Capturing an image at a much higher resolution than needed for the end result is of great value in obtaining a clean and noise free result.
This oversampling is true for images just as much as it’s true for audio.
I’ve discussed the oversampling concept before, and I’m going to be publishing (in DAP) some examples soon of this important concept, because the future involves DSLRs in the 100+ megapixel range. Not for the sake of resolution alone, but for image quality.
DSLRs ought to come on the market relatively soon whose image quality will be spectacular even without downsampling to lower resolution.
But the oversampling will make possible images in the 70 megapixel range (from ~140 megapixel sensors) that will rival any medium format camera available today. Pick any numbers you like, the idea remains the same.
Sensor existence proof — Sony RX100
Even native pixels without downsampling should be excellent, the Sony RX100 being an existence proof (its main failing being a weak lens).
The Sony RX100 is a 20-megapixel camera whose sensor if scaled to full-frame DSLR at the same pixel density would be 148 megapixels. Yet its per-pixel image quality is first-rate.
Still, let’s make a point of complaining that the RX100 sensor quality is not good enough, and assume we would downsample those 148 megapixels in half (70.7% linearly) to reach 72 megapixels— would it look pretty awesome? Indeed it does.
The stitched image below is close to our theoretical size— 109 megapixels. Even on a per-pixel basis (before any downsampling), its quality is excellent, with proper ETTR exposure only making it better.
Click for a larger version.
The crop below is actual pixels from the 109 megapixel image above, showing that if we had a DSLR with simply the same per-pixel quality, it could be stunning.
The image doesn’t need downsampling to fix any quality issue (it’s already excellent). But this might not always be the case (noise, poor exposure situations, etc).
Shown below is an actual pixels crop from the 54-megapixel downsampled image (downsampled from the 109-megapixel image).