Here’s how to enable the macOS’s built-in Markup editing toolkit for more apps: How to enable Markup extension for other apps? And you can keep the image in photos library, export it or share it with your contacts. Once you finish editing, click Save Changes > Done in the upper right corner. There are multiple brush and pen options, as well as shape tools, line thickness adjustments, a text tool and font adjustments, and color options for each markup. You can use the tools that appear in the upper right corner to edit the selected image. Then you click the Extensions button in the bottom right corner and select Markup from the Extensions popup menu list. You need to open the Photos app, choose the image you want to edit, and click the Edit button in upper right corner of the toolbar. In the Preview app, you can press Shift – Command – A to directly show or hide the Markup tools, while in the Photos app, this feature is hidden in the app’s extensions interface. Well, the Markup extension is available around the whole system. Some Mac beginners may try to find the markup extension in Photos app. How to access Markup in Photos app on Mac? If you frequently edit photos on your iPhone, you may have been very familiar with the Markup feature in Photos app, but do you ever use the Markup extension on your Mac? This hidden feature offers many simple but handy tools, allowing you to annotate an image, add a signature to it, or simply resize a picture in most third party Mac apps.