Adobe PHOTOSHOP ELEMENTS Manual page 105

To use the Threshold command to convert images to
black and white:
Do one of the following:
1
Choose Image > Adjustments > Threshold.
•
• Create a new Threshold adjustment layer, or
open an existing Threshold adjustment layer. (See
"Using adjustment layers and fill layers" on
page 181.)
The Threshold dialog box displays a histogram of
the luminance levels of the pixels in the current
selection.
Drag the slider below the histogram until the
2
threshold level you want appears at the top of the
dialog box, and click OK. As you drag, the image
changes to reflect the new threshold setting.
To use the Threshold command to identify
representative highlights and shadows:
Open the Threshold dialog box.
1
Select Preview.
2
To identify a representative highlight, drag the
3
slider to the far right until the image becomes pure
black. Drag the slider slowly toward the center
until some solid white areas appear in the image.
To identify a representative shadow, drag the
4
slider to the far left until the image becomes pure
white. Drag the slider slowly toward the center
until some solid black areas appear in the image.
These represent the darkest pixels areas in the
image.
Reset the dialog box by pressing Alt (Windows)
5
or Option (Mac OS).
ADOBE PHOTOSHOP ELEMENTS
6 Click Cancel to close the Threshold dialog box
without applying changes to the image.
Using the Posterize command
The Posterize command lets you specify the
number of tonal levels (or brightness values) for
each channel in an image and then maps pixels to
the closest matching level. For example, choosing
two tonal levels in an RGB image gives six colors,
two for red, two for green, and two for blue.
This command is useful for creating special effects,
such as large, flat areas in a photograph. Its effects
are most evident when you reduce the number of
gray levels in a grayscale image. But it also
produces interesting effects in color images.
Original image, and Posterize applied
If you want a specific number of colors in your
image, convert the image to grayscale and
specify the number of levels you want. Then convert
the image back to the previous color mode, and
replace the various gray tones with the colors
you want.
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User Guide