There are a number of photo editing utilities out there, but I'm impressed with Fotor, now available for Windows Phone 8 handsets. Along with the expected filters of a photo editing app, it has more traditional sliders to deal with saturation, brightness, and contrast.

Here's two pictures showing a before and after, with a daylight shot on my Lumia 820, followed by some colour boosting and a tilt-shift effect in the resulting edited image.

The original (resized for the web)

...and the retouched version (again resized for the web)

One thing that I appreciated in the app is that it that you can save the edited image with no loss of resolution, although you do have cropping tools if you want to trim the image.

The Instagram generation will be pleased to know that they have pre-set filters that can be used, and these are handily grouped together as 'classic', 'lomo', or 'B&W' effects to make them easier to navigate.

Fotor is a free app, and you can download it from the Windows Store here.