Adobe 13101332 - Photoshop - Mac User Manual page 87

Adobe Photoshop Help
Using Help | Contents
Although you can use the HSB model in Photoshop to define a color in the Color palette or
Color Picker dialog box, there is no HSB mode available for creating and editing images.
A
B
HSM model:
A. Saturation B. Hue C. Brightness D. All hues
RGB model
A large percentage of the visible spectrum can be represented by mixing red, green, and
blue (RGB) colored light in various proportions and intensities. Where the colors overlap,
they create cyan, magenta, yellow, and white.
Because the RGB colors combine to create white, they are also called additive colors.
Adding all colors together creates white—that is, all visible wavelengths are transmitted
back to the eye. Additive colors are used for lighting, video, and monitors. Your monitor,
for example, creates color by emitting light through red, green, and blue phosphors.
Additive colors (RGB)
RGB mode
Photoshop's RGB mode uses the RGB model, assigning an intensity value to each pixel
ranging from 0 (black) to 255 (white) for each of the RGB components in a color image.
For example, a bright red color might have an R value of 246, a G value of 20, and a B value
of 50. When the values of all three components are equal, the result is a shade of neutral
gray. When the value of all components is 255, the result is pure white; when the value is 0,
pure black.
RGB images use three colors, or channels, to reproduce up to 16.7 million colors on-screen;
the three channels translate to 24 (8 x 3) bits of color information per pixel. (In 16-bit-per-
channel images, this translates to 48 bits per pixel, with the ability to reproduce many
more colors.) In addition to being the default mode for new Photoshop images, the RGB
model is used by computer monitors to display colors. This means that when working in
color modes other than RGB, such as CMYK, Photoshop uses RGB mode for display
on-screen.
Using Help | Contents
| Index
C
D
| Index
Working with Color
Back 87
Back 87