Nowadays, we consider it completely normal that when we install a new word processing program that we do not have to tell the computer what type of mouse we are using. However, as those of us who remember the first mice under DOS, will know that then this was certainly not the case. Only once APIs (Application Programming Interfaces) for device classes at operating system level were introduced was the separation of applications software and hardware possible.
Put in simple terms, DirectX is the umbrella term for a number of APIs that describe audio and video data streams under Windows. Since Windows 98, DirectX has established itself as a standard for multimedia orientated image processing. Using this technology, any image acquisition software product can work together with any multimedia camera, for example.
Metrology orientated image processing, on the other hand, is known for its lack of standards: Most software packages only work with a small selection of frame grabbers, which in turn, only work with a limited number of cameras. Do not forget, our goal is to "merely" get the contents of the CCD chip (that is in fact a memory chip) into the main memory of the computer.
As of version 8, DirectX does actually offer APIs that fulfill these requirements. The APIs for image streams are brought together in Windows under the name of DirectShow. So that any image creating hardware (for example, FireWire cameras) is recognized by DirectShow, it is necessary that a so-called WDM stream class driver is available (WDM = Windows Driver Model).