Do bigger pixels mean less noise?

Started Jan 6, 2012 | Discussions thread
sacundim
Senior MemberPosts: 1,111
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No, they don't.
In reply to Louis_Dobson, Jan 6, 2012

Louis_Dobson wrote:

Surely it works like this:

Noise is "false" data. The larger the pixel the more "true" data (light) it collects, and the less the noise.

The thing is that, for a fixed sensor area, while fewer larger pixels collect more data per pixel , it also means that you have fewer pixels. Or conversely, more and smaller pixels may collect less data individually , but there's more of them, and that extra information can be put to two different uses:

  • Reproduce more detail;

  • Reduce noise.

The math says that when it comes to noise at a fixed scale (output size), pixel amount vs. pixel size is a wash; a larger number of pixels compensates exactly for their smaller size. What matters the most is the size of the sensor and how efficient it is per unit of area .

Another way of putting it: smaller pixels are indeed inherently more noise-prone than larger ones. But that only leads to worse whole-image noise performance if they're disproportionately noisier compared to large pixels. If the extra noise is reasonable relative to the smaller size, then the increased pixels count cancels it out.

But that's not the whole story, because more pixels = more detail. As I mentioned above, that detail can be sacrificed to lower noise, but it can also be used to make sharper, more detailed photos. So with similarly efficient sensor tech, the camera with more pixels is at an advantage because it can either produce the same detail and noise as the one with fewer (by downscaling or using noise reduction), or it can produce a more detailed image.

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