It looks straightforward, but should you tick the Resample Image box? What does it do to the image? Is it important? For example, if you load a photograph or other image, there is an option to Adjust Size on the Tools menu. It is a viewer for a wide range of files, including photos and other images, PDF files and more. It even has some image editing capabilities too. Preview is a useful tool on the Mac and is perhaps one of the most used. Should you resample or resize in Preview or other photo editor? When you need to resize a photo or image for printing or the web, there are several options and the wrong one can ruin it.