Editing Manual Area, Histogram, and Lookup Table color-balancing coefficients

When the selected color-balancing method is Manual Area, Histogram, or Lookup table, an existing lookup table (LUT) is applied to the raw pixels to produce a color-balanced image. In the Color Balancing Editing window, under LUT Editor, you can modify this LUT.

To edit the color-balancing coefficients

In the control pane, select the image for which you want to edit the color-balancing coefficients.
Click the Tools menu, point to Color Balance, and then click Edit.
The Color Balancing Editing window appears, showing the applicable color-balancing method. This is the method applied to the image when it was added to the mosaic.
To adjust the coefficients for an individual channel while leaving the other channels unchanged, clear the Adjust channels simultaneously check box, and then in the Channel list, select the channel you want to modify.
Note: The Adjust channels simultaneously check box is available only with multispectral images.
Drag the Contrast and Brightness sliders to the left or right, as necessary.
Under LUT Editor, in the Mask list, select the type of mask to apply.
You can select from the following:
- Entire raster: The entire image is used to compute the histograms. The two histograms displayed represent the raw (gray) and color-balanced (red) images. If previous modifications have been made to the color-balanced image, the red histogram reflects those changes.
- Current view area: Similar to Entire raster, except that the histograms are computed based on the pixels in the current view area (pixels within the cutline).
- Match area: The histograms are computed based on the existing match areas for the image. This option is only available if the image has match areas defined and the Manual Area color-balancing method has been computed.

If you are making changes to a single channel, you can modify the LUT for that channel using the toolbar buttons and options under LUT Editor.

Under Graph editing tools, use the toolbar buttons to modify the LUT graph. Each button is described in the following table.

Button	Name	Description
	Toggle	Switch the display in the Graph clipboard preview between the modified LUT and the original. Note: You must first copy a modified LUT before you can switch between previews.
	Copy	Copy the the current modified LUT and save it as a temporary backup. You can now click Toggle to switch the display between the modified LUT and the original.
	Manual Mode	Switch to manual mode, in which you can modify the histogram in the LUT graph.
	Add Breakpoint	Add a breakpoint in a specific location on the LUT graph.
	Move Breakpoint	Drag a breakpoint to a new location on the LUT graph.
	Delete Breakpoint	Remove a breakpoint from the LUT graph.
	Thin Breakpoints	Remove excess breakpoints along straight stretches associated with a LUT
	Edit Table	Open the Lookup Table window, in which you can modify the breakpoints and lookup values.

Under Functions, you can apply a different enhancement using the toolbar buttons. Each button is described in the following table.

Button	Name	Description
	No Enhancement	Does not apply an enhancement to 8U data types. This command does, however, apply a linear stretch or a linear enhancement to other data types using their pixel values. The stretch is applied using only those pixels displayed in the viewer. At a zoomed-out level, the pixel values are decimated before they are displayed in the viewer. Therefore, the range of pixels used for the linear stretch may be narrower than the actual range of pixels in the image file. This means that the actual minimum and maximum values in the image file may not be included in the calculation of the linear stretch. The settings of the Tail Trim and Exclude Min/Max check boxes are ignored for all data types.
	Linear Enhancement	Uniformly stretch the minimum and maximum values in the image over the entire available output-display range to enhance the overall differences in gray levels in the image.
	Root Enhancement	Compress the range of higher values (brightness) and expand the range of lower values (darkness), so you can distinguish more detail in darker areas of an image while still retaining some detail in the brighter areas.
	Square Enhancement	Compress the range of lower values (darkness) and expand the range of higher values (brightness), so you can distinguish more detail in brighter areas of an image while still retaining some detail in the darker areas.
	Adaptive Enhancement	Combine the benefits of Equalization and Linear enhancements for a more natural display than Equalization while effectively compensating for outliers.
	Equalization Enhancement	Distribute the values equally over the entire output-display range resulting in an almost uniform histogram. This enhancement is effective in exposing details in the higher values (brightness) and lower values (darkness), but causes less contrast in the middle values.
	Infrequency Enhancement	Assign the values that occur least frequently in the image to the range of higher values (brightness) in the histogram, so finer details become brighter.

To remove the upper and lower two percent of the image histogram and eliminate outliers in the upper and lower part of the pixel range, select the Tail Trim check box.
A margin of two percent is applied by default; however, you can adjust the amount of tail trim from one percent through five percent by selecting a value from the Tail Trimming list.
To disregard the lowest and the highest value in the image histogram before applying the tail trim, select the Exclude Min/Max check box.
If necessary, in the Tail Trimming list, click a new value of tail trim to apply (from one through five).
Modify the Min X, Max X, Min LUT (X), and Max LUT (X) values.
The Min X and Max X boxes correspond to the histogram of the raw image (before color balancing) and their values are constrained by the histogram of the raw image. The Min LUT(X) and Max LUT(X) boxes correspond to the minimum and maximum values of the color-balanced image (the one produced by applying the stored LUT). The values of the Min LUT(X) and Max LUT(X) boxes are constrained by those stored in the LUT for each image.