162 Hog 4 Operations Manual
6.3.5 Working with Colour
Fixtures that have continuously variable Colour mixing create Colour in different ways. The
two main systems are:
CMY: this system is used by most moving lights that have continuous Colour mixing;
the Colour is controlled by three parameters: Cyan (C), Magenta (M) and Yellow (Y).
Fixtures that use the CMY system start by producing white light, and then filter out the
unwanted Colours to leave the desired Colour; higher parameter values produce a
greater filtering effect, so that setting them all to 100% produces black. To avoid
wasting the light intensity of the fixture, you should always keep at least one of the
CMY parameters at 0%, setting the other two at higher values to get more saturated
Colours. For example, values of 0%C, 0%M, 20%Y will produce a pale yellow tint,
while 0%C, 100%M, 0%Y will produce a fully saturated magenta. Mixing two of the
Colours will produce further shades, so 50%C, 0%M, 50%Y will produce a middle-
saturation green.
RGB: this system is used mainly by fixtures based on LEDs. The Colour is controlled
by three parameters: Red (R), Green (G) and Blue (B); with the three parameters at 0%
the fixture produces no light output, and the higher than value of these parameters, the
greater the fixture's total light output. If the three parameters have equal values, then
the light output will be white (within the limits of the technologies used). Use one or two
of the parameters to get the Colour you want, and then add the other(s) to de-saturate it
(‘dilute’ it towards white). For example, values of 0%R, 0%G, 100%B will produce a
bright, saturated blue, while 80%R, 80%G, 100%B will produce a bright, blue tint.
50%R, 100%G, 100%B will produce a middle-saturation cyan.
While Hog 4 OS allows you to control the CMY or RGB parameters of fixtures directly, this
method has several disadvantages:
With both the RGB and CMY systems, it is difficult to remember what combination of
settings will achieve the Colour you want.
With both systems, Colour and fixture intensity are linked. Under the CMY system,
giving all three parameters values above 0% unnecessarily reduces the light output;
with the RGB system, fixtures often don't provide a separate intensity parameter so
you have to control it with the Colour parameters. However, it is usually much more
convenient when programming to keep Colour and intensity completely separate.
The different Colour systems, together with different lamp types used, make it difficult
to match Colours between fixtures of different types. Furthermore, during cross-fades
Colours tend not to remain matched through the duration of the cue, producing uneven
Colour fades.
Hog 4 OS solves these problems by using a third Colour system: Hue and Saturation (HS).
Under the HS system, a fixture's Colour is determined by two parameters:
Hue: the Colour's position in the possible range of Colours, from red, going through
yellow, green, cyan, blue and magenta, and finally returning to red. As the range ‘wraps
around’, you can visualize it as a circle with the Colours positioned around the edge,
with red at the top, green at the lower right, blue at the lower left, and the intermediate
Colours in between. The angle between 0 and 360 degrees specifies the hue of the
Colour: red has a hue of 0 degrees, yellow has a hue of 60 degrees, and cyan has a hue
of 180 degrees. See the image below: "The Colour Wheel”.
Saturation: how ‘strong’ or ‘pale’ the Colour is. Pale Colours have low saturation,
while strong Colours have high saturation. Saturation is specified as a percentage
between 0% (white) and 100% (the strongest possible saturation).
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