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Care for a Byte – Explaining Bits, Bytes and More

bits-bytes.pngWhat is it with these bytes? And what about the bits? Are you up with the bits and bytes?

It’s estimated that, each year more than 80 billion plus photographs are taken worldwide; if they were all digital you’d need more than 400 Petabytes (PB) of storage.

A Petabyte is about half the content of all the US’s academic libraries. Up with your bits and bytes?


A bit is a binary digit — the basic unit of information storage. The bit is also a unit of measurement, the information capacity of one binary digit. A single bit is a one or a zero.

A byte (abbreviation: B) mostly consists of eight bits; a Kilobyte (KB) is 1024 bytes; a Megabyte (MB) is 1024 Kilobytes; a Gigabyte (GB) is 1024 Megabytes; a Terabyte (TB) is 1024 Gigabytes; a Petabyte (PB) is 1024 Terabytes; an Exabyte (EB) is 1024 Petabytes; a Zettabyte (ZB) is 1024 Exabytes; a Yottabyte (YB) is 1024 Zettabytes.

Five Exabytes equates to all the words ever spoken; a Zettabyte is the number of all the grains of sand on every beach in the world. A Yottabyte equals the number of atoms in 7000 human bodies.

If you have trouble remembering all that that, just recite Baudy Kings Must Gallop Towards Petulant Elephants Zoo-bound Yearly.
Got it?

Bit Depth
Life was easy when digital images were described as having a bit depth of 8-bits. These days it’s not unusual to see cameras that will capture images in 12-bit and 16-bits.

The more bits, the more gradation information an image can hold.

A 2-bit image is a limited grey scale image and contains four grey tones.

A 2-bit image

A 2-bit image

A 4-bit Image

A 4-bit Image

An 8-bit image can hold 256 levels of grey in a monochrome image. An 8-bit, three colour image (red, green and blue) can also be described as a 24-bit image … 8-bits for each of the three colours. This means an 8-bit image can contain over 16 million possible colours.

An 8-bit Image

An 8-bit Image

A three colour, 16-bit image can contain almost three billion colours.

However, in the real world we can only really see about 7-8 million discrete colours and print out, at most, a few tens of thousands of colours on the best of output devices.

A massive colour range allows us increased editing elbow room.


Hard Drive.jpg
Have you ever wondered why your 80GB drive cannot hold 80GB of data? The answer is that the magnetic surface of the hard drive is divided into sectors; this formatting soaks up capacity so that the 80GB becomes a 75GB.

In similar fashion a 2GB flash memory stick will allow the storage of only 1.8GB of data.

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Barrie Smith

Barrie Smith is an experienced writer/photographer currently published in Australian Macworld, Auscam and other magazines in Australia and overseas.

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