Basler A302f User Manual

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Basler A302f User Manual Manual pdf 34 page image

Operation and Features3-18 BASLER A302fDRAFT3.10 Color Creation in the A302fcThe CCD sensor used in the A302fc is equipped with an additive color separation filter known asa Bayer filter. With the Bayer filter, each individual pixel is covered by a micro-lens which allowslight of only one color to strike the pixel. The pattern of the Bayer filter used in the A302fc is shownin Figure 3-14. As the figure illustrates, within each block of four pixels, one pixel sees only redlight, one sees only blue light, and two pixels see only green light. (This combination mimics thehuman eye’s sensitivity to color.)Figure 3-14: Bayer Filter Pattern on the A302fcWhen an A302fc is operating in a color output mode, each pixel goes through a two stepconversion process as it exits the sensor and passes through the camera’s electronics.In the first step of the process an interpolation algorithm is performed to get full RGB data for thepixel. (Because each individual pixel gathers information for only one color, an interpolation mustbe made from the surrounding pixels to get full RGB data for an individual pixel.)Since the 1394 Digital Camera Specification requires that color information be transmitted asYUV, the second step of the process is to convert the RGB information to YUV. The conversionalgorithm uses the following formulas:Y = 0.3 R + 0.59 G + 0.11 BU = -0.168 R - 0.33 G + 0.498 BV = 0.499 R - 0.421 G - 0.078 BHorizontal ShiftRegisterGRRRGGGBGGBBRGRRGGGBGGBBRGRRGGGRRRGGGBGGBBRGRRGGGBGGBBRGRRGGGR G RG BGBGR G RGR G RG BGBG BGBGR G RG BGBGR G RGR G RG BGBG BGB