Adobe photoshop elements User Manual
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ADOBE PHOTOSHOP ELEMENTS
User Guide
To display the histogram for an image:
1
To display histogram data for a portion of the
image, first select that portion. By default,
the histogram displays the tonal range of the
entire image.
the histogram displays the tonal range of the
entire image.
2
Choose Image > Histogram.
The horizontal axis of the histogram represents
the intensity values, or levels, from darkest (0)
at the far left to brightest (255) at the far right;
the vertical axis represents the total number of
pixels with a given value.
the intensity values, or levels, from darkest (0)
at the far left to brightest (255) at the far right;
the vertical axis represents the total number of
pixels with a given value.
Note: The histogram for an adjustment layer reflects
the data for all visible layers beneath it.
the data for all visible layers beneath it.
3
For RGB images, choose an option from the
Channel menu. You can plot either the luminance
of the composite channel (Luminosity) or the
intensity values of an individual channel.
of the composite channel (Luminosity) or the
intensity values of an individual channel.
4
To view information about a specific point on
the histogram, place the pointer there. To view
information about a range of values, drag in the
histogram to highlight the range. When you are
finished, click OK to close the histogram.
information about a range of values, drag in the
histogram to highlight the range. When you are
finished, click OK to close the histogram.
Statistical information about the intensity values
of the pixels appears below the histogram:
of the pixels appears below the histogram:
Mean
Represents the average intensity value.
Standard deviation (Std Dev)
Represents how
widely intensity values vary.
Median
Shows the middle value in the range of
intensity values.
Pixels
Represents the total number of pixels used
to calculate the histogram.
Level
Displays the intensity level of the area
underneath the pointer.
Count
Shows the total number of pixels corre-
sponding to the intensity level underneath
the pointer.
the pointer.
Percentile
Displays the cumulative number of
pixels at or below the level underneath the pointer.
This value is expressed as a percentage of all the
pixels in the image, from 0% at the far left to 100%
at the far right.
This value is expressed as a percentage of all the
pixels in the image, from 0% at the far left to 100%
at the far right.
Cache Level
Shows the setting for the image
cache. If the Use Cache for Histograms option is
selected in the Memory and Image Cache
(Windows) or Image Cache (Mac OS) preferences,
the histogram displays more quickly and is based
on a representative sampling of pixels in the image
(based on the magnification), rather than on all of
the pixels (equivalent to a cache level of 1).
Deselect this option if you want to check for
posterization in the image. You can press Shift
while choosing Image > Histogram to generate the
histogram using all pixels in the image.
selected in the Memory and Image Cache
(Windows) or Image Cache (Mac OS) preferences,
the histogram displays more quickly and is based
on a representative sampling of pixels in the image
(based on the magnification), rather than on all of
the pixels (equivalent to a cache level of 1).
Deselect this option if you want to check for
posterization in the image. You can press Shift
while choosing Image > Histogram to generate the
histogram using all pixels in the image.
Adjusting tonal range
You can adjust the tonal relationships between
pixels in an image using a variety of commands.
Some commands—such as Auto Levels and
Auto Contrast—automatically correct the tonal
range of an image. Other commands—such as
Adjust Backlighting, Fill Flash, and Brightness/
Contrast—give you more control over the tonal
adjustments. Finally, the Levels dialog box gives
you the most precision when adjusting the tonal
relationships in an image.
pixels in an image using a variety of commands.
Some commands—such as Auto Levels and
Auto Contrast—automatically correct the tonal
range of an image. Other commands—such as
Adjust Backlighting, Fill Flash, and Brightness/
Contrast—give you more control over the tonal
adjustments. Finally, the Levels dialog box gives
you the most precision when adjusting the tonal
relationships in an image.