Adobe PHOTOSHOP ELEMENTS Manual page 77

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. In
addition to being the default mode for new
Photoshop images, the RGB model is used by
computer monitors to display colors.
This mode uses one of two color
Bitmap mode
values (black or white) to represent the pixels in an
image. Images in Bitmap mode are called
bitmapped 1-bit images because they have a bit
depth of 1.
This mode uses up to 256 shades
Grayscale mode
of gray. Every pixel of a grayscale image has a
brightness value ranging from 0 (black) to 255
(white). Grayscale values can also be measured as
percentages of black ink coverage (0% is equal to
white, 100% to black). Images produced using
black-and-white or grayscale scanners typically are
displayed in Grayscale mode.
ADOBE PHOTOSHOP ELEMENTS
This mode uses at most 256
Indexed Color mode
colors. When converting to indexed color,
Photoshop Elements builds a color lookup table
(CLUT), which stores and indexes the colors in the
image. If a color in the original image does not
appear in the table, the program chooses the
closest one or simulates the color using available
colors.
By limiting the palette of colors, indexed color can
reduce file size while maintaining visual quality—
for example, for a Web page. Limited editing is
available in this mode. For extensive editing you
should convert temporarily to RGB mode. (See
"Converting to indexed color" on page 71.)
Converting between color modes
When you choose a different color mode
for an image, you permanently change the color
values in the image. Consequently, before
converting images, it's best to do the following:
• Do as much editing as possible in RGB mode.
Save a backup copy before converting. Be sure to
•
save a copy of your image that includes all layers in
order to edit the original version of the image after
the conversion.
• Flatten the file before converting it. The inter-
action of colors between layer blending modes will
change when the mode changes.
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User Guide