I heard that bigger pixel size of sensor will get better quality, especilly noise in low light condition. if I set image size to a smaller resolution, will it affect the pixel size and improve image quality? (My camera is Sony A6000, APS-C sensor)

  • For this question to be properly answered you must define image quality. When viewed at native resolution on a monitor so the larger file is viewed larger than the smaller file? Or when both files of different resolutions are viewed at the same size?
    – Michael C
    Jun 6 '16 at 7:01

No. The sensor is made of discrete photosites. When you reduce the resolution, the RAW data is still the same except that it is downsampled when rendered into a JPEG. So the pixels and amout of area of each photosite remains the same and is shot and read noise at each photosite.

Should you reduce the resolution you are also implicitly reducing the amount of dynamic-range in the image since a JPEG is 8-bit-per-component while a RAW file can have 12 or 14 bits, depending on the particular camera.

Yes. The apparent noise get reduced since if you are looking at 100% magnification, what you see is a smaller image with pixels binned together which averages out noise. Should you print at the same size though, the noise you see will be largely t he same though.

  • Thank you. It is very interesting, so if RAW file can be reduced to a lower resolution, then it will enlarge the pixel size? some cameras offer lower resolution in order to enlarge pixel size hence improve image quality?
    – xpw
    Jun 6 '16 at 5:35
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    No. They offer lower resolution to reduce the size of image files. There are many applications that can take the full size raw file and reduce the size of the image in a way that does a much better job at reducing noise than creating a smaller file in camera.
    – Michael C
    Jun 6 '16 at 6:57
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    A lot also depends on whether the camera in question uses the information from all of the sensor's pixels to create a smaller resolution image or whether the camera uses only part of the pixels (i.e. alternating groups of pixels) to produce the smaller image.
    – Michael C
    Jun 6 '16 at 6:59
  • There are also cameras that produce medium and small "raw" files from a larger sensor.
    – Michael C
    Jun 6 '16 at 7:22

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