I'm very often checking individual images. And for that purpose ToyViewer is a much better choice than Preview.

By default it shows images in their original resolution. That's how i want it. You can however, if you prefer, make ToyViewer adjust larger images to your display size (a bit hidden in the preferences - note to the developer: i think that option should be moved to the main menu).

Clicking *Alt + CMD + Z* gives you a borderless "foreground" mode: you can scroll through larger images or move through them with a hand tool. Nice! At the bottom of the image viewer is a black button to view your image in full screen/ match screen mode. There is a rectangle selection feature - hitting that black button will change your selection to borderless full screen. Very nice!

As well there is a scaling option at the bottom of the image viewer.

My only suggestions for improvements:
A short key for that *match screen* button because i'm using a multi-button mouse and assigning such a short key to one of the buttons would speed up my work flow. ToyViewer's short key for toggling windows is *CMD + 0* while most other apps are using *CMD + for that.

Despite these minor issues a 5 stars program. It has as well a host of exporting and editing options but when i'm honest, i hardly used those and would start Photoshop instead.