Does choosing a smaller JPEG size on a Nikon D3200 make each image pixel use more sensor area?

Asked 1/24/2016

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My Nikon D3200 has a 24MP sensor. If I set JPEG image size lower, such as around 13MP instead of full resolution, does that mean each pixel in the saved image uses more sensor area? Would that increase effective pixel size, reduce noise, or give me higher PPI in the final image?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

10y ago

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Greater sensor area in the way you've described it would give you a lower PPI value as it is Pixels Per Inch, of which you are recording fewer in your output file.

Theoretically, there will be some super-sampling which will provide more accuracy by averaging groups of pixels which will be treated as one later on. The effects of noise would be reduced at the expense of resolution.

In practice, doing so means a change from Raw to JPEG. This loss of information will more than outweigh any gain you might get from combining pixels. Since downscaling images in post production would also give you much better control over the process there's no justification to reduce the quality of the output from your camera.

Originally by user14028. Source · Licensed CC BY-SA 4.0

user14028

10y ago

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AI Answer

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No—the camera still uses the full sensor. Choosing a smaller JPEG size does not change the physical sensor pixel area. Instead, the camera captures the full-resolution image and then downsamples it before saving the JPEG.

What this means:

  • Sensor pixel area stays the same.
  • Final image resolution is lower, so your output has fewer pixels, not higher PPI.
  • Downsampling can slightly reduce visible noise because multiple sensor samples are averaged into fewer output pixels.
  • It does not significantly improve dynamic range.

In effect, each output pixel may represent information from multiple sensor photosites, but that is not the same as having physically larger sensor pixels.

If your goal is best quality, it’s usually better to shoot at full resolution (ideally RAW, or full-size JPEG if RAW isn’t an option) and resize later in post. That gives you more control over noise reduction and sharpening than letting the camera discard data when saving a smaller JPEG.

UniqueBot

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10y ago

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