Performing calibrations Archives - MyXrayDose

Performing a Calibration

Sys Admin (Brian Lunt) — Wed, 02 Nov 2022 04:39:02 +0000

Calibrating a Display

To calibrate a display, first identify the monitor you wish to calibrate. When you click on a display in the list, an overlay will be displayed on the corresponding monitor. To identify all displays at once, press Identify Displays.

Ensure an OEM X-Rite photometer is connected. Then place the photometer sensor (glass side) down in the center of the selected display, hanging the counterweight over the backside of the monitor. Ensure the diffusor cover is not over the sensor.

Press Start Calibration to begin calibrating the display, this may take a few minutes depending on the selected number of samples. Ensure the photometer remains steady throughout the process for optimal results.

Once the calibration is finished, the window will automatically close and the results will be displayed:

Using your Results

After one or more calibrations have been completed, you can use these results in various ways. To generate a PDF report of the current calibration status of your display setup, click Print Report.

If you have a ViewIQ website subscription, you can also upload the results of each calibration to the website.

The post Performing a Calibration appeared first on MyXrayDose.

Illuminance, Ambient Luminance & Uniformity

Alex Hitman — Thu, 14 Mar 2024 15:49:50 +0000

Many standards require multiple types of measurements for a complete report, such as illuminance or uniformity. Room lighting can also affect the calibration, and can be accounted for by setting ambient luminance. These options are available under each display:

Illuminance

Illuminance is the amount of light that falls on a surface per unit area. Many standards require this to be below a certain threshold. To measure illuminance, place your photometer on the screen with the lens pointing outward and the diffuser covering the sensor:

Click Measure Illuminance to take a reading, which will then be displayed in the Lux tile:

Ambient Luminance

To set ambient luminance for a display, click on the edit icon in the ambient luminance tile:

A popup will appear, where the value can be set:

For an accurate measurement using a photometer, it is recommended to:

Turn off the display for which ambient luminance is being measured (two or more displays are needed)
Ensure the diffuser is not covering the sensor
Hold the photometer in approximately the same location as where an observer would be looking from
Face the sensor toward the display and click Measure to take a reading

The ambient luminance field will be updated with your measurement

Uniformity

To measure uniformity, click Measure Uniformity. The following window will open:

With your photometer ready, place the sensor within the circle of the light gray box and click OK to start. When each reading is taken, move the sensor to the next circle and repeat (readings will be taken automatically). After the last reading is taken the window will close, and the value can be found under the Uniformity tile

The post Illuminance, Ambient Luminance & Uniformity appeared first on MyXrayDose.

Adjusting calibration settings

Alex Hitman — Thu, 14 Mar 2024 15:50:46 +0000

Overview

Calibration settings can be changed under the Settings > Measurement Settings tab:

Here you can adjust various factors that influence calibrations such as:

Sample count (for greater accuracy)
CIE D65 colour calibration
Minimum and maximum luminance targets
Colour dithering

Sample count

The number of calibration samples impacts the time taken to complete calibration as well as the accuracy of the final calibration applied. Using a larger number of samples for Calibration Points may help to reduce GSDF. For most purposes, using 52 or 64 samples is optimal.

Note: For maximum GSDF accuracy, 1786 calibration points can be used. However, to select this option, colour calibration must be disabled, dithering mode set to partial or full, and LUT bit depth to be set to 8-bits

The sample count for the check phase of the calibration should be set to 18 to for valid GSDF values.

CIE D65 Colour Calibration

To enable CIE D65 color calibration for your monitor, toggle the CIE D65 colour calibration option. This will be applied on the next calibration that is run.

Enabling this option may reduce the maximum luminance for your display to below what it is capable of, as some tradeoffs have to be made to correct for colour. If your display no longer meets the luminance requirement for your selected standard after applying colour calibration, it is recommended you disable this option. This setting is also not compatible when a dithering mode is selected.

Luminance Targets

All radiology display standards have requirements for minimum and maximum luminance. By default, ViewIQ will target a minimum luminance of 1 cd/m2 and use the maximum luminance your display is capable of. This should allow for most standards to be met without having to make any changes (assuming that your display hardware is capable of meeting the standard).

However, you might want to adjust these targets to preserve your display (by reducing maximum luminance to that of the standard being used) or when using a custom standard. To set the minimum and maximum luminance enter your values into their respective fields and run a calibration:

Colour Dithering

GSDF can be further improved when colour channels are individually incremented, as this allows the calibration to make use of a greater range of luminance values. To enable dithering, expand Advanced Options

Then from the colour dithering drop down, select Partial or Full dithering.

Full dithering may cause unintended results with colour production. If this is experienced, use Partial dithering instead.

The post Adjusting calibration settings appeared first on MyXrayDose.