Hello,
In the Rendering Editor panel of the Volume Viewer app, you can add points in the "Opacity vs Image Intensity" curve and tweak those points to see the change in intensity of the 3-D volume.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1738016/image.png)
Further, you may use different color maps selecting from the "Built-in Colormaps" dropdown menu and slide around the color slider depending on the color map.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1738021/image.png)
Following the above suggested steps you may be able to adjust the contrast while viewing a 3-D volume in the Volume Viewer app.
Also, you may refer the following MathWorks documentation page for more details on refining the view of your Volume data using the Volume Viewer app:
Hope it helps!
Regards,
Chandrika