User manual

Running the Demonstration
XAPP794 (v1.3) December 20, 2013 www.xilinx.com 26
(Daylight, Cool White Fluorescent, U30, and Incandescent sources) with the color correction
matrix set to Bypass (no color corrections applied). Average values for the 24 patches at each
illumination setting were calculated by a MATLAB® software script. A second script is used to
model the Xilinx color correction matrix operations and determine a set of coefficients that
result in output from the color correction matrix that best matches the known target values for
the 24 patches. The MATLAB software scripts used to develop the coefficients for the Color
Correction Matrix IP core are included in the 1080p60 camera image processing design files
(xapp794.zip) that can be downloaded from the Application Notes link on the ZVIK 2013.2
documentation page. Additional information on development of the color correction coefficients
can be found in an article titled Image Sensor Color Calibration Using the Zynq-7000 SoC in the
Xcell Journal [Ref 2].
Figure 24 illustrates the effects of white balance on the 24-patch ColorChecker chart for the
four different illumination sources:
The top four images show the output of the image sensor and image processing pipeline with
no color correction applied for four different illumination sources. There are marked differences
in color for all four cases. The bottom images show the output with the various color corrections
applied for each different illumination source and illustrate how the white balance setting
corrects the colors. These images were taken in the X-Rite Macbeth Judge II light booth using
the ZVIK camera design.
Xilinx provides support for the 1080p60 camera image processing reference design, IP cores
such as the Color Correction Matrix, and Xilinx FPGA and SoC products. Xilinx cannot provide
assistance to customers developing color correction coefficients for the ON Semiconductor or
any other image sensor. Development of custom color correction coefficients is the
responsibility of the customer. The MATLAB software scripts are provided as examples to
assist customers in developing their own color corrections for different image sensors. Consult
the Additional Resources tab of the ZVIK product page
for additional information.
X-Ref Target - Figure 24
Figure 24: White Balance Color Checker Results
Daylight
Uncorrected
Corrected Corrected Corrected Corrected
Uncorrected Uncorrected Uncorrected
Cold White Fluorescent U30 Incandescent
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