That Blue Square Thing

Computer Science GCSE

Note: this page deals with the old Edexcel GCSE (grades A-G) which no longer exists. I'm keeping it as an archive and because a number of the resources will still apply to newer (grades 1-9) courses. The AQA GCSE CompSci pages deal with a current course.

Data Encryption

Encryption plays a crucial part in allowing people to make effective use of computer networks.

Image Encoding

Just like anything, in order to be stored on a computer, images need to be encoded as numbers. The way this happens is important to understand.

In this section you need to be concerned about how Bitmap images work. Other image formats (such as JPEG) come into the section on data compression. The key things to understand in this section are:

Exam questions will focus on knowing the technical terms and how they work together to encode an image. You may well find that there are links to either data compression or file storage and transfer rates.

PDF iconImage representation - part 1 (detailed resource sheet)

PDF iconImage representation - part 2 of the above.

PDF iconBitmap image - a simple grid showing how a black and white bitmap is encoded using pixels

PDF iconResolution and Colour Depth - slides from class.

There is a section of the BBC Bitesize site with notes about image encodingwiki link, although not all of this is directly relevant to what you need to know. Focus on the points above - and the glossary at the bottom of the page is quite useful.