Digital signal and image processing
5 things
4 things every digital image is made of
4 things about digital images your lecturer assumes you know…
Quick check · tap an answer to continue
Lesson notes
Key points
- Pixels are samples: A digital image is a 2D grid of samples called pixels.
- 8 bits = 256 levels: An 8-bit greyscale pixel stores 256 intensity levels, from 0 black to 255 white.
- Colour = 3 channels: RGB images stack red, green and blue channels, so each pixel holds three values.
- Resolution vs quantisation: Spatial resolution counts pixels; quantisation counts intensity levels per pixel.
- Size = rows × cols × bits: Uncompressed size equals rows times columns times bits per pixel, times channels.
Takeaway: An image is a grid of quantised samples: pixels × bits.
Quick check: How many grey levels can one 8-bit greyscale pixel represent?
- 128
- 256
- 1024
8 bits give 2⁸ = 256 distinct levels, 0 to 255.
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