful for the entire monitor.

Many post-production, VFX and television studios specify a particular spectrophotometer as the master sensor for their internal colour management. To avoid missing out on the advantages of the integrated sensor, it is possible to correlate the built-in sensor with an external master sensor. In this way, the built-in sensor adopts the measurement characteristics of the master sensor and retains its specific properties. A consistent workflow with monitors without a built-in sensor is thus guaranteed.

HDR content is becoming increasingly popular in the film industry. Extreme contrasts of up to 1,000,000:1 and brightness values of up to 1,000 cd/m² pose great challenges not only for the panel technology but also for the measurement sensor technology. Nevertheless, EIZO has succeeded in developing an integrated calibration sensor for the ColorEdge PROMINENCE CG3146 that meets the requirements of HDR applications.

While the built-in calibration sensor already means a great increase in comfort for the individual user with corresponding time savings, these time savings are multiplied accordingly in large usage scenarios. In large studios, agencies or publishing houses, people often work on joint projects across locations or even countries. This quickly brings together numerous workstations, on which the same files must naturally look the same. To achieve this, all monitors must be set to the same calibration targets and recalibrated regularly. The room for error is large and the calibration and maintenance effort enormous. To eliminate numerous sources of error and dramatically reduce the maintenance effort, EIZO offers a powerful overall colour management solution: the combination of monitors with built-in calibration sensor, the calibration software ColorNavigator and the cloud solution ColorNavigator Network allows a consistent colour-managed workflow to be centrally monitored, managed and maintained even across continents.

With ColorNavigator Network, a single administrator can provide centralised quality control of all ColorEdge CG monitors with a built-in calibration sensor on the network. The administrator can set colour modes, schedule automatic self-calibration, enable key locks, register or adjust asset management settings, and import and export monitor settings for each monitor. For large projects with multiple production steps, such as games or feature films, this ensures that the correct colour standards are used by everyone involved, and administrators can even assign custom settings for specific projects or jobs. The built-in sensor eliminates the need for a staff member to visit and recalibrate each monitor. This is done automatically. In addition, EIZO hosts the server for data exchange in a secure cloud, so there are no additional investments or ongoing costs for providing a server for the user.

The Academy of Motion Picture Arts and Sciences has honoured EIZO with the Scientific & Technical Award for the development of the CG Series ColorEdge monitors with built-in calibration sensors. The jury"s citation "EIZO"s automatically calibrating SDR monitors increase artists" confidence in the accuracy of image reproduction across the enterprise and reduce disruptions to the creative process and production workflows. They have become indispensable to many major motion picture animation and effects studios."

Mackevision trusts in the performance of the ColorEdge monitors and uses them in image production in all even remotely (colour) critical areas. Learn more