Today’s Question: You mentioned that “most” digital cameras only capture one color value for each pixel. Does that mean there are cameras that capture all three color values for each pixel? If so, would such a camera provide better image quality?
Tim’s Quick Answer: There are cameras that record full-color for every pixel. The only example I know of would be Sigma cameras with a Foveon sensor. However, my testing has shown that these sensors provide inferior image quality compared to other camera models.
More Detail: It would be reasonable to assume that an image sensor that records all three color values (red, green, and blue) for each pixel would provide superior image quality compared to an image sensor that only captures a single color value for each pixel. However, in my experience that is not a reasonable assumption.
The first time I tested a camera with a full-color Foveon sensor was in 2002. The initial tests were impressive, but this was also very early in the context of digital photography. I anticipated at the time that these full-color sensors might be the wave of the future. I was wrong.
More recently I had the opportunity to test a camera with a Foveon sensor, and I was quite disappointed. The captures were among the noisiest I had ever seen, regardless of the ISO setting used.
While it may seem unbelievable that a camera that records only a single color value for each pixel would produce photos of high quality, the reality is that this approach works quite well. Put simply, stacking up multiple photodiodes for each pixel actually diminishes quality more than the processing required to create a full-color image from a capture where only one color value is recorded for each pixel.
What all of this means to me is that the underlying technology is less important than the actual results you can achieve. When it comes to image sensors in today’s digital cameras, a sensor that records only one of three (red, green, or blue) color values for each pixel is capable of producing excellent image quality, even compared to sensors that record all three color values for each pixel.