FPGA grabber for image pre-processing without CPU loading
21 May 2014
Up to 850 Megabyte/s can be transferred from one camera to the connected frame grabber with the current version of the CameraLink specification. This, together with stable parallel data transmission, still makes CameraLink a highly reliable and robust technology for industrial use.
This high band width is often necessary, particularly in applications with colour image processing, as the colour variants of many cameras operate with a colour reconstruction of monochrome pixels based on Bayer filters. This allows reconstruction of the original colours, which does however require highly complex algorithms in part. The band width of the image data increases up to three-fold as one colour pixel is calculated from one or more monochrome pixels.
There are two options here for a CameraLink application: with camera and frame grabbermonochrome image data can be transmitted between the camera and frame grabber and then converted offline into colour data in the CPU of the host PC, which is time-consuming and not really suitable for industrial use. The better alternative: the camera transfers monochrome image data to the frame grabber which converts these into colour values with zero latency and without loading the CPU and then transfers these as RGB data with up to a three-fold higher data rate to the host PC for easier data evaluation there.
With the currently fastest cameras some 22.5 GB/s of image data need to be reconstructed and transferred. To this purpose modern frame grabbers employ FPGA technology which is predestined for high parallel processing of large data volumes. The resources of the FPGA processor are crucial for the degree of parallelism and thus the band width of processing, but also for the algorithmic complexity of the design and hence the quality of colour reconstruction.
To manage this task, Silicon Software has further developed its intelligent frame grabbers of the microEnable 5 series for CameraLink and launched the microEnable 5 AD8-PoCL and VD8-PoCL models. Next to a link for the full configuration of CameraLink, these models include a high performance FPGA processor of the Xilinx Virtex 6 series, a memory of up to 1 GByte and a PCI Express x8 generation-2 interface to the host PC, which provides a bandwidth of 3.6 GB/s using DMA3600 technology. This enables conversion of the full bandwidth of a high-speed camera and safe transfer. Analysis software installed on the host PC for further calculations is thus relieved through the possible pre-processing on the frame grabber.
With this high performance technology, the Silicon Software frame grabbers allow numerous applications with colour processing in a host of industrial areas, for example, the printing industry, foods and agricultural engineering, the inspection of colour foils for flat-bed screens, the inspection of printed circuit boards, semiconductors and electronics, as well as the inspection of continuous materials and surfaces. The applications also benefit from the integrated colour processing and higher output speeds in the field of high- speed recording, which can achieve a frame rate of up to 425 frames/s at full HD resolution.
Whereas the microEnable 5 AD8-PoCL frame grabber was conceived specifically for image capture and image pre-processing, the FPGA of the microEnable 5 VD8-PoCL can be used for real-time image processing. Programming is via the graphic environment of the Silicon Software VisualApplet. The libraries provided there include function operators which allow individual colour processing for real-time applications. Based on these advanced technologies, colour processing is today no longer a question of magic.
The frame grabbers of the microEnable 5 series are suitable for use with all CameraLink line and area scan cameras available from STEMMER IMAGING, for example, the Piranha 4 and Linea models by Teledyne DALSA, the JAI Spark SP- 20000C or the Vieworks cameras VC-12MC and VC-25MC. These frame grabbers develop their full potential in combination with the Common Vision Blox software environment.