Digital Image Processing Fundamentals

3 min readApr 1, 2023

an introduction

What is Digital Image Processing

Digital images are pictures that have been converted into a computer readable format (binary).
From this we can also think of an image like a two-dimensional function, f(x,y), where x and y are spatial coordinates, and the amplitude of f at any pair of coordinates (x,y) is the intensity or gray level of the image at that point.
With this we can, not surprisingly, say that the field of digital image processing refers to processing digital images by means of a digital computer.
Like almost everything in nature, with the exception of the universe perhaps, images are composed of finite elements. These elements have different names but the most popular is pixels (More on these definitions in chapter 2).

The simplest way to put it is to understand that digital image processing handles images and videos at the pixel level. Computer vision does not go that deep, it mostly handles image recognition for applications like self- driving cars or a camera that can identify a fire to put it out.

In the 1920 s a technique was invented to transmit digitized newspaper images over submarine cable lines between London and New York.
This technique was called the Bartlane Transmission System and it was created by Harry G. Bartholomew and Maynard D. McFarlane.
To create images this system used a telegraphic typewriter coded in a 5 level Gray code.
In 1929 the coding level was increased to 15

The applications are really very wide and can go from x-ray images to analyzing deep ground images for petroleum extraction.

Gamma-Ray Imaging

Used for nuclear medicine and astronomical observations
In nuclear medicine the idea is to inject a patient with a radioactive isotope that emits gamma rays as it decays. Then images are produced from these emissions by.

X-Ray Imaging

Among the oldest sources of EM radiation used for imaging.
Usually it is used for medical diagnostics, however it is also used in astronomy. X-Ray machines work with an
X-Ray tube, which is a vacuum tube with a cathode and anode. When the cathode is heated, it releases electrons at a high speed. Then these electrons flow to the positively charged anode. When an electron strikes a nucleus, energy is released in the form of X-Ray radiation.
The penetrating power of X-rays is modulated by applying a voltage across the anode, and by a current applied to the filament in the cathode.

Imaging in the Ultraviolet Band

Applications here vary from lithography, industrial inspection, microscopy, lasers, biological imaging, and astronomical observations.
Ultraviolet light itself is not visible, but when a photon of light collides with an electron in an atom of a fluorescent material, it elevates the electron to a higher energy level. Subsequently, the electron goes back to a lower energy level and emits light in the form of a lower-energy photon in the visible (red) light region,

Imaging in the visible and infrared band

Like in the previous applications, the uses vary from medical uses to industrial uses.
Thematic bands of NASAs LANDSAT satellite.