Skip main navigation

Lossy compression

Besides lossless compression, the other type of data compression is lossy compression. Lossy compression algorithms reduce the number of bits necessary to store a file by removing unnecessary or less …

Lossless compression

As you learned in the previous step, compression reduces the amount of memory required to store a data file, but the output of a compressed data file can differ from …

Everyday compression

Digital images, videos, and articles are everywhere in our daily lives, and the speed at which they’re uploaded to social media or downloaded to your mobile phone continues to increase. …

Storing sound

As you learned earlier in the course, the size of files is important; generally, we want to keep media files as small as is possible while maintaining sufficient quality. The …

Sampling

As I described in the previous step, a computer records sound by converting an analogue electrical signal into a digital signal. This involves taking lots of individual measurements to approximate …

Analog and digital sound recordings

As you learned in the previous section, sound waves change air pressure. These changes are the basis for recording sound with analogue or digital methods. Both methods require a microphone …

The Physics of Sound

So you can understand how computers digitally represent sound, you first need to know a little about what sound is! Vibrations and waves Sound is all about vibration. To make …

Modifying images

Now that you know bitmap images are made up of tiny coloured pixels, in this and following steps you will dive into modifying these pixels and therefore, the pictures themselves …

File size calculation

Millions of images are being shared via social media in the time it takes you to read this sentence: the data in an image can be transferred within an instant. …

Emojis, Bitmap and Vector

You will now put what we discussed in the last step to use by creating some emoji. This will be a hands-on activity that you can use in the classroom …

Images as data

Welcome to Week 2 of Data Representation! Last week, you learned how computers represent data as text and colours. This week, we’re going to explore how digital images are encoded, …

Hexadecimal

Now you’ll learn the basics of the number system known as hexadecimal: I’ll give you an overview of the digits used to represent hexadecimal numbers, as well as how to …

RGB: red, green, and blue

When you look at your computer screen, you see a lot of different colours. However, this variety of colours is an illusion: computers essentially know only three different colours — …

Character encoding now

Two character encoding standards define how characters are decoded from ones and zeros into the text you see on the screen right now, and into the different languages viewed every …

The essentials of character encoding

From earlier sections in this course, you know that computers do not store digital media as letters, numbers, sounds, and pictures. Instead, computers work with bits, binary digits that have …