Konica Minolta DiMAGE Scan Dual III AF-2840 - Manual (Page 90)

A
N INTRODUCTION TO COLOR
90
Adding or subtracting equal parts of red, green, and blue will have no effect on the color balance.
However, it can change the overall image brightness and contrast. Usually, no more than two color
channels are needed to color balance an image.
Color balancing is a skill that develops with practice. While the human eye is extremely sensitive
in making comparative judgements, it is a poor tool when making absolute measurements of
color. Initially, it can be very difficult to distinguish between blue and cyan, and red and magenta.
However, adjusting the wrong color channel never improves an image; subtracting blue from an
image that is too cyan will give a green cast to the image.
If the image is too…
RED
GREEN
BLUE
CYAN
MAGENTA
YELLOW
Decrease the amount of green.
Decrease the amount of blue.
Increase the amount of red.
Increase the amount of green.
Increase the amount of blue.
Decrease the amount of red.
Knowing the complementary colors is very important in color balancing. If the image has a specif-
ic color cast, either subtracting the color or adding its complementary color will create a natural
looking image.
Complementary colors
Primary (RGB) and secondary (CMY) colors
The RGB color model is an additive process that uses the primary colors of light: red, green, and
blue. An additive color system mixes the three colors to recreate the entire spectrum of light. If all
three colors are mixed, white light is produced. Television sets and computer monitors use RGB to
create images.
The CMY color model is a subtractive process that uses the secondary colors: cyan, magenta,
and yellow. A subtractive color system recreates color with pigments and dyes to absorb unwant-
ed color. If all three colors are mixed, black is produced. Film-based photography is a subtractive
process. Printing technology is also a subtractive process, but, unlike photographic systems, it
requires a black channel (K). Because of the imperfections of printing inks, cyan, magenta, and
yellow cannot produce a true black when mixed, printers use what is called a four-color process
(CMYK) to reproduce images.
In photography, red, green, and blue are the primary colors. The secondary colors, cyan, magen-
ta, and yellow, are made from combining the primary colors: cyan = blue + green, magenta = blue
+ red, and yellow = red + green. The primary and secondary colors are grouped in complemen-
tary pairs: red and cyan, green and magenta, and blue and yellow.