Fusion is a program that allows you to combine two or more photographs, achieving a single image resulting from the fusion of the same. They do not necessarily represent a similar scenario, otherwise the application is responsible for smoothing the differences in tones and brightness of the photos.
Fusion tries, through a set of techniques, to achieve a rendering that allows to obtain images of high dynamic range (HDR). This effect can be tested by taking photographs of the same landscape at different times, with different light, sky color, etc., and then get the mixture.
It has a tool that resizes the images so that they remain the same size. After mixing and viewing the results, you can manually select several parameters (contrast, saturation of colors, sharpness, brightness, etc.) to correct the photo.
Compared with other professional software to obtain HDR images, Fusion achieves very satisfactory results, with the advantage that it is also free.
In the official site is available a short manual (in English) with basic instructions for using the program, although it does not present major difficulties.
Fusion 2.4.1 is the latest version (updated in October 2012) of this photo editor that can be downloaded for free to use with Windows (7, Vista, XP).