XnRetro is a free portable tool for tweaking photos with assorted retro filters, lighting effects, frames and more.

There's no adware, no nag screens, no pop-up browser windows opening at the developer's site - just unzip it and go.

The interface is simple and straightforward. Open an image, select the type of effect to apply - Retro, Light, Vignette, Frame - and you're presented with thumbnails illustrating the results. Click one and it's applied to the preview window.

If you're not sure what to try, pressing the left or right arrow steps you through each effect in turn. Keep going until you find something you like.

Fine-tuning options include sliders to tweak brightness, contrast, gamma, exposure, saturation, red/ green/ blue balance, noise, vignetting or light opacity.

The final image may be saved as a JPG or PNG file, or shared directly via Flickr, Facebook, Picasa, email, and a host of image sharing sites.