Pixels and Perception

Sharpness has become a mainstream aesthetic. It's not unusual to hear rhetorics such as "it's between a sharp image and a missed opportunity."

But what do we really mean by sharp?

There is sharpness at the focus point, which requires understanding of the mechanisms of photography. Think the exposure triangle on the textbook.

Then there is sharpness by perception. Think retina display.

Below is an investigation on the latter, focused on the digital (both in production and in dissemination).

I am writing it out simply because I sense a data inflation among all the screens that surround us, and I'd like to do some calculations to prove my hypothesis.

Image as Data

In the broadest strokes and from my current understanding, three things affect digital sharpness:

the photosensor determines the capacity of maximum data input
the image quality (a setting on the camera) regulates the actual data stored
the display/physical medium that outputs the image (to be perceived by a human)

A digital Input to a digital Output interests me the most because of its potential to show how the sharpness we think we are seeing is not what we actually see. What we actually see is probably simpler... We might be able to rethink about sharpness and whether it matters at all.

Photosensor

This actual size of the 5D Mark III sensor is 36mm x 24 mm, which translates to this:

surface area	864 mm²
photosites (pixels)	22,300,000
pixel pitch	6.22 µm
photosite (pixel) area = pixel pitch²	38.69 µm²
pixel density[1]	2.58 MP/cm²

Pixel pitch tells you the distance from the center of one photosite(pixel) to the center of the next. The larger the photosite, the more light it can capture and the more information can be recorded. Pixel density tells you how many million pixels fit or would fit in one square cm of the sensor.[2]

Image Quality

something

Display