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H41: Reproduction
of Images: Colour Displays> The most common
method of generating colour by the additive system is visual display
units, such as computer display screens and television screens. Visual
display screens are composed of individual dots, which, at normal
viewing distances, are too small to be seen and the picture appears
continuous. |
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H42: Image RGB to
Display Colour XYZ> The steps in the conversion of the
RGB codes in an electronic image file to the brightness (luminance) of
the light emitted by the display screen are described. The power law
factor, white point for each of the standard types of display systems
are explained. |
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H43: Reproduction of
Images: Colour Printing> Four-colour printing is the
method
used for the reproduction of coloured illustrations in many newspapers,
magazines and on packaging materials. The technique is based on the
trichromatic nature of human colour vision in that, under normal
viewing conditions, there are three signals arising from the cone
shaped sensors in the retinal layer of the eye |
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H44: Image CYM to Print
Colour XYZ> The steps in the conversion of the
intended colour of a printed area (XYZ) to the relative areas of the
substrate covered by dots of cyan, yellow and magenta ink (CYM) is not
straightforward. It is simpler to consider the reverse transformation,
taking a set of known values for CYM and determining the colour of the
print (XYZ). |
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H45:
Management of Colour in
Images> The challenge of colour image
reproduction is to capture a scene and then to display or to print the
image with the highest possible fidelity to the appearance of the
original scene. At its simplest the reproduction chain of has four
stages: (scene capture) – (image storage) – (image display and editing)
– (copy production)
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H46: Measurement of Print> Reflection density is widely used
for quality and process control within the graphic arts industry. Once
the half-tone characteristics of a visually acceptable print is
established, densitometry offers a way of assessing the properties of a
print using parameters that are directly related to the half?tone
process. |
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