It has been quite long in this situation of COVID-19 lockdown. This gave me a good opportunity to dive deep into the world of unknowns. We as designers come across a lot of terms in our daily lives but never understood why they are called so.

Raster Images - How did this term come into existence?

One such term is ‘raster’. Every day, we use thousands of files which are raster graphics. Commonly accepted, a raster graphic is a picture composed of pixels or dots. But in its essence, it is connected with lines rather the dots or pixels.

(Source - https://www.hisour.com/rastrum-18522/)

Long before the televisions or CRT monitors were able to create graphics using cathode rays, the musicians used a special type of pen, called ‘rastrum’ or ‘raster’ to create ruled lines for music sheets. The shape of these pens closely resembled a rake, which is used to clean dry leaves.

The history

Interestingly enough, the word raster in its roots is also derived from the Latin word ‘rastrum’ which literally means ‘rake’.

The process began to be called ‘rasterization’ when the pictures were broken into lines to be displayed using pinholes, in the early 1900s. This later gave the idea a direction to be developed into a video camera as well.

Technicality

Presently, a raster graphic is produced or seen, when cathode ray scans line by line data and displays it on the screen. These lines in combination form a screen composed of pixels or dots, thus giving the word ‘raster’ its present meaning of a graphic composed of pixels and dots.