How to use a raster unique value renderer

This sample shows the basics of using RasterUniqueValueRenderer.
How to use

Add a raster layer that has a table into to ArcMap and make sure it is first layer.
Run the procedure in ArcMap Visual Basic Editor.
[VBA]

        Sub ChangeRenderToUVRenderer()
    
    Dim pMxDoc As IMxDocument
    Set pMxDoc = ThisDocument
    Dim pMap As IMap
    Set pMap = pMxDoc.FocusMap
    
    ' Get raster input from layer
    Dim pRLayer As IRasterLayer
    Set pRLayer = pMap.Layer(0)
    Dim pRaster As IRaster
    Set pRaster = pRLayer.Raster
    
    ' Get the number of rows from raster table
    Dim pTable As ITable
    Dim pBand As IRasterBand
    Dim pBandCol As IRasterBandCollection
    Set pBandCol = pRaster
    Set pBand = pBandCol.Item(0)
    Dim TableExist As Boolean
    pBand.HasTable TableExist
    If Not TableExist Then Exit Sub
    Set pTable = pBand.AttributeTable
    Dim NumOfValues As Integer
    NumOfValues = pTable.RowCount(Nothing)
    
    ' Specified a field and get the field index for the specified field to be rendered.
    Dim FieldIndex As Integer
    Dim FieldName As String
    FieldName = "Value" 'Value is the default field, you can specify other field here.
    FieldIndex = pTable.FindField(FieldName)
    
    ' Create random color
    Dim pRamp As IRandomColorRamp
    Set pRamp = New RandomColorRamp
    pRamp.Size = NumOfValues
    pRamp.Seed = 100
    pRamp.CreateRamp (True)
    Dim pFSymbol As ISimpleFillSymbol
    
    ' Create UniqueValue renderer and QI RasterRenderer
    Dim pUVRen As IRasterUniqueValueRenderer
    Set pUVRen = New RasterUniqueValueRenderer
    Dim pRasRen As IRasterRenderer
    Set pRasRen = pUVRen
    
    ' Connect renderer and raster
    Set pRasRen.Raster = pRaster
    pRasRen.Update
    
    ' Set UniqueValue renerer
    pUVRen.HeadingCount = 1 ' Use one heading
    pUVRen.Heading(0) = "All Data Values"
    pUVRen.ClassCount(0) = NumOfValues
    pUVRen.Field = FieldName
    Dim I As Long
    Dim pRow As IRow
    Dim LabelValue As Variant
    For I = 0 To NumOfValues - 1
        Set pRow = pTable.GetRow(I) 'Get a row from the table
        LabelValue = pRow.Value(FieldIndex) ' Get value of the given index
        pUVRen.AddValue 0, I, LabelValue 'Set value for the renderer
        pUVRen.Label(0, I) = CStr(LabelValue) 'Set label
        Set pFSymbol = New SimpleFillSymbol
        pFSymbol.Color = pRamp.Color(I)
        pUVRen.Symbol(0, I) = pFSymbol 'Set symbol
    Next I
    
    ' Update render and refresh layer
    pRasRen.Update
    Set pRLayer.Renderer = pUVRen
    pMxDoc.ActiveView.Refresh
    pMxDoc.UpdateContents
    
    ' Clean up
    Set pMxDoc = Nothing
    Set pRLayer = Nothing
    Set pUVRen = Nothing
    Set pRasRen = Nothing
    Set pRamp = Nothing
    Set pFSymbol = Nothing
    Set pRaster = Nothing
    Set pRLayer = Nothing
    Set pMap = Nothing
    Set pBand = Nothing
    Set pBandCol = Nothing
    Set pTable = Nothing
    Set pRow = Nothing
End Sub