Camera-Internal Color Processing

Today the acquisition, processing and reproduction of color images is of increased importance for numerous industrial, medical and scientific applications. Many applications require color image acquisition and reproduction systems that enable high-color fidelity in the reproduction of live images. Thanks to the development of our own Kappa color processor for color fidelity live images in digital and video cameras, we have achieved independence for long-term customer projects! With future-oriented investments in digital technology as well as in the video domain, Kappa is a reliable camera developer that guarantees long-run customer series without the risk of discontinued external components.
 
• Digital Color Processor (DCIP) for RGB Full-Frame Sensors
Kappa digital color cameras are based on progressive scan CCD sensors with primary color filtering in a Bayer mosaic pattern (RGB). They assure high fidelity of color reproduction and enable flexible adaptation of camera-internal color processing algorithms to the application-specific spectral power distribution of light and its characteristic object spectra. Kappa color management is realized on a flexible FPGA platform with real-time image processing. Thus, we are independent of external components and suppliers. Moreover, this concept is perfect for specific adaptations and customer-specific extensions. Recently, we used our long experience with DCIP in diverse cameras and applications for the development of our own video color processor.
 

• Video Color Image Processor for Color Mosaic Sensors
The video color processor is a component of new Kappa video cameras using proven Interline-CCD sensors (PAL or NTSC) with complementary color filtering in a color mosaic (CMYG). It is principally based on the same concept as DCIP and thus offers the same advantages for flexible adaptations. The main difference from DCIP is an interpolation module for the conversion of raw sensor data into a YUV data format and adapted processing for color correction and white balance. The color artifacts at the edges, caused by interpolation, are minimized by an appropriate algorithm. Fine tuning allows you to adapt the color rendering to your needs. The optimum parameterization of each color processor and the flexible adaptation to different conditions are based on a spectral modeling of the application system. The spectral characterization of the color sensors is an essential condition for the selection and the parameterization of the algorithms for color correction and color constancy. For this, a specific color camera measuring station has been designed. The measuring station consists mainly of a stable Wolfram halogen light source, different filters for the modification of light source spectral power distribution, a step motor-driven filter wheel for the selected filter foils, and a beam splitter that enables spectral reference measurement synchronous with the acquisition of camera image data. The acquired measuring results are used for model-based optimization of the camera’s color reproduction in the application system. This approach allows the use of spectra from typical test charts – for example, the Macbeth Color Checker – as well as of characteristic objects such as tissue or other material samples to optimize the color balance of Kappa cameras for specific applications.