The Enhance Contrast tool offers the possibility to increase the contrast in the 3D image data. Observe changes in the histogram when applying Enhance Contrast.

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

• For the given percentage of Saturated Bright Voxels the gray values are set to the maximum gray value (e.g., 255 for 8 bit images).
• For the given percentage of Saturated Dark Voxels the gray values are set to the minimum gray value of 0.
• The gray values of the intermediate voxels are equally distributed over the complete possible gray value range.

When you check the option Equalize Histogram, this feature will distribute the most frequent gray values more evenly across the histogram. The original distribution of gray values is then balanced, so that each gray value contains an equal number of occurrences on average. This especially pulls the most frequent gray values apart to reach the highest contrast possible.

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

The following examples show histogram results for the different settings. The gray values are separated and distributed to use the complete gray value range. Through the resulting gaps between the gray values the contrast is improved. Observe also the contrast changes in the slice visualization.