KLC Revision

• Computing
• Upper Secondary (Key Stage 4)
• Lower Secondary (Key Stage 3)

KLC Revision

8.2 KLC REVISION

Why is it important to have smaller file sizes?

How do we achieve this?

Lossy vs lossless

Lossy compression is a data compression method that deletes some information to achieve an even smaller file size than lossless compression. It is used on video, audio, and many types of image files.

In Audio there is data recorded at level humans cannot hear so these are removed, however in documents like Word there is no redundant data therefore they are lossless.

Image formats

Bitmaps - BMP. It is Lossless (no image data is lost on save) but there's also little to no compression at all, meaning saving as BMP results in VERY large file sizes.

JPG / JPEG - Joint Photographic Experts Group Jpeg format is used for color photographs, or any pictures with many blends or gradients.  it's a Lossy format, and saving the same file over and over will result in more data being lost over time.

GIF - Graphics Interchange Format. Gif format is best used for text, line drawings, screenshots, cartoons, and animations. Gif is limited to a total number of 256 colors or less. GIF uses lossless compression, meaning that you can save the image over and over and never lose any data. The file sizes are much smaller than BMP, because good compression is actually used, but it can only store an finite palette.

Smallest

Largest

Organise the objects by size from smallest to largest

Megabyte

Terabyte

Gigabyte

Kilobyte

Byte

How many bits are in a byte?

1. 1
2. 2
3. 4
4. 8

Images are made up of bits of data called pixels. Pixels are the smallest unit of a digital image. Each pixel is a small square that contains a colour.

The combination of pixels creates the whole image.

The number of pixels is called the resolution. The resolution of an image is calculated the same way as the area of a square:

width * height

12 * 19 = 

resolution of 

Color depth, also known as bit depth, refers to the number of bits used to represent the color of a single pixel in an image or on a display. 

What is the resolution of Mario?

1. 11
2. 12
3. 23
4. 132

What is the colour depth?

1. 4
2. 2
3. 12
4. 132

What colour is 11?

1. White
2. Red
3. Blue
4. Black

How do we get 91 ?

What is 11011101 in denary?

1. 201
2. 221
3. 255
4. 8

How do we solve this?

What does 1 + 1 = in binary

1. 0
2. 1
3. 2
4. 0 carry 1

1010 + 0001

1. 1011
2. 1111
3. 10110
4. 1001

How do we check 1010 + 0001?