Mac users interested in Justlooking by marc wandschneider generally download:
JustLooking is an easy-to-use image viewer that allows you to browse through your photo collections more efficiently; this handy program supports dozens of image formats, such as .JPG, .BMP, .GIF, .PNG and many other.
You will be able to change the photo's format, stretch or fit the image, send photos to trash and many other.
