Analysis of CCD used in ES-1000

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As I searched CCD information on WWW, I was able to find a page of data sheets of CCD area sensors on the WWW server of Sony America. Among various CCDs shown here, ICX054AK is 1/3 inch large and has 270K pixels which matches with the catalogue spec of ES-1000/DC-20. So I wrote a decoder expecting that this CCD is used in ES-1000/DC-20. As it worked properly, I assume here that ICX054AK is the CCD used.

I would sincerely welcome objections to this assumption if you will name the alternative CCD :-).

Summary of Specs

Detailed specs are in the data sheet in PDF format.

Output format

Physically, this CCD consists of the color filter array of Ye (yellow), Cy (cyan), Mg (magenta), and G (green). They are aligned as shown left.

But we can't obtain data of each pixel separately; actual output data is calculated by adding two adjacent lines vertically as shown left.

We can represent this output in RGB as shown left by substituting Ye = R + G, Cy = G + B, and Mg = R + B.

This format looks rather complicated; the point is that we can obtain 2R+3G+2B (which can be used as luminosity) by adding any two horizontally adjacent signals.

How to decode this output

After trials and errors, I found that following principles should be kept: Based on these principles, cmttoppm decodes CCD data as follows (a sample data is attached in which signal 1 is 2R+G+B, signal 2 is 2G+B, and signal 3 is R+2G):
  1. CCD data itself is used as signal 1.
  2. Calculate signal 2 by horizontal interpolation.
  3. Calculate signal 3 by vertical interpolation.
  4. Generate R, G, and B from signal 1, 2, and 3.
  5. Perform several postprocessing operations including Gamma correction.
Critics and improvements to this method is welcome.

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