It was nearly 2 years ago to the day that Sigma unveiled its 14-megapixel SD14 DSLR at the Photokina tradeshow.

This week, the event is again kicking off in Cologne, and Sigma has used the occasion to announce a new addition to its DSLR line-up of four models.

The SD15 inherits the 14-megapixel Foveon sensor from its predecessor, but boasts improvements including a larger LCD screen and also a new processor.

First the chip - Foveon technology is unique in using stacked silicon photo-detectors (2652 x 1768 in each of the three layers).

This means it can capture all RGB colours at each and every pixel, and can therefore offer sharper resolution and more accurate colour.

But the model is also built around the new TRUE II image processing engine.

Says Sigma: "This provides high resolution power and reproduces high definition images rich in gradation and impressive three-dimensional detail".

The new launch also has a 3.0-inch LCD monitor, as compared to the 2.5-inch screen on its predecessor.

We don't have any other tech specs at the moment nor a price but the SD14 was £1099.99 when it was launched in September 2006 so perhaps we could be looking at a similar price point.