Smoothing and Sharpening
This picture, like any other digital picture is made up of individual coloured squares called pixels.
A standard HD screen has 1920 pixels horizontally and 1080 vertically. The colour in that pixel is produced by mixing red, green and blue light. The information of the intensity of each colour is contained in 1 byte of information
A byte consists of 8 bits, each one of which can be coded to 0 or 1. The total number of levels of intensity is therefore 2 to the power 8 or 256. So, in total each pixel is defined by 3 numbers each with a range of 256, that is a potential total of 256 x 256 x 256 colours
Digital images can be improved, or altered for a special purpose, by many processes including by smoothing or sharpening which seems contradictory.
Smoothing
Within any picture a few of the pixels will be“wrong”. There will be errors in the recording. For example this blue pixel is darker than the others around it. We can reduce these by smoothing.
The software examines the code of each pixel and makes each an average of those immediately around, like this (the numbers are kept small here to make the example easier to follow):
Smoothing reduces these odd errors but will also remove other information from the image. Note that the edge between the blue and the head is softened and blurred.
Sharpening does the opposite to smoothing, enhancing the differences between adjacent pixels and increasing the contrast at boundaries between colours. The arithmetic works like this:
