高动态范围(High Dynamic Range) ( HDR ) 视频(video)技术是再现肉眼所见的颜色以及最亮白色和最暗黑色之间的对比度的下一个重大飞跃。HDR视频是关于从相机到后期制作再到分发和显示，重新创建图像真实感。在这篇文章中，我们将介绍Windows 10(Windows 10)升级后您无法重新启用Stream HDR视频开关的问题的解决方案。
让我们看一下您可能会遇到此问题的典型场景。
在早期版本的Windows 10中，您关闭Stream HDR 视频开关(Stream HDR video switch)，然后进行升级。在这种情况下，您无法重新启用Stream HDR video 开关(Stream HDR video switch)以流式传输高动态范围 ( HDR ) 视频。
打开 Stream HDR 视频开关
如果您在升级Windows 10后遇到无法重新启用(Windows 10)Stream HDR视频开关的问题，您可以尝试以下两种推荐的解决方案之一，看看是否有助于解决问题。
- 返回到以前版本的Windows 10
- 修改注册表以启用Stream HDR视频开关
让我们看一下列出的每个解决方案所涉及的过程。
1]返回到以前版本的Windows 10
如果您在过去 10 天内升级到较新版本的Windows 10 ，您可以通过将设备恢复到您升级的(Windows 10)Windows 10版本、打开流 HDR 视频开关(Stream HDR video switch)，然后升级到较新的 Windows 来解决问题又是10版。
要返回之前的 Windows 10 版本，请执行以下操作：
选择“开始(Start)” > “设置” (Settings ) > “更新和安全(Update & Security)” > “Recovery > “返回到 Windows 10 的上一版本”(Go back to the previous version of Windows 10 )标题下 的“开始 使用”。(Get started )
此过程将保留您的个人文件，但会删除升级后安装的应用程序和驱动程序，以及您对设置所做的任何更改。
在之前的Windows 10版本中(Windows 10)打开 Stream HDR 视频开关后，您可以检查更新(check for updates)以重新安装较新的Windows 10版本。
如果此解决方案不适合您，请继续下一个解决方案。
2]修改(Modify)注册表以启用Stream HDR视频开关
如果您不再可以选择将Windows 10还原到以前的版本，则可以尝试此解决方案。您可以通过修改注册表来启用Stream HDR 视频开关。(Stream HDR video switch)
就是这样：
由于这是注册表操作，建议您备份注册表(back up the registry) 或 创建系统还原点 ，以防过程出错。采取必要的预防措施后，您可以进行以下操作：
- 按Windows key + R调用“运行”对话框。
- 在“运行”对话框中，键入cmd，然后按CTRL + SHIFT + ENTER以在管理员模式下打开命令提示符(open Command Prompt in admin mode)。
- 在命令提示符窗口中，复制并粘贴下面的命令，然后按 Enter(Enter)。
reg add “HKCU\Software\Microsoft\Windows\CurrentVersion\VideoSettings” /v EnableHDRForPlayback /t REG_DWORD /d 1
- 退出命令提示符(Command Prompt)窗口，然后重新启动Windows 10设备。
启动时，您可以检查更新以重新安装较新的Windows 10版本。
高动态范围 (HDR) 视频
从技术上讲，HDR视频标准不仅仅包含更高的峰值亮度和更低的黑电平。HDR还支持更广泛的调色板、新的传输函数、更大的位深度以及静态和/或动态元数据。
以下是HDR视频技术的工作原理：
- 创造更清晰的对比和更丰富的色彩
- 增加动态范围（又名峰值亮度和黑电平）
- 扩展(Expands)色彩空间（广色域）
- 提高图像保真度（10 位色深和 1024 色度）
- 更新光电传递函数
- 提供静态和动态元数据
相关阅读：(Related read: )解决 Windows 10 中常见的 HDR 和 WCG 颜色问题。
Enable the Stream HDR video switch after Windows 10 upgrade
High Dynamic Range (HDR) video technology is the next great leap forward to reproducing what the naked eye sees in colors and contrast between the brightest whites and the darkest blacks. HDR video is about recreating image realism from the camera through postproduction to distribution and display. In this post, we will present the solution to the issue whereby you’re unable to re-enable the Stream HDR video switch after Windows 10 upgrade.
Let’s take a look at a typical scenario where you can encounter this issue.
In an earlier version of Windows 10, you turn off the Stream HDR video switch and then upgraded. In this scenario, you can’t re-enable the Stream HDR video switch to stream high-dynamic-range (HDR) videos.
Turn on the Stream HDR video switch
If you’re faced with this issue whereby you’re unable to re-enable on the Stream HDR video switch after a Windows 10 upgrade, you can try either of the two recommended solutions below and see if that helps to resolve the issue.
- Go back to the previous version of Windows 10
- Modify the registry to enable the Stream HDR video switch
Let’s take a look at the procedure involved concerning each of the solutions listed.
1] Go back to the previous version of Windows 10
If you upgraded to a newer version of Windows 10 within the last 10 days, you can resolve the issue by restoring the device to the version of Windows 10 you upgraded from, turn on the Stream HDR video switch, and then upgrading to the newer Windows 10 version again.
To go back to your previous version of Windows 10, do the following:
Select the Start > Settings > Update & Security > Recovery > Get started under Go back to the previous version of Windows 10 heading.
This process will keep your personal files, but it’ll remove apps and drivers installed after the upgrade, as well as any changes you made to settings.
Once you’ve turned on the Stream HDR video switch in the previous Windows 10 version, you can check for updates to reinstall the newer Windows 10 version.
If this solution doesn’t work for you, continue with the next solution.
2] Modify the registry to enable the Stream HDR video switch
You can try this solution if you no longer have the option to restore Windows 10 to a previous version. You can enable the Stream HDR video switch by modifying the registry.
Here’s how:
Since this is a registry operation, it is recommended that you back up the registry or create a system restore point in case the procedure goes wrong. Once you have taken the necessary precautionary measures, you can proceed as follows:
- Press Windows key + R to invoke the Run dialog.
- In the Run dialog box, type cmd and then press CTRL + SHIFT + ENTER to open Command Prompt in admin mode.
- In the command prompt window, copy and paste the command below and hit Enter.
reg add “HKCU\Software\Microsoft\Windows\CurrentVersion\VideoSettings” /v EnableHDRForPlayback /t REG_DWORD /d 1
- Exit the Command Prompt window, and restart your Windows 10 device.
On boot, you can check for updates to reinstall the newer Windows 10 version.
High Dynamic Range (HDR) video
Technically speaking, HDR video standards encompass more than just higher peak brightness and lower black levels. HDR also supports a wider color palette, new transfer functions, greater bit depth, and static and/or dynamic metadata.
Here’s how HDR video technology works:
- Creates more-defined contrasts and richer colors
- Increases dynamic range (aka, peak brightness and black levels)
- Expands color space (wide color gamut)
- Improves image fidelity (10-bit color depth and 1024 color shades)
- Updates to an optoelectronic transfer function
- Offers static and dynamic metadata
Related read: Troubleshoot common HDR and WCG color problems in Windows 10.
