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The diagram is in the form of an ENC and so can be displayed using any of the three color
tables.
The color tables should be checked subjectively by means of the color differentiation test
diagram as follows:
1. The person carrying out the test should have passed the Isihara color blindness
test, or other test used to qualify bridge watch keepers, and should adapt to night
viewing for 10 minutes before checking the night display.
2. The controls should be set to their calibrated settings.
3. Under the current ambient condition, display the appropriate color differentiation test
diagram. Select each table and ensure that:
- Each foreground diagonal line is clearly distinguished from its background.
- The foreground lines representing yellow, orange, magenta (purple), green,
blue and grey may be clearly identified.
Grayscale Test
The Grayscale test is a visual test that is used to determine the color tracking of the display.
It requires judgment on the part of the operator to use.
The Grayscale shall consist of at least 8 steps from black to white on the screen. The
grayscale shall be made of rectangles that are at least 2.5 cm by 10 cm. These can be
oriented in either the horizontal or vertical direction. The Grayscale is critically observed by
the viewer from a distance of about 50 cm to 100 cm.
The observer will see either a grayscale that is pure and free from coloring, or one which
shows varying degrees of shading. If no coloring is seen, then the display is performing
properly. If slight shading is seen, then the display is useable. If there is a lot of shading,
then the display may be providing false color information.
This test should be used as an indication of performance of the display, but not as an
absolute measure. It should be noted that the identification and the degree of acceptance
will vary according to the operator, so should not be considered as a quantitative test.
Setting Backlight Brightness for ECDIS Operation
The display is initialized for ECDIS operation by sending the ‘BRT’ command to set the
proper backlight level corresponding to the ECDIS color table, DAY, DUSK or NIGHT, being
used. The Green ECDIS LED is illuminated indicating that the display is calibrated and
ready for ECDIS operation.
The color corrected VGA or DVI-D video data is supplied for presentation on the display.
If the backlight brightness is adjusted up or down the RED ECDIS + LED or the RED
ECDIS – LED, respectively, will illuminate indicating the display is out of calibration and in
which direction.
