If you want to flip or mirror images then you can use the free GIMP tool. It is very easy to do so using this image editor for Windows PC.

Once installed you need to download BIMP, the Batch Image Manipulation Plugin, and install it (see Wikibooks GIMP/Installing Plugins for the details). Again, easy-peasey.

1] Use the Sharpen tool GIMP provides several picture editing, drawing, and editing tools to customize the color profile of an image, rotate it, flip it, crop it, and do more editing.

Discover Batcher, the powerful batch-editing plugin designed for GIMP 3.0. Easily convert file formats, export layers, and apply custom actions to streamline your creative workflow.