Explained: What pixel binning means for smartphone photography

So what’s the massive deal? Why hasn’t pixel binning been extra widespread?

For many years, astrophotographers utilizing devoted astroimaging cameras have been capable of flip pixel binning on and off as a toggle of their digicam or software program settings.

So why haven’t shopper cameras supplied pixel binning till not too long ago?

The reply is that astroimaging cameras are historically monochrome cameras, and shopper cameras are coloration — and pixel binning turns into extra difficult with coloration cameras as a consequence of how they seize coloration knowledge.

Historically, astrophotographers would create a coloration picture by combining photos taken with a crimson filter, a inexperienced filter, and a blue filter. However since a filter wheel isn’t precisely a sensible accent for an on a regular basis digicam, most cameras seize coloration knowledge by embedding a sample of crimson, inexperienced, and blue coloration filters that covers each photosite (or pixel) on the picture sensor.

Put one other means, all coloration cameras are monochrome cameras — beneath their filter arrays.

Till not too long ago, almost each coloration digital digicam used alternating crimson/inexperienced and blue/inexperienced strains that kind a checkerboard-like sample known as a Bayer array. (A notable exception is Fujifilm’s in style X line of mirrorless cameras, which use an unconventional 6×6 sample.) The Bayer array is called for Bryce Bayer, who invented it whereas working for Kodak within the Nineteen Seventies.

In a Bayer array, each 2×2 group of pixels comprises two inexperienced pixels, located diagonally from one another, and one crimson and one blue pixel. To find out the colour at a selected level within the picture, the digicam’s inside processor samples surrounding pixels to interpolate full RGB coloration knowledge for every pixel in a course of known as demosaicing.

However a Bayer array makes pixel binning way more difficult. To take action, the digicam would usually sum the info from every crimson, inexperienced (2x), and blue grid into one worth — however that throws away the colour knowledge, leading to a monochrome picture. A extra difficult algorithm could be essential to bin every coloration individually, and this introduces artifacts and considerably negates the achieve in sensitivity.

To allow coloration cameras to pixel bin extra successfully, digicam sensor producers have rearranged your complete grid of filters right into a sample known as a quad-Bayer array (or quad-pixels, in Apple’s most popular terminology). On this sample, every 2×2 group is identical coloration, forming a bigger Bayer sample with 4 pixels in every superpixel.