Microtek ArtixScan M1 Pro User Manual page 28

One of ScanWizard Pro's strengths is its ability to let you work in the LCH color
space. Unlike the RGB color model, which corresponds to the color space as defined
in monitors and printers, the LCH color model is a more intuitive way of working
with colors, based on the values of Lightness (the "L" in LCH), Chroma (C), and Hue
(H). For instance, if you wish to change the color of the sky in an image to a darker
blue, your own eye — and your own judgment — will be the guide to making those
color changes. This is easier than, say, knowing the mathematical equivalent in RGB
or CMYK values that would correspond to a "dark sky blue".
The LCH model, in effect, makes it easier to comprehend colors as they are couched
in the terms we are familiar with: Lightness (how dark or light a color is), Chroma or
saturation (how rich or dull a particular hue of green is), and Hue (the property that
distinguishes, say, the color red from the color blue.)
In the LCH color model, colors of equal brightness lie on a single plane of the model,
as shown below. Red and green lie opposite each other on the horizontal axis, as blue
and yellow lie opposite each other on the vertical axis.
On the color sphere shown below, you can see how the different LCH properties play
out:
• The different hues (red, green, yellow, blue) are spread around the sphere.
• The chroma (saturation) for each hue increases from the center of the sphere
outward, with the most saturated colors lying on the edge of the sphere.
• The brightness values increase from the bottom of the model to the top