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The better white balance

12 April 2022 – SVCam Products
The better white balance
© SVS-Vistek

In the process of industrial quality control, the mono camera is still the predominant camera type. Increasingly, color cameras of higher resolution are also being used. Here, the limited color reproduction of an industrial camera is often a major obstacle. With the Color Transformation Control Feature, the FXO series from SVS-Vistek offers a procedure that goes far beyond the possibilities of RGB matching in white balance.

Color representation for Industrial cameras

Current color cameras generate the color impression on the image sensor with the filter pattern applied to the sensor, usually a Bayer pattern. Ideally, these filters should have parameters that are difficult to reconcile, such as high edge steepness, high transparency in the desired wavelength range and high absorption in the undesired wavelength range, as well as low side densities. The transparency maxima are preferably arranged in such a way that the color impression of the human eye is also reproduced. Ideally, the RGB channels should also be identical and highly sensitive. These wishes cannot currently be implemented in a sensor. A color representation of a sensor is always a compromise between these and other limitations.

Standard RGB amplification to the same level is old standard (© SVS-Vistek)

The white balance

The easiest way to get a "color correct" image is to adjust the gain of the RGB channels so that the colors are weighted equally. For this purpose, the amplification of red, green and blue is set in such a way that a grey/white point reflects all three colors with the same intensity.

The density curves of the RGB color filters are not ideal and show side densities in the other two colors. These side densities are not taken into account in the RGB adjustment. However, the poor spectral quality of the filters is the main reason for the inferior color display of industrial cameras.

A correct white balance in terms of color temperature is the cornerstone for any color reproduction (© SVS-Vistek)

The FXO camera series with Color Transformation Control Feature

The FXO can do more in terms of color correction: A matrix operation on each individual pixel calculates the colors in such a way that a significantly improved color representation can be achieved. This matrix operation takes place in real time on the camera's FPGA and includes the side densities.

The calculation matrix is freely definable. In order to cover standard situations quickly, some situations are already predefined. Of course, these always refer to the respective sensor of the camera. Among others, the typical light situations D50 and D65 (daylight with 5000 and 6500 Kelvin, respectively) are predefined.

The FXO series can do more

The FXO series is our current performance series in the field of C-mount cameras. The latest sensors such as the Sony Pregius S sensor are read out with state-of-the-art hardware and firmware. The Color Transformation Control Feature is just one of the exciting features of this camera series, the image quality is the reference. The FXO series shines with highest frame rates and advanced 10GigE and CoaXPress-12 interfaces.

copyright title image: © SVS-Vistek

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