Type the image name of your choice, and click the Save button (or COMMAND + S on the keyboard).Now, click File on the menu bar and select Save As.(You may need to scroll down.) Select a desktop picture from one of the available categories: Dynamic Desktop: These pictures change gradually throughout the course of the day based on your current location. If the file size is still large for your needs, pick a smaller resolution or smaller dimensions. On your Mac, choose Apple menu > System Settings, then click Wallpaper in the sidebar. The actual image of the size will change as you are setting lower or higher values in the Image Dimensions section. To replace the icon on an existing volume or other kind. 2: From Top menu options, Click on View > Show View. Click the small icon in the upper-left corner and press Command-C to copy it. Steps for Change Folder Thumbnail Icon or image size on Finder from Mac and MacBook 1: Open Finder on Mac. Note: Take a look at the Resulting Size section. Choose File > Get Info (or press Command-I). If you know what exactly dimensions you need for Height and Width, set them accordingly as well, and click OK.Change the Resolution first – that will significantly reduce the image size.

Now a pop-up window will open up where you can set the Resolution, Width, and Height of your image, as well as the measurement units for its size (pixels, millimeters).Once the image loads up in Preview, click Tools on the menu bar and choose Adjust Size.Navigate to the photo you want to reduce, and click Open.While in the Preview app, click on File menu and choose Open.Go to Applications and launch the Preview app (you may also start it from the dock if Preview is there).

How to change size of image on mac