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Please read this page if you are experiencing monotor brightness, contrast or color issues.
How Imorgon Workstation Deals with Video Monitor Calibrations
The Imorgon workstation contains an internal software based monitor gamma correction algorithm. This means that it will not alter the monitor calibrations that may have been performed in the monitor or the graphic cards. This design is intentional so that if you are using other imaging software that need to rely on hardware based monitor calibration, the Imorgon workstation will not affect such adjustment.
The gamma corrections in the Imorgon software can be adjusted and our support staff can show you how this is done. It is performed on a per workstation basis.
This adjustment should be used to correct for minor differences in how Imorgon software displayes images compared to other programs that run on the same workstation. The base calibration of the monitor must be performed first.
How Variability Occurs In Video Monitors
Each monitor has its own characteristics and that also the property changes naturally with the age of the monitor. For flat panel monitors the backlight output will reduce over time. For CRT monitors the physical characteristics of light generation materials change over time, both resulting usually in darker and less contrast in images. These changes cannot be avoided and is the result of monitors "wearing out".
In addition to this, most (especially less expensive) consumer-grade display monitors will have greater manufacturing variabilities especially in the color balance. You can manually adjust the color balance as well as brightness and contrast using the controls on the monitor. These are easily accessible to anyone, and because of that, many users tend to self-adjust monitors to their own liking, which could bother other users. Most medical grade monitors, therefore, have an adjustment lockdown mechanism to prevent casual adjustments.
What Methods Are Available?
- Perform Side-By-Side Manual Adjustment
- Use graphics publisher grade monitor calibration system
- Use DICOM monitor calibration system.
- Use Self-Calibrating video monitors
- Tweak the inter-vendor differences among software that run on the same workstation.
Side By Side Monitor Adjustment
- This method is not a diagnostic quality procedure and it is not recommended since many of the adjustments are done subjectively. However, this will tell you if two (or more) monitors can be adjusted at all.
- To do this, bring up the monitors side to side and leave it powered on for at least 30 minutes for the light source to warm up completely.
- Next bring up the same large a image on both monitors. If you are using the Imorgon software, you can use the Compare Mode on the same study to accomplish this.
- You can use the same technique with other types of images. I recommend that you pull up large color images on both monitors with web browser.
- Use the RGB and Brightness and Contrast settings on the monitor to adjust the monitors. Note that you may need to adjust to the darker one of the two monitors if the maximum brightness of one of the monitor cannot match the other one.
Using Graphics Publisher Grade Monitor Calibration
- Asides from Medical Imaging industry, Graphics Arts and Design industry needs a high quality monitor calibration in order to match colors on the display to what come out on the target media of print, screen or video. Since there are a lot more people that need this solution in this industry this type of calibration system can be obtained less expensively than a full medical grade calibration system.
- This is significantly more desirable and less expensive than the DICOM calibrator, and it does do an excellent job of calibrating color balance and also great job on balancing the monitor contrast and brightness. It will be acceptable for Ultrasound viewing, but probably not acceptable for other modalities that require much more strict grayscale output curve requirements (CR, DR and CT).
- You can purchase monitor calibration system from various vendors that usually come with a detection pod (USB) and calibration software. Be sure that the graphics card you are using is supported by the specific model of the calibration system.
- Typically all you need to do is to intall the software, put the pod on the monitor and have it run through the calibration. For flat panel monitors, I usually put the monitor display surface flat on the table since holding that pod for 20-30 minutes on the vertical monitor is both tiring and inaccurate.
- On some higher end systems, there is a central monitor calibration management system that allows you to keep track of when and where you have performed monitor calibration.
Using DICOM Monitor Calibration System
- The DICOM standard defines a DICOM monitor "curve" and calibrating to this standard is almost a must if your workstations are used to view high contrast materials such as CR or DR images among other modalities. Ultrasound has a fairly low contrast resolution.
- The type I am familiar with and what we use is Dome/NDS (was Planar) C-Extra software. There are others from medical image monitor manufactures, please contact your vendor for suggestions. This solution can be used with any display monitors though the software may reject the monitor as "unable to calibrate" if the monitor is old or cannot support the range of color/ brightens/ contrast levels. Of course finding a monitor in your lot that cannot be calibrated is one of the reasons why you would use this type of software.
- Like the graphics art type calibration system, it requires calibration with a detector pod placed on the monitor.
- It alters the hardware look-up table in the graphics system, therefore, you can only use the graphics adapter that is supported by the vendor. Be sure to check the compatibility of this before you commit to this solution.
- This type of software also has a calibration lock-down mechanism so that un-authorized users cannot adjust the monitor settings.
- C-Extra has central monitor calibration management.
Using Self Calibrating Medical Grade Monitors
- Some high-end medical grade monitors have a self-adjusting calibration system built in the monitor. This is very ideal but the initial cost is high, though it may be argued that the total cost of the ownership could actually be lower since it does not require manual calibration intervention that is required with other solutions. Please consult with your monitor vendor if you need this type of solution.
Once the base graphics system have been calibrated, you can tweak the software gamma with the Imorgon workstation user interface. This can correct for minor difference in image quality while the same image is being displayed on the same workstation, for example on Philips iSite and Imorgon.
Prepared by Manabu Tokunaga