Images
Pixels, resolution, colour depth, image file size and metadata.
Transcript
An image is a grid of tiny squares called pixels. Each pixel is stored as a binary number that says which colour it is.
The number of pixels is the resolution, written as width by height. More pixels means more detail, but a bigger file.
Colour depth is the number of bits used for each pixel. One bit gives two colours. Two bits give four. Eight bits give two hundred and fifty six.
To work out the file size, multiply the width, the height and the colour depth. One hundred by fifty pixels at eight bits is forty thousand bits, or five thousand bytes.
The file also stores metadata, such as the width, the height and the colour depth. Without it, the computer could not rebuild the picture.
Pixels make the picture, resolution sets the detail, and colour depth sets the colours. More of either means a bigger file.
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2:30Binary addition, overflow and shifts
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2:12Two's complement
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1:45Text: ASCII and Unicode
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1:38Sound
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1:50Storage units and file sizes
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1:58Compression
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5:38Unit 1 quiz
Ten questions with a think-time countdown and explained answers.