When you have the Finder view set to column display, the last column in a Finder window displays a preview of a selected file. When that file is an image file, you will see a thumbnail of the image.
It's nice to be able to quickly see what an image looks like, but if you want to see any details in the image, you'll have to open the file in an image editing application. Or will you?
One nifty Finder feature that is often overlooked is the ability to zoom in, zoom out, and pan around an image when in column view.
Zoom and Pan Finder Image Preview
Open a Finder window and select the column view button at the top of the window, or select As Columns from the Finder's View menu.
Once in column view, navigate to an image you wish to display. When you select the image, a thumbnail view will appear in the last column.
Hold down the option key and click on the thumbnail. The cursor will change to a magnifying glass. Continue to click on the image to zoom in.
To zoom out, hold down the shift + option keys and click on the thumbnail image.
To pan an image, zoom in on it, then place the cursor on the image, Click and hold, then move the cursor to pan the image.