calibration photometer for lcd monitors in stock

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:

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Only the DustTrak™ DRX Aerosol Monitor 8534 can simultaneously measure both mass and size fraction. The DustTrak DRX handheld monitor is a multi-channel, battery-operated, data-logging, light-scattering laser photometer that gives you real-time aerosol mass readings. 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 handheld monitor measures aerosol contaminants such as dust, smoke, fumes and mists.

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.

Regardless of the needs of your practice or enterprise, Double Black Imaging offers an expansive variety of medical grade computer monitors that work on nearly all PACS medical imaging systems.

Double Black Imaging and Image Systems PACS monitors and large format Gemini Displays provide ultra-high contrast and brightness, Automatic DICOM 3.14 calibration through adjusting front sensors, and a larger, more efficient screen size. DBI’s PACS Monitors and clinical review displays are FDA approved radiology monitors that are specifically designed to meet diagnostic imaging requirements while providing solutions for DICOM calibrated displays outside the reading room.

Our color and monochrome PACS monitors range in resolution from one to eight megapixels, and the PACS imaging workstations eliminate the gap between screens with large format displays arranged in a multi-head display configuration.  In addition, all of Double Black Imaging’s PACS monitors come bundled with a comprehensive software suite which makes them easy to configure and remotely manageable via network. To ensure the performance of your medical review monitor’s capabilities, this calibration suite also includes a generous five-year warranty and customer support available via phone or with remote support.

The rise of digital imaging technology has quickly changed the way in which patient data is used and distributed within hospitals. Medical images, enriched with patient information, are being shared and reviewed beyond the PACS medical imaging System, becoming available in every hospital department.

DBI’s clinical review monitors and radiology LCDs are specially designed for versatile clinical healthcare applications in this hospital-wide network of electronic medical records.  Outperforming their commercial counterparts, these medical grade LCD computer monitors have higher brightness levels, better contrast ratios, backlight sensors for stable luminance control, and DICOM 3.14 compliance.  Backed by an industry-leading warranty and service program, the DBI Clinical review LCD line includes 20”-27”, 2MP – 8MP options, and these, paired with a custom radiology workstation, are the perfect fit for all your clinical imaging requirements.

Double Black Imaging’s and Image Systems PACS monitor family includes 2MP, 3MP, 4MP, 5MP, 6MP, and 8MP LED backlit displays. Many of these radiology LCD monitors offer color or monochrome options.

The comprehensive software suite included with all of Double Black Imaging’s Radiology LCD monitors makes them easy to configure and manage through the network, ensuring that your display devices meet diagnostic radiology requirements. They also include a generous warranty and customer support policy. In addition, all of these Medical Grade monitors are also fully compliant with the DICOM 3.14 standard and each radiology computer monitor is FDA approved for use with

All of Double Black Imaging’s PACS monitor display solutions are equipped with X-CAL or CFS Calibration software for remote calibration, conformance, report generation, and non-conformance alerts via the web. These monitors also include built-in front sensors for automatic DICOM 3.14 calibration, backlight sensors for time-tested stability, ambient light sensors. Additional workflow enhancement tools are included in the radiology imaging workstation, such as auto-dimming capability, image pinpointing, cursor wrap, and cursor genie functions that boost productivity and improve the user experience on these radiology monitors.

Because DICOM Calibration and Conformance for PACS monitors MUST be done from the front of the radiology LCD, this either requires a photometer for manual calibrations or built-in Front sensors. To ensure compliance, the DBI Calibration suite consists of both a local agent package and a network administrative package that is easily accessible via the web. Once paired with DBI displays, this combination enables remote calibration of each display to the DICOM gray scale display function (GSDF), easy monitoring of each display from a remote central location, automatic Email notifications sent when service is required, and total control of display settings, adjustments, and launching of calibrations/conformance remotely.

Double Black Imaging offers advanced technology, surpassing the standards of other industry providers, with an unparalleled reputation for customer service. We dedicate our efforts to discovering innovative imaging solutions from medical technology to ergonomic radiology workstation options that improve medical LCD monitor image quality and stability with the ultimate goals of making imaging more efficient and reducing healthcare costs.  Contact us today to learn more about the display devices for diagnostic radiology that we have to offer, from ergonomic radiology workstations and calibration software to radiology monitors for sale online.

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]

The Barco LCD sensor is an industry-leading colorimeter featuring Barco-specific calibration technology. Allowing seamless integration with QAWeb Enterprise – our unique online service for automated calibration, Quality Assurance, and asset management – this colorimeter offers the best value for money.

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.

The calibration of your system is an important step to make sure your experiments can be appropriately published as well as replicated on other systems. Full calibration is recommended each time the display settings have been modified. You can skip this section and jump directly to the Step-by-step Calibration Tutorial if you prefer.

Click on the Calibration icon in the toolbar at any time to access the Calibration panel. Psykinematix can help you calibrate several aspects of your experimental setup:

Several calibrations can be managed for each configuration of the display settings (display index where 0 refers to the main display, resolution, bit depth, and frame rate). Calibrated configurations appear in the pop-up menu at the top right of the calibration panel, while the calibrations attached to the selected configuration appear in the top left editable pop-up menu.

To create calibrations for a new configuration of the display settings (i.e. not yet present in the top right pop-up menu of the calibration panel), select the new settings in the Display Preferences and click on the small colored wheel icon

Note that changing the display settings in the Display Preferences (used by default when creating new experiments) updates the current configuration in this calibration panel.

The "+" and "-" buttons add and remove calibrations for the current configuration of the display settings. Control-clicking on the "+" button adds a copy of the current calibration; otherwise, a default calibration is created. You should rename any new calibration to reflect the display brand and type as shown in the example above.

Further details about the progress and status of the calibration can be found under the Summary tab where a button is associated with each calibration step. Each step button is referred either as:

If a calibration step is not completed and up-to-date, clicking on its button jumps to the associated tab where the calibration can be performed or completed (see below). For the Gamma calibration, the checked boxes indicate which guns remain to be calibrated.

Geometry calibration ensures that stimuli look the same on different displays in terms of their spatial properties (stimuli size in degrees, spatial frequency in cycle per degree, etc). Geometry calibration is carried out through the following panel (Click on the Geometry tab):

Click on the "Perform Calibration" button and a square with the specified appearance will appear in the center of the calibrated display. Measure each side of the patch using the ruler to make sure it appears square; if it does not, use the display controls to adjust its aspect ratio. Note the size of the square either in inches or centimeters, and press the ESC key to return to the panel view.

Note that the Geometry calibration is synchronized with the Display Preferences which indicate the field of view expressed in degrees and the maximal spatial frequency given a default viewing distance.

A successful Geometry calibration should be indicated by a green check mark in the progress status, you may then click on the "Next Step" button to move to the Gamma calibration.

Gamma calibration corrects for the intrinsic non-linearities in the display luminance and in the digital-to-analog conversion of the graphics card. This is especially important to minimize luminance artifacts in contrast-modulated patterns (2nd-order stimuli). To carry out the Gamma correction, you first need to estimate the Gamma of your display by measuring the light intensity (typically the luminance in Candela/m^2 or Nit) as a function of the pixel intensity (typically between 0 and 255) for each gun (Red, Green and Blue) and their linear combination (White) using either a photometer or a colorimeter.

Psykinematix uses the standard gain-offset-gamma (GOG) model to perform the Gamma correction on CRT displays (for details see: Berns 1996, Brainard et al 2002, Georgeson 2007). Because the GOG model may be inappropriate for LCD displays that often show a saturating transfer function, Psykinematix takes care of discarding the saturating luminance readings before fitting the GOG model. This generally provides an effective Gamma correction over an extended luminance range even if the display transfer function does not conform well to the standard GOG model.

Before starting the calibration, you have to specify which gun will be calibrated and how the luminance readings will be measured. These selections are made through the use of two pop-up menus as shown below:

the number of readings that uniformly sample the pixel intensity (the maximum number of readings is typically 256 on an 8 bits per pixel graphics card; an error message will be shown if more samples than allowed are requested);

Note that the bit resolutions for each pixel component and for its hardware Gamma lookup table provided by the graphics card are indicated, as they affect the quality of the Gamma calibration. More accurate Gamma corrections are obtained from a hardware Gamma lookup table with a bit resolution higher than the one of the pixel components (embedded 10-bit gamma correction is typically found in recent graphics cards and digital displays).

Click on the "Perform..." button and select the "Gamma Measurement" option. When a white square will first appear in the center of the calibrated display, you will be asked to position the photometric device, and then its pixel intensity will be changed for each sample. Depending on the measurement mode, you will have to either manually enter each photometer reading or wait until the device finishes on its own. When it is completed, you will be asked to press the ESC key to return to the panel view;

The luminance readings will be fitted with a Gamma function and displayed in the graphing window (filled squares for the measurements, continuous line for the fit). The fitted Gamma value is displayed in the "Gamma" text field, along with the minimum and maximum luminances. The correction is then directly derived from a Gamma function with the reciprocal Gamma value;

Click on the "Perform..." button and select the "Correction Checking" option to verify the accuracy of the Gamma correction. This process is identical to step 2 above;

Repeat the whole process for each gun. To compare the quality of the Gamma correction for the different measurements, use the check boxes on the left of the graphing window to select which guns are displayed (L for the RGB combination).

Finally, it is recommended to regularly perform a correction checking and redo the Gamma calibration if the correction is no longer adequate. It is also recommended to wait for the monitor to warm up and stabilize for about 1/2 to 1 hour before carrying out a Gamma calibration (especially for CRT monitors).

A successful Gamma calibration is indicated by a green check mark in the progress status, you may then click on the "Next Step" button to move to the Color calibration.

Depending on the role of color in your experiment, either device may be preferable. By measuring the spectral emission of the display, radiometric data specifies how much light reaches each type of cone (assuming some human cone fundamentals for the spectral absorption), and characterizes the stimulus in terms of cone excitation (at the perceptual level). The xy chromatic coordinates provided by a colorimeter are display-independent and may be more appropriate when the perception of color per se is under investigation (at the cognitive level).

Each method consists in measuring the color properties of a patch of a given size and surround appearance for each phosphor activation (and their combination, i.e. the white point).

Note that the number of days since the last calibration is indicated next to the calibration mode (Radiometric or Colorimetric). While the chromatic properties are generally not expected to change over time, it is still recommended to regularly perform a color calibration each time the display settings have been modified. It is also recommended to wait for the monitor to warm up and stabilize for about 1/2 to 1 hour before carrying out the Color calibration (especially for CRT monitors).

When selecting the "Radiometric Data" option, you are presented with an "LMS to RGB" matrix on the left and a graphing window on the right. The "LMS to RGB" matrix defines a transformation from the LMS color space (excitation for the Long-, Middle- and Short-wavelength sensitive cones) to the display-dependent RGB color space. Such a matrix is obtained by multiplying the spectral emission of each phosphor by the spectral absorption of each cone. These phosphor emissions and cone absorptions are plotted in the graphing window as a function of the light wavelength (continuous lines for phosphor emissions, dashed lines for cone absorptions, the P and C check boxes enable/disable each plot).

derived from some spectral measurements stored in a custom "SPD file" (Spectral Power Distribution for each phosphor as a function of the wavelength as measured by a spectrophotometer), or

The computation of the "LMS to RGB" matrix also depends on cone absorption. Cone fundamentals which have been proposed to model the cones sensitivity in the normal human eye characterize cone absorption (see http://www.cvrl.org/cones.htm). The "Cone Fundamentals" pop-up button provides three models (Smith & Pokorny 1975, Stockman & Sharpe 2000 for 2 and 10 degrees). The selected cone fundamentals are plotted in the graphing window along with the phosphors" SPD.

Note that in this mode, clicking on the "Perform Calibration" button still allows the presentation of the red, green and blue patches with maximum luminance; and their spectral distributions can be measured by an unsupported spectrometer.

As all displayable colors are formed from an additive mixture of the red, green and blue phosphor emissions, the color gamut of a display is a subset of all visible colors and is defined by a triangle in the CIE xy chromaticity diagram. When selecting the "Colorimetric Data" option, you are presented with an "xyL for RGBW" matrix on the left and a graphing window on the right representing the gamut of your display in a standard CIE chromaticity diagram. The "xyL for RGBW" matrix specifies the xy chromatic coordinates and the maximum luminance (in candela/m^2) for each phosphor as well as the white point. This set of xy coordinates defines the limits of the gamut triangle represented in the chromaticity diagram.

One of the supported calibration devices (see the "Supported Calibration Devices" section) is used to automatically measure the xy coordinates and maximum luminance.

Click on the "Perform Calibration" button: a white square will first appear in the center of the display being calibrated, you will be asked to position the colorimetric device, and then the patch chromaticity will be set to the requested phosphor. Depending on the measurement mode, you will have to press the ESC key or wait until the device finishes its chromaticity reading to return to the panel view;

In custom mode, you will have to enter the chromaticity coordinates for the specified phosphor in the "xyL for RGBW" matrix (CIE 1931). When using a supported colorimeter, the matrix will automatically be filled in with the chromaticity coordinates and maximum luminance. In both modes, the gamut triangle in the CIE chromaticity diagram will be updated with the new settings;

A successful Color calibration should be indicated by a green check mark in the progress status, you may then click on the "Next Step" button to move to the Summary tab to verify that all calibration steps have been performed.

Display calibration devices are photo-sensors that are mounted on the surface of the display screen and connected to the computer via a USB interface or some other link. During calibration they measure the light properties of test patterns that are displayed on the screen in sequence, and then send the data to the computer. Three types of devices are of interest for display calibration: photometers, colorimeters, and spectroradiometers.

Photometers are instruments used to measure the light intensity emitted by each phosphor, estimate its transfer function (Gamma), and produce individual Gamma correction lookup tables so a Gamma-corrected display appears linear to the human eye.Colorimeterscharacterize color samples to provide an objective measure of color characteristics, ie: the chromaticity coordinates of each phosphor as well as their luminances. As a matter of fact, they can be used as photometers but not as spectroradiometers. Spectroradiometers are instruments used to measure the properties of light over a specific portion of the electromagnetic spectrum, more specifically spectral power distributions of individual phosphors that compose a display. They can also be used as colorimeters and photometers.

Psykinematix aims to support as many calibration devices as possible, the only limitations being they have to be USB devices (or possibly connected through a Serial-to-USB adapter) and compatible with Mac OS X. If you own a device you would like to see interfaced with Psykinematix, please make a feature request using the feedback menu.

When a calibration device is selected at any step of the calibration process, information about the device (identity, type and connection status) and its settings are presented in a sliding drawer:

Before using the device, make sure to select the proper settings (in particular screen type and measurement mode as they directly affect the measurements). If the requested device is not connected, the drawer appears showing the device icon with an X through it, as illustrated below:

Bach M., Meigen T., and Strasburger H. (1997) "Raster-scan cathode ray tubes for vision research – limits of resolution in space, time and intensity, and some solutions" (HTML Link)

Fairchild M. D. and Wyble D. R. (1998) ""Colorimetric Characterization of the Apple Studio Display (Flat Panel LCD)"", Munsell Color Science Laboratory Technical Report (PDF Link)

Glasser J. (1997) ""Principles of Display Measurement and Calibration"", In: L.W. MacDonald and A.C. Lowe (Eds.) Display Systems: Design and Applications (pp. 261-288): John Wiley & Sons, Chichester

2.3. It is our particular concern that we protect and safely store all your personal data entrusted to us. This document provides more information on how we use and process personal data.

3.1. The personal data collected by Sigrist-Photometer AG are needed for the purposes of customer service and promotion. In addition, we analyse the usage patterns of visitors browsing the website for the purpose of personalisation and demand specific preparation of information. The data are collected, stored, processed and used for these purposes.

3.2. Sigrist-Photometer AG collects, processes and uses your personal data on the legal basis of Art. 6 (1) GDPR. The legal basis for the processing of your personal data are, on the one hand, legitimate interests in accordance with Art 6 (1) (f) GDPR and, on the other hand, your consent to the processing of your relevant personal data in accordance with Art. 6 (1) (a) (newsletter, contact form and cookies). Not providing the data may have various consequences.

3.3. Sigrist-Photometer AG processes your personal data, as far as necessary, for the duration of the entire business relationship (from initiation, handling until expiration of a contract) and, exceeding that, in accordance with the legal safekeeping and documentation obligations accruing from Swiss laws and until a possible legal dispute is ended, continual warranty and guarantee periods expire.

3.4. In the course of operating our website and analysing the usage patterns or visitors browsing our website, we assign processors, i.e. software and hosting service suppliers as well as agencies, which may access your personal data in the course of their work as far as these data are necessary for rendering their respective services. They have committed themselves to us to comply with the data protection provisions. Processing contracts in accordance with Art. 28 GDPR have been concluded. More detailed information concerning the processors can be requested at [email protected].

4.1. Your information and personal data given in our contact form is transmitted to us, processed and stored by us via our own mail server for the purpose of processing your enquiry. These data are not collected or passed on without your consent. However, without these data, your enquiry cannot be processed.

5.1. You can register for our newsletter on our website following a double opt-in process. After your registration, you will receive an e-mail requesting your confirmation of registration. Without your e-mail address, our newsletter cannot be transmitted. You can unsubscribe our newsletter at any time by activating the unsubscribe-link at the end of each newsletter.

5.2. For forwarding our newsletters, we assign a processor (newsletter service provider), who in turn committed themselves to us to comply with the relevant data protection provisions. A processor contract in accordance with Art. 28 GDPR has been concluded. More detailed information concerning the processors can be requested at [email protected].

5.3. Data processing is carried out in accordance with the legal requirements of Art. 6 (1) (a) (Consent) GDPR. You can find detailed information on our newsletter privacy statement here.

6.1. This website uses Google Analytics, a web analysis supplier of Google Inc. (»Google«), 1600 Amphitheatre Parkway Mountain View, CA 94043, USA. Google Analytics uses »cookies« which are text files that are saved on your computer to help t analyse how you use the website. The information generated by the cookie about your use of this website (including your IP-address) will be transmitted to and stored by Google on servers in the USA. The IP-address transmitted by your browser within Google Analytics will not be merged with other Google data. Google will use this information on behalf of the website operator for the purpose of evaluating your use of the website, compiling reports on website activities for website operators and providing other services relating to website activity and internet usage. If necessary, Google will transmit this information to third parties provided this is prescribed by law or if third parties process there data on behalf of Google. Our legitimate interest in the processing of data lies in these purposes. The use of Google Analytics is governed by § 15 (3) TMA or Art. 6 (1) (f) GDPR.

6.3. We have concluded a corresponding contract for data processing with the web analysis provider (»Google«), who committed themselves to us to comply with the valid data protection regulations. Detailed information on the processor can be requested at [email protected].

6.5. Data processing is carried out in accordance with the legal requirements of Art. 6 GDPR (in particular consent). You can find detailed data protection information on Google Analytics here.

In such a case, all your data stored will be anonymised and further used for statistical purposes only without personal references. Withdrawal of consent does not affect the legality of data processing carried out as a result of the consent until said consent was withdrawn.

8.1. Sigrist-Photometer AG will take technical and organisational safety measures for safeguarding stored personal data against accidental or deliberate manipulation, loss or destruction and against the access of unauthorised persons. Our safety measures are continually improved in accordance with technical progress.

9.1. 9.1.You have the right to be informed about your stored personal data at any time. Provided there is no legal retention period, you have the right to have your data deleted as well as to oppose its being processed. Moreover, you have the right to have your data corrected as well as to have its processing restricted, to the transferability of said data as well as to complain before the Swiss data protection authority (https://www.edoeb.admin.ch/edoeb/en/home.html).

Google Analytics uses »cookies« which are text files that are saved on your computer to help the website analyse how users use the site. The information generated by the cookie about your use of this website will be transmitted to and stored by Google on servers in the USA.

Sigrist-Photometer AG activated the IP-anonymization of this website. Accordingly, Google will shorten your IP-address within the member states of the European Union or in other contracting states of the European Economic Area beforehand. Only in exceptional cases will the complete IP address be transmitted to the Google server in the USA and shortened there. The IP address transmitted by your browser within Google Analytics will not be merged with other Google data.

Google will use this information on behalf of the website operator for the purpose of evaluating your use of the website, compiling reports on website activities for website operators and providing other services relating to website activity and internet usage. Our legitimate interest in the processing of data lies in these purposes. The use of Google Analytics is governed by § 15 (3) TMG or Art. 6 (1) (f) GDPR.

The data transmitted by us and linked with cookies, user identification (e.g. user ID) or advertising ID are automatically deleted after 14 months. The deletion of data reaching the end of their storage period is carried out automatically once month. You can find further information on conditions of use and privacy on https://www.google.com/analytics/terms/gb.html or on https://policies.google.com/?hl=en.

As an alternative to the browser add-on, especially for browsers on mobile devices, you can further prevent the collection by Google Analytics: an opt-out cookie is set preventing the futures collection of your data when visiting this website. This opt-out cookie works only in this browser and only for our website and is stored on your device. If you delete the cookies in this browser, you will have to re-set the opt-out cookies. Information on embedding the opt-out cookie can be found on:

If necessary, Sigrist-Photometer AG will implement other Google services to individualize advertisements (Google DoubleClick, Google Dynamic Re-Marketing, Google Tag Manager) or to compile conversion statistics (Google AdWords Conversion). If you do not want this, you can deactivate it with the following link: https://adssettings.google.com/authenticated

Sigrist-Photometer AG, Hofurlistrasse 1, 6373 Ennetbürgen, Switzerland (hereafter referred to as »Sigrist« or »we«) offer visitors browsing the Sigrist-Photometer AG website (www.sigrist.com, hereinafter referred to as »website«) a free subscription of the Sigrist newsletter (hereinafter referred to as »newsletter«).

In the following we provide information on the processing of personal data within the newsletter subscription in accordance with Art. 13 and Art. 14 of the General Data Protection Regulation (»GDPR«).

Date and time of confirmation of application (registration and confirmation) in double-opt-in process as well as the IP address of the terminal device used for confirmation, date and time of a possible deregistration of the newsletter

1 Cookies are small text files with information, which are saved on the terminal deviec of the user when they visit a website. In case of further accessing the website with the same terminal device, the cookie and the information stored therein can be accessed.

Double-opt-in process for confirming the newsletter subscription. For this, we send an e-mail requesting confirmation of the e-mail address provided at the registration. Subscription will only be active if the subscriber confirms the e-mail address with the confirmation link contained in said e-mail.

For determining the language and county-specific content of the newsletter, we use the language, the country and the country-specific version used for registration on the Sigrist-Photometer website.

Analysis of the user behaviour of newsletter subscribers in our newsletter and on our website as well as the preparation of user profiles while using pseudonyms as well as subscriber segments based thereon for the purpose of personalization and needs oriented design of the newsletter.

Newsletter service provider (simultaneously hosting service provider); for sending our newsletter, we assign a processor. They have committed themselves to us to comply with the valid data protection provisions. A processing contract in accordance with Art. 28 GDPR was concluded. More detailed information concerning the processors can be requested at [email protected].

We comply with the principles of data avoidance and data economy. Thus, we will only store your personal data for such a period as is necessary for fulfilling the purposes mentioned here (see Chapter D) or as is required by the various statutory storage periods. After the respective purpose ceases to apply or after those storage periods expire, the corresponding data shall be locked or deleted routinely and in accordance with the statutory provisions.

If personal data are processed for direct marketing purposes (see Chapter D), you shall have the right to object at any time to processing of personal data concerning you her for such marketing.

Go to www.qubyx.com/index.php/register and fill out the form. Enter the serial number provided above, the generated workstation ID, and user information.

To get the generated workstation ID the form requires, open the “Registration/Activation” window in the software and select manual activation type. The software will provide a generated workstation ID.

When the filled out form is submitted, you will receive an activation code by email. Enter this code into the corresponding field in the “Registration/Activation” window of the software and click “Activate”.

The upgrade is not free, but we offer special pricing on PerfectLum v4 for PerfectLum v3 users. Contact us at sales(at)qubyx(dot)com to receive a quote.

In PerfectLum you can check the calibration effect visually, using test patterns. After you have successfully calibrated the display, go to Tools > Display Test Pattern in PerfectLum main window. There you can choose one of the test patterns or any other image from your PC. Click “View and Check” to view the test image, and in the top right-hand corner you will see a button to switch off and switch on the calibration. If you want check the effect not on the test image, but just in general, use the PerfectLum LUT Loader tray icon (bottom right-hand corner). Right-click on it and you will see the name of your display(s) with a tick (this means that calibration LUT is applied on a display). Left-click on the display name to unapply the calibration LUT and to apply it again.

Verify if the sensor is connected correctly to the machine and if the USB port is active. Eventually change the port to test. Reboot the computer, and if you are still getting the error message, contact support(at)qubyx(dot)com for help on sensor installation.

1. choose what default regulation (AAPM, DIN, JESRA) and classification (primary, secondary) will your regulation be based on. Pick the name for your regulation and click “Continue” button;

2. in the next pop up window (Regulation Editor) select steps that will be included in your regulation by checking/unchecking boxes. Then select frequency of constan