Compute the histogram with all the unique values, when using the classified renderer

Last Published: April 25, 2020


Instructions provided describe how to compute a histogram with all unique values when using a classified renderer.

When the classified renderer computes the class breaks, it does a quick estimate based on the histogram, by default.

If a more accurate classification needs to be calculated using each unique value, a Windows registry setting must be modified.

This knowledge base article does not apply to ArcGIS Desktop 9.3 Final. It is applicable to the ArcGIS Desktop 9.3 Raster Renderer Patch, ArcGIS 9.3 Service Packs, ArcGIS 9.3.1, and ArcGIS 10.0.


To calculate the classification using all the unique values, a new DWORD Value must be created in the registry. When the value is set to 0, the default quick computation is implemented. When the value is set to 1, an accurate computation using all the unique values is performed.

<pre class='ckeditor_codeblock' style=' background-color: #fff7cc; border: 1px solid var(--calcite-ui-warning);white-space: pre-wrap;font-family:Arial'><b>Warning:</b>
WARNING: The instructions below include making changes to essential parts of your operating system. It is recommended that you backup your operating system and files, including the registry, before proceeding. Consult with a qualified computer systems professional, if necessary.

Esri cannot guarantee results from incorrect modifications while following these instructions; therefore, use caution and proceed at your own risk.

  1. Open the registry. Click Start > Run, type regedit and press Enter.
  2. Navigate to Raster hive for the current user.

    • For ArcGIS 9.3.x, navigate to:


    • For ArcGIS 10.x, navigate to:


  3. Right-click on the Raster hive, point to New, and click on DWORD Value.
  4. Rename the new DWORD Value to ClassifyUsingUV.
  5. Right-click on ClassifyUsingUV. Click Modify.
  6. Change the value to 1.

Article ID:000010263

  • ArcMap
  • Legacy Products

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