Aligning Stimuli with Polarised Mask

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The test stimuli must be carefully aligned with the polarizing filters. To allow for differences in the dimensions of different displays and variations in the exact positioning of the mask, Test Chart 2016 allows the polarised test stimuli to be repositioned. This is achieved as follows:


Select Options... General Settings from the main menu at the top of the screen.


This will display the Program Options window.  Select the Polar positioning tab (see below).



The positioning of the polarised window and its constituent elements can be specified to the nearest pixel from this panel.



The main test chart is normally positioned to the right of the mask (as you look at the screen) and as shown above.


All positioning measurements are in pixels.


The Polarised mask positioning should be adjusted first.


Assuming that the screen is 1920 x 1080 pixels (typical for a 24'' display) and is the Primary monitor, the Mask Left position will be 0, the Mask width is usually approximately 500, Test chart left will be the same as the mask width (500) and the Test Chart width will be (1920-500 = 1420). Mask height will be 1080.  Adjust these parameters until the mask area on the screen and the Test Chart are aligned as shown above and the mask area on the screen is matched to the width of the mask.


The Test chart left position and width is adjusted from the Windows positioning tab as shown below.





The individual components within the polarised mask screen can now be accurately aligned by changing the top and left value for each component.  These relate to the screen positioning as shown below:



NOTE:  A smaller polarised mask is available for 20'' monitors.  This mask does not have the filters for the Suppression test.  If this mask is being used, the Show suppression test check box should be un-ticked.


When all elements are correctly aligned with the mask select Save. Test Chart 2016  will automatically remember this position so that the windows will be correctly aligned when this test is used again.