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"Less Megapixels = Better Color"...

Started Oct 9, 2018 | Questions thread
Tom Schum
Tom Schum Forum Pro • Posts: 13,282
Re: "Less Megapixels = Better Color"...

Truman Prevatt wrote:

However, when a CFA is involved - interpolation is involved. A CFA camera of X MP does not collect X MP of each color. It collects X/2 MP green and X/4 MP of red and blue. The X MP RGB is interpolated. There will be a loss from this process. This is equivalent to coherent vs. non-coherent integration in RF processing.

Interpolation can take place at the intersection of the color filters, to make a resultant pixel in an output image. If you do it this way, each intersection point is surrounded by one red, one blue, and two green filters. In a 10mp Bayer sensor there are 10 million intersection points so you can make a 10mp image that holds full colorimetry for each resultant pixel.

The weakness is that each of the color filters is used in the construction of four resultant pixels, so ultimate sharpness is a problem with color filter array images.

One way to reduce this problem is to downsize to 1/4 original pixels.

Here are some images that have been downsized to 1/4 original pixels. They all look pretty good to me:

https://www.dpreview.com/galleries/1438043515/albums/d-cox-process

Not only does the downsizing remove or vastly reduce interpolation artifacts, it also reduces pixel noise by a factor of 2x.  In other words, fewer megapixels make better color, except the downsizing is more than just a reduction in megapixels, as explained above.

Nothing is simple anymore.

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