Digital photography is fun. Digital photography would be even more fun without those reiterative exposure problems. Annoyingly they occur especially in situations, where light is most beautiful - for instance on days with crystal clear air, cloudless sky and bright sunshine. Digital cameras simply can't cope with the very intensive interplay of light and shadow. Consequences are overexposure in light image areas and/or strong noise in dark areas. "Correct" exposure is often impossible.
Cause for this nuisance is the technical imperfection of todays digital cameras. A thing the human eye manages effortlessly - the clean visualization of even the greatest intensity differences without "overexposure" or "noise" - is utterly impossible for a digital camera.
|Exposure series and the result of HDR processing with FDRTools|
The following consideration shows a way out of this unsatisfying situation: what is impossible with one image, can be accomplished with several, differently exposed images. This way all areas of a scene are present optimally exposed, though in different images. The "only" thing one needs to do now is to combine these photos to a single image in a way that lets overexposure and noise disappear.
Such an image is named HDRI (High Dynamic Range Image). An HDRI comprises all information contained in the images of an exposure series. Normal output devices like monitor or printer can not reproduce the information content of an HDR image in a natural looking way. An other step - named Tone Mapping - is needed to make this possible. Tone Mapping converts an HDRI to an LDRI (Low Dynamic Range Image) preserving all relevant details of the scene. The LDRI can then be displayed using monitors and printers.
The figure to the left shows an example for such an exposure series and the tone mapped result obtained with FDRTools.
|Result of a dramatising image processing with FDRTools|
The tone mapped image resulting from combining three images as shown above looks quite natural. However, achieving dramatising effects with FDRTools is also possible. The premium tone mapping method named Compressor with ease converts boring looking scenes into exciting images.
But there is more to merging images than just scene HDRI and TM. FDRTools offers a method named Creative. Creative allows for mixing images with completely differing content thus broadening the possibilities of HDR imaging and supporting creative photography.
One of the essential functions of FDRTools is to merge the images of an exposure series into a so called HDR image. When doing such an exposure series you should observe the following: