1. First, we open the settings, enter the settings interface, find the Apple ID and icloud options at the top, as shown in the figure, and then select iCloud in the next interface.

2. We can see applications that use iCloud, such as photos, emails, address books, calendars, etc. We select the first photo here and click enter.

3. You can see that our current iCloud photo gallery is open, indicating that the iCloud backup function is working normally, and then check Download and keep the original text below. At this time, the photos in the mobile phone are all original pictures, and iCloud is only used as a backup.

When we open the photos, we can see that although the photos have been synchronized at present, we can't feel any change, because the local photos are all original pictures.

5. Then, let's change the selected option and select Optimize the storage space of iPhone. This option enables us to save the storage space of the iPhone itself.

6. When we open the photo again, we can see that there will be a small button that was loaded when we opened it, and before the loading is completed, the photo has been blurred, which shows that the storage space of iPhone is optimized, and the original image will be loaded only when we open a photo.