Unit 6 · Lesson 6
6 steps. Each one is a short story and a question to answer.
When you take a photo with your phone, the picture turns into numbers. How?
Digitization converts ordinary pictures into digital ones. The picture is split into tiny squares called pixels.
It has 3 stages: sampling (split into pixels and measure each one's brightness) then quantization (turn brightness into levels).
And finally encoding: express the values as binary 0s and 1s.
The smallest unit of a digital image is called a...
Pick an answer
Digitizing an image = sampling, then quantization, then encoding. Digitization converts ordinary pictures into digital ones. The picture is split into tiny squares called pixels. It has 3 stages: sampling (split into pixels and measure each one's brightness) then quantization (turn brightness into levels).
Higher resolution = more clarity + bigger file. Resolution is how fine the pixels are. It is measured in dpi (dots per inch) or in pixel count: vertical × horizontal. Like 600 × 800 or 1080 × 1920 pixels.
1 bit = black and white, 8 bits = 256 greys, 24 bits = 16 million colours. 1 bit = two colours (black and white): a binary image. 8 bits = 256 grey levels: a grayscale image. 24 bits per pixel = 16,777,216 colours: a full-colour image.
Size = vertical × horizontal pixels × colour bits, then ÷ 8 for bytes. First: number of pixels = 1280 × 720 = 921,600. Second: size in bits = 921,600 × 24 = 22,118,400 bits. Divide by 8 = 2,764,800 bytes.
RGB = light for screens. CMY = pigment for printers. RGB (red, green, blue): colours of light. Mixing them raises brightness: red + green + blue = white. Screens use it. CMY (cyan, magenta, yellow): colours of pigment. Mixing them darkens. Printers use it.
Bitmap = pixels and goes jagged. Vector = equations and stays sharp. A bitmap is a grid of pixels; enlarging shows jaggies. It suits photographs, like Photoshop. A vector image is points, lines and equations, staying sharp however much you enlarge. It suits logos, like Illustrator.
Scroll down ↓ to continue
Every idea in the lesson with its rule, ready to screenshot and revise from.
Digitizing an image = sampling, then quantization, then encoding
Higher resolution = more clarity + bigger file
1 bit = black and white, 8 bits = 256 greys, 24 bits = 16 million colours
Size = vertical × horizontal pixels × colour bits, then ÷ 8 for bytes
RGB = light for screens. CMY = pigment for printers
Bitmap = pixels and goes jagged. Vector = equations and stays sharp
One question from every step. Answer and see your score.
Question 1 of 6
The smallest unit of a digital image is called a...
Unit 6
Learn how an image turns into numbers: pixels, resolution and colour depth, RGB and CMY colours, how to calculate image size, and bitmap versus vector images, in an animated explainer.
The same explanation as the 3D scene, written out for quick review.
Digitizing an image = sampling, then quantization, then encoding. Digitization converts ordinary pictures into digital ones. The picture is split into tiny squares called pixels. It has 3 stages: sampling (split into pixels and measure each one's brightness) then quantization (turn brightness into levels).
Page 130, 131
Higher resolution = more clarity + bigger file. Resolution is how fine the pixels are. It is measured in dpi (dots per inch) or in pixel count: vertical × horizontal. Like 600 × 800 or 1080 × 1920 pixels.
Page 131
1 bit = black and white, 8 bits = 256 greys, 24 bits = 16 million colours. 1 bit = two colours (black and white): a binary image. 8 bits = 256 grey levels: a grayscale image. 24 bits per pixel = 16,777,216 colours: a full-colour image.
Page 131, 132
Size = vertical × horizontal pixels × colour bits, then ÷ 8 for bytes. First: number of pixels = 1280 × 720 = 921,600. Second: size in bits = 921,600 × 24 = 22,118,400 bits. Divide by 8 = 2,764,800 bytes.
Page 132, 135
RGB = light for screens. CMY = pigment for printers. RGB (red, green, blue): colours of light. Mixing them raises brightness: red + green + blue = white. Screens use it. CMY (cyan, magenta, yellow): colours of pigment. Mixing them darkens. Printers use it.
Page 133, 134
Bitmap = pixels and goes jagged. Vector = equations and stays sharp. A bitmap is a grid of pixels; enlarging shows jaggies. It suits photographs, like Photoshop. A vector image is points, lines and equations, staying sharp however much you enlarge. It suits logos, like Illustrator.
Page 133, 139