您好,
因为你的描述中没有更多关于你的窗体实现的细节,所以我假设您使用image控件显示图片,在我的项目中,包含很多PNG图片,在Button控件中使用Image控件
<Button x:Name="ToolStripButtonOpen" Click="ToolStripButtonOpen_Click">
<Image Source="Images\Open.png" Stretch="None"/>
</Button>

如上图所示,显示效果一致,可能的原因是您的控件有自己的渲染模式,因此显示效果有差异。
<THE CONTENT IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS OR IMPLIED>
Thanks
MSDN Community Support
Please remember to "Mark as Answer" the responses that resolved your issue. It is a common way to recognize those who have helped you, and makes it easier for other visitors to find the resolution later.