Hi Peai Chun,

In order to achieve this, you will need to modify the whole template for the RibbonGroup. You can find the template definition in the following file:

C:\Program Files (x86)\Infragistics\2017.2\WPF\DefaultStyles\Ribbon\RibbonGeneric.xaml

I have also attached a sample that demonstrates how you can accomplish this. In the CustomRibbonGroup.xaml file in my sample, I have made the following modifications to the default template we provide:

<!-- Image Modification -->
<!--<TextBlock x:Name="PART_Caption" Text="{TemplateBinding Caption, Converter={StaticResource stringWithoutMnemonicsConverter}}" Grid.Row="1" Margin="5,0,5,3" VerticalAlignment="Bottom" HorizontalAlignment="Stretch" TextTrimming="CharacterEllipsis" igWindows:ClippedTextToolTipService.ShowToolTipWhenClipped="True" igWindows:ClippedTextToolTipService.ToolTipStyleKey="{x:Static igRibbon:XamRibbon.ToolTipStyleKey}" TextAlignment="Center" Foreground="{DynamicResource {x:Static igRibbon:RibbonBrushKeys.RibbonGroupCaptionTextFillKey}}" />-->
<StackPanel Orientation="Horizontal" Grid.Row="1" Margin="5,0,5,3" VerticalAlignment="Bottom" HorizontalAlignment="Center">
    <TextBlock x:Name="PART_Caption" Text="{TemplateBinding Caption, Converter={StaticResource stringWithoutMnemonicsConverter}}" TextTrimming="CharacterEllipsis" igWindows:ClippedTextToolTipService.ShowToolTipWhenClipped="True" igWindows:ClippedTextToolTipService.ToolTipStyleKey="{x:Static igRibbon:XamRibbon.ToolTipStyleKey}" Foreground="{DynamicResource {x:Static igRibbon:RibbonBrushKeys.RibbonGroupCaptionTextFillKey}}" />
    <Image Height="16px" Width="16px" Source="Images\igdt_folder_open.gif"></Image>
</StackPanel>
<!-- End Image Modification -->