Hardware maintenance

Matching the display luminance to an external photometer

The correct functioning of Barco displays relies on the luminance measurements made using the integrated optical front sensor (I-Guard). Due to the aging effects of different components, the luminance output (unit: cd/m²) measured by this integrated sensor may eventually deviate from the actual luminance measured at the center of the screen using a properly calibrated external photometer. Additionally, some people want the display measurement to closely match the reading they obtain with their external photometer. While external photometers are approximately “photopic”, they will not match exactly the spectral characteristics of each display; the I-Guard is calibrated to the spectral characteristics of each display model.

Using the procedure described below, it is possible to match the integrated sensor to the external photometer. The following steps will be performed in this procedure:

  1. Using a supported external photometer, the white luminance (Lmax) is measured at center of the screen.

  2. The white luminance (Lmax) is measured using the integrated optical sensor.

  3. The difference between both measurements is evaluated. The internal gain factor of the integrated optical sensor is modified to make the measurement match the value measured by the external photometer. This modified gain factor is stored permanently in the display.

  4. The display’s integrated backlight stabilizer will react to reach the new absolute luminance, resulting in an increased or decreased luminance output (according to the relative measurements from internal sensor and the external photometer).

  5. The QAWeb Enterprise agent will require re-calibration of the display and can optionally perform the applicable QA tests.

Important

If performed incorrectly, internal sensor matching can have undesired effects on the luminance output and performance of the display. Please observe the following precautions and requirements:

  • It is recommended to verify the necessity of this procedure by contacting a Barco support representative.

  • The person executing the procedure must be familiar with DICOM calibration, display luminance and optical measurements.

  • Use only reliable external photometers. Do not use old photometers that have not been recently calibrated. Most external photometers should be considered less accurate one year after their last recalibration.

  • The display surface must be clean and dust-free.

  • Ensure a stable contact measurement using the external photometer, excluding ambient light. Avoid applying too much pressure on the displays (especially for models without a protective glass cover).

  • The display must be active for at least 60 minutes without interruption, to ensure a proper warmed-up state.

  • Performing a display factory reset discards the effects of this sensor matching. As a consequence, it may be required to execute the matching procedure again after the factory reset.

To start the procedure of matching displays:

  1. Navigate to the Hardware Maintenance section of the user interface.

  2. Click Match Luminance to External Photometer.

    _images/match_iguard_overview.png

  3. Identify yourself in the Operator text field and confirm that your are authorized to perform this action.

    _images/match_iguard_operator_selection.png

  4. Select the external optical sensor. If exactly one supported sensor is already attached, this step is skipped and the sensor is automatically selected.

    _images/match_iguard_sensor_selection.png

  5. Select the one or more displays to perform the matching procedure. Only Barco displays with an integrated front sensor are selectable. Certain Barco display models that do not support the matching procedure are not selectable. Displays must have been active continuously during the last 60 minutes to ensure a warmed-up state.

    _images/match_iguard_display_selection.png

  6. Carefully position the external photometer on the indicated white patch on the center of the display and activate the Measure button. Repeat this step for each selected display.

    _images/match_iguard_measurements.png

  7. After all selected displays have been measured, a summary page is shown, providing details of the applied correction. If a problem was encountered, the details will be reported here.

    _images/match_iguard_summary.png

  8. In the last step of the procedure, you can select which additional QA tests should run on the selected displays. Executing the calibration is mandatory and cannot be unselected. Click Finish.

    _images/match_iguard_final_tasks_selection.png

After completing the procedure, the Agent will execute the calibration task and optionally selected QA tasks in the background. If you have selected QA tests that require user invention, wait until the automated tasks have completed, and then execute these manual tasks.

Optimize I-Guard area

This hardware maintenance task is only available when a MDNC-6121 or MDNC-3421 Barco display is connected to the workstation. This task should be executed when the white luminance, measured with an external sensor, is markedly higher than the white luminance reported by the I-Guard sensor. The result of this task will be to examine and possibly adjust the I-guard area, which is used to stabilize the display white luminance at the calibrated level.

Executing the procedure does not require an external sensor. Follow the steps of the wizard to complete the procedure:

  1. Identify yourself in the Operator text field.

  2. Select one or more displays (MDNC-6121 or MDNC-3421).

  3. Wait until the procedure completes and the result summary page is shown.

  4. In the last step of the procedure, you can select which additional QA tests should run on the selected displays. Executing the calibration is mandatory and cannot be unselected. Click Finish.