Enlarge photos to fit previews and slide shows: Check this box to have Photo Mechanic enlarge images that are smaller than the preview window or the slide show window. The preview may look blurry. Images that are bigger than the workspace will always be reduced for display. 

Wrap-around to beginning/end when advancing to next/previous window: Allows the arrow keys to navigate in a loop from the last photo to the first or the first to the last. 

Show Soft-rotation indicator: Displays a small rotation icon to designate that an image has been soft-rotated from its original orientation. 

Auto-center thumbnails in thumbnail gallery: Centers the selected previews in the thumbnail gallery.

Sharpen Previews: Displays previews with sharpening at a slight cost in processing speed.

Edit/Preview: The double-click options control what happens when you double-click a thumbnail in a contact sheet. You can choose to open the preview window OR to open the default external editor for that filetype.

Close preview window when editing a photo externally: When you are viewing an image in the preview window, you can choose to open it in an external editor. This option means the preview window will automatically close if you do so. Photo Mechanic will remain open.

Always make current Preview visible in Contact Sheet: With this option checked, when you advance through images in the preview window, the contact sheet will automatically scroll to reflect your navigation. When unchecked, the Contact Sheet will remain static.

Synchronize single selection between Preview and Contact Sheet: You can uncheck this option if you want to keep a single image selected in a contact sheet while you advance through images in the preview window.

Rescan Contact Sheet when Preview closes: When checked, Photo Mechanic will rescan the folder(s) in the current contact sheet when the preview window is closed. This ensures you have the most up-to-date view of your files. 

Background Colors: Choose colors for the background of the preview window.