While Apple's iPhone, iPad, and the Photos apps in iOS and macOS are the standard for image acquisition and processing today, there's another way to get images into your Mac: Apple's Image Capture app.
If you have a flatbed USB scanner or a USB or WiFi multifunction printer, you can use Image Capture to acquire its scanned images.
To select where to import images to on your Mac click the Import To: popup menu, then select either one of the standard destinations, a custom folder location, or select Build web page.
When you plug a digital camera into your Mac over USB, macOS automatically loads the class driver for you so it can communicate with the device.
The reason to use Image Capture in macOS is for ingesting images from third-party cameras and scanners.
