直方图将柱状图替换为面积图，优化密集数据显示效果，Y轴刻度自动取整支持 K/M 缩写，X 轴根据数据范围自动设置。

XP.Common/Controls/ImageHistogram/ImageHistogramControl.xaml

@@ -3,39 +3,58 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
              xmlns:loc="clr-namespace:XP.Common.Localization.Extensions"
+             xmlns:local="clr-namespace:XP.Common.Controls.ImageHistogram"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              mc:Ignorable="d"
              d:DesignHeight="200" d:DesignWidth="400">
+    <UserControl.Resources>
+        <local:FrequencyLabelConverter x:Key="FreqConverter"/>
+    </UserControl.Resources>
     <Grid>
         <!-- 图表控件 | Chart control -->
-        <telerik:RadCartesianChart x:Name="HistogramChart">
+        <telerik:RadCartesianChart x:Name="HistogramChart" Padding="0">
             <!-- 禁用 Telerik 自带的无数据提示 | Disable Telerik built-in empty content -->
             <telerik:RadCartesianChart.EmptyContent>
                 <TextBlock/>
             </telerik:RadCartesianChart.EmptyContent>
-            <!-- X 轴：灰度级别 | X Axis: Gray Level -->
+            <!-- X 轴：灰度级别（缩小字体，控制刻度数量，K/M 缩写）| X Axis: Gray Level -->
             <telerik:RadCartesianChart.HorizontalAxis>
                 <telerik:LinearAxis x:Name="XAxis"
                                     Minimum="0"
                                     Maximum="255"
-                                    Title="灰度级别"/>
+                                    MajorStep="64"
+                                    FontSize="9">
+                    <telerik:LinearAxis.LabelTemplate>
+                        <DataTemplate>
+                            <TextBlock Text="{Binding Converter={StaticResource FreqConverter}}"/>
+                        </DataTemplate>
+                    </telerik:LinearAxis.LabelTemplate>
+                </telerik:LinearAxis>
             </telerik:RadCartesianChart.HorizontalAxis>
 
-            <!-- Y 轴：像素频次（默认线性）| Y Axis: Pixel Frequency (default linear) -->
+            <!-- Y 轴：像素频次（K/M 缩写标签）| Y Axis: Pixel Frequency (K/M abbreviation labels) -->
             <telerik:RadCartesianChart.VerticalAxis>
                 <telerik:LinearAxis x:Name="YAxis"
                                     Minimum="0"
                                     Maximum="1"
-                                    Title="频次"/>
+                                    FontSize="9">
+                    <telerik:LinearAxis.LabelTemplate>
+                        <DataTemplate>
+                            <TextBlock Text="{Binding Converter={StaticResource FreqConverter}}"/>
+                        </DataTemplate>
+                    </telerik:LinearAxis.LabelTemplate>
+                </telerik:LinearAxis>
             </telerik:RadCartesianChart.VerticalAxis>
 
-            <!-- 柱状图系列 | Bar Series -->
+            <!-- 面积图系列（适合密集直方图数据）| Area Series (suitable for dense histogram data) -->
             <telerik:RadCartesianChart.Series>
-                <telerik:BarSeries x:Name="HistogramBarSeries"
-                                   ValueBinding="Frequency"
-                                   CategoryBinding="GrayLevel"
-                                   ShowLabels="False"/>
+                <telerik:ScatterAreaSeries x:Name="HistogramBarSeries"
+                                           XValueBinding="GrayLevel"
+                                           YValueBinding="Frequency"
+                                           Fill="#7F2196F3"
+                                           Stroke="#FF2196F3"
+                                           StrokeThickness="1"/>
             </telerik:RadCartesianChart.Series>
         </telerik:RadCartesianChart>
 
@@ -44,7 +63,7 @@
                    Text="{loc:Localization Histogram_NoData}"
                    HorizontalAlignment="Center"
                    VerticalAlignment="Center"
-                   FontSize="14"
+                   FontSize="12"
                    Foreground="#9E9E9E"
                    Visibility="Visible"/>
     </Grid>