The histogram displays a distribution graph of the red, green, blue, greyscale, hue, saturation, and lightness values in an image. You can analyze the distribution of detail in the shadows (shown in the left part of the histogram), in the midtones (shown in the middle), and the highlights (shown in the right part) and decide how to make corrections.
After you analyze the histogram, you can correct the image with Paint Shop Pro’s color and contrast correction commands or you can use commands that adjust your image based on its histogram features: Equalize, Histogram Adjustment, and Stretch.
Do I need the histogram? For image editing professionals, the histogram is a powerful tool for understanding and correcting images. For casual users, getting familiar with the histogram may not be necessary. Paint Shop Pro offers many simpler ways to adjust images. For information on how to begin correcting your photos, see How to Approach Color, Contrast, and Saturation Adjustments.
To display the histogram for an image:
To limit the histogram data to a specific area, make a selection in the image. See Using the Selection Tools.
Choose View > Palettes > Histogram or press F7.
The graphs represent the distributions of values of the selected channels. The vertical axis shows the relative number of pixels, ranging from zero to the maximum of all selected channels. The horizontal axis represents the channel value, always in the range of zero to 255.
For detailed information on the graph, see Understanding Histogram Values and Guidelines for Analyzing the Histogram.
Mark or clear the check boxes below the graph to display or hide the values for the channels.
Choose the image data that is graphed:
Sample merged If this check box is marked, the histogram graphs all layers in the image. If this check box is cleared, the histogram graphs only the current layer.
Selection only If this check box is marked, the histogram graphs only the active selection. If the check box is cleared, the histogram graphs the entire layer or image.
Do one of the following:
To view information about a specific value, place the cursor at that point on the histogram.
To select a range of values, click and drag in the graph. When you release the mouse, the range is deselected.
These fields show information about the selected point or range
Value(s) The value or range of values (from 0 to 255) of the point over which the cursor is positioned in the graph.
% in Range The percent of image pixels that are the value(s) of the selected point or range. The number in parentheses is the number of pixels that are the selected value(s).
% Above The percent of image pixels that are above the value(s) of the selected point or range.
% Below The percent of image pixels that are below the value(s) of the selected point or range.
To view the mean and median values for a channel, in the Display channel drop-down list choose a channel: Red, Green, Blue, Hue, Saturation, Lightness, or Greyscale. The Mean field displays the average value for the selected channel. The Median field displays the middle value in the range of values for the selected channel.
Note: The Display Channel specifies which channel is used to compute the six statistics shown immediately below it. It does not affect the display of the histogram graphs.
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Adjusting Individual Brightness Values
Adjusting the Brightness and Contrast in Unison
Adjusting the Brightness of the Highlights, Midtones, and Shadows
Adjusting the Lightness Levels
Manually Adjusting Brightness and Contrast