Before knowing about pixel binning, it is important to get a clear binning concept in a mobile camera. Simply the smallest unit of the digital image is a pixel. It can display only on digital display devices. The term pixel is combined of picture elements (pix= picture and el= element). Pixels are created using geometric coordinates which are the basic block building of digital imaging.
Pixels are varied due to quantity, size, and color combination depending on the graphics card and displaying monitor. It measures by display resolutions. For example, display resolution with 1080×720 will make a maximum of 777600 pixels on the showing screen. Pixel is square-shaped which means sampling pitches are equal both vertically and horizontally.
Pixel Binning:
It is the latest technology in the camera segment (especially for a smartphone camera). It designs for making image sensors sustainable to different conditions. According to Hamamatsu, pixel binning is a clocking scheme used to combine the charge collected by several adjacent CCD pixels.
The designation is to reduce noise and improve the signal-to-noise ratio and frame rate in digital cameras. It performs by on-chip CCD clock timing circuitry. It assumes control of the serial and parallel shift registers prior to amplification of the CCD analog signal.
To better understand pixel binning, you have to know about the image sensor of a digital camera. It is a silicon chip containing millions of pixels of the grid that capture the light that comes through the lens.
What is the purpose of Pixel Binning?
The main reason for pixels binning is to increase the signal-to-noise ratio (SNR). It is a key metric in analog applications in the case of image sensing. It is particularly very useful to get brightness in extremely low light conditions. Point for the note, some sensors make average performance (binning) instead of additive binning.
To get a better signal-to-noise ratio, both techniques lead to making the ultimate goal. Sometimes, it is not clear always depending on the context. But the question might be arisen, from where does the noise come? Pixel binning more precisely helps to reduce noise, most possibly from 3 main sources, noise comes out.
Firstly, shot noises due to light captured by the sensor and converted to electron charges. Secondly, read noise when we read the data from the sensor while converting analog to digital. Lastly, thermal noise when electron released by the sensor itself.
Disadvantages:
One of the biggest negative issues of pixel binning is to divide the resolution by four when you take a pixel binned shot. More precisely a binned shot on a 64MP camera is actually taken by 16MP. Pixel binning can not remove the dark current noise. It overcame by cooling the CCD to low temperature.
For the same size sensor of 16 megapixels, the real 16 megapixels would perform better than a binned 16 megapixels. When shooting at full resolution, need more image processing which can lead to draining your phone’s battery.