The Enhance Contrast tool increases the contrast of 3D image data. Observe the changes to the histogram when applying the tool.

Using Saturated Bright and Dark Voxels changes the gray value distribution in an image. With 0% of each, the gray values are automatically distributed across the entire gray value range. This is also possible in Sample to 8 / 16 bit. Increasing the percentages narrows the range of considered gray values by ignoring a given percentage of bright and/or dark gray values, respectively. Thus, higher values increase contrast. In detail:

• The gray values are set to the maximum gray value (e.g., 255 for 8-bit images) for the given percentage of Saturated Bright Voxels.
• The gray values are set to a minimum of 0 for the given percentage of Saturated Dark Voxels.
• The gray values of the intermediate voxels are distributed evenly across the full range of possible gray values.

Checking the Equalize Histogram option distributes the most frequent gray values more evenly across the histogram. This balances the original distribution of gray values, ensuring an equal number of occurrences on average for each value. This pulls the most frequent gray values apart, reaching the highest possible contrast.

Click Apply to enhance the contrast in the image using the current settings.

The following examples show the results of the histograms for the different settings. The gray values are separated and distributed in order to utilize the full range of gray values. The resulting gaps between the gray values improve the contrast. Note the contrast changes in the slice visualization as well.