For example, you can add bokeh, and transform your image, so it looks like it's drawn with a felt pen or in the cubism style.

For example, both the width and the height must ... You have just managed to mirror an image using GIMP. And as you can tell, it is not difficult at all. GIMP does not have a mirror tool, but ...

If you already have GIMP open and you want to get the photo into GIMP, find the image and drag it into GIMP. You can also find the image and right-click on it, then choose Open with then GIMP.