To scan a QR code from a picture, the process depends on the device being used: On an iPhone:

1. Save the picture or screenshot of the QR code to your Photos app.
2. Open the Photos app and view the image with the QR code.
3. Long press the QR code in the image. A menu should pop up with options such as "Open in Safari" or "Copy Link."
4. Tap the option to open the link in a browser.

On an Android device:

1. Open the gallery and find the image with the QR code.
2. Use Google Lens if available by tapping the Lens icon or open the Google Lens app and select the image.
3. Once the QR code is recognized, a link will appear which you can tap to access the content.
4. Alternatively, Samsung users can use Bixby Vision on the image to scan the QR code.

If these built-in options are not available, third-party QR code scanner apps can scan QR codes from images by uploading or selecting the image within the app. In summary, the key is to open the image of the QR code in a photo app or gallery, then use the device's native scanning feature or a third-party app to recognize the QR code and access the content.