Common.Wpf/Toolbar/ImageButton.xaml

<Button x:Class="Common.Wpf.Toolbar.ImageButton"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        mc:Ignorable="d"
        d:DesignHeight="20"
        d:DesignWidth="20">
    <Button.Resources>
        <Style TargetType="{x:Type Image}"
               x:Key="toolbarImageStyle">
            <Style.Triggers>
                <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType={x:Type Button}, AncestorLevel=1}, Path=IsEnabled}"
                             Value="False">
                    <Setter Property="Opacity"
                            Value="0.25" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Button.Resources>
    <Image x:Name="image"
           HorizontalAlignment="Center"
           VerticalAlignment="Center"
           Style="{StaticResource toolbarImageStyle}" />
</Button>