Image Demosaicing Algorithms for WB Capture

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Image Demosaicing Algorithms for WB Capture

• Li-wei He and Ross Cutler
• CCSP
• Microsoft Research

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Bayer Pattern

• Single chip digital camera use color filter array
  (CFA) to sample colors
• One color channel per pixel
• Color plane interpolation demosaicing
• Most used CFA Bayer pattern
• Green is 2x Blue and Red

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Motivations

• General demosaicing algorithms not suitable for
  whiteboard capture
• Thin strokes cause color artifacts
• Prior knowledge may allow superresolution (?)
• Working in Bayer space allows performance gain
• Less memory footprint and CPU cycles

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Previous Works

• Class 1 interpolation each color channel
  separately
• NN, Bilinear, Cubic
• Fail in high frequency regions (edges)
• Class 2 exploit inter-channel correlation

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Previous Works
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Practical Considerations

• Consumer digital cameras often have lens acting
  as low pass filter
• Aplux camera has 70-80 resolution
• Enough to prevent aliasing in green
• Sets upper limit for improvement (?)

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