Mixing Light Colours
Screens mix red, green and blue light. Paint mixes differently on paper. Know which world you are in.
- Explain additive RGB colour on screens
- Contrast screen light with paint or ink mixing
- Predict a colour from high red and low blue values
Finish first
Topic contents
Lesson 1 of 3
Light adds, paint subtracts
On a screen, pixels glow. Red plus green light makes yellow. Add blue too and you approach white. Turning all channels down goes toward black.
Paint on paper works the opposite way: you start with light paper and each pigment absorbs some colours. That is why art class and computer class use different words.
Open the pixel grid lab and raise only the red channel. Watch the square shift.
Pixel grid
Slide RGB values and watch one pixel change colour before scaling to a grid.
Pixel painter
Colours are three numbersRGB (255, 0, 0)
Red pixel
Pure red stores 255, 0, 0. Each number is one byte from 0 to 255.
Lesson 2 of 3
Reading triplets
255, 0, 0 is full red. 0, 255, 0 is full green. Equal high values make pale or white light.
Design tools show sliders for each channel. Games use the same numbers under the hood.
Watch the step-flow. See three channels slide and the square change.
Lesson 3 of 3
Resolution next
One pixel is one RGB triplet. Millions of pixels make a photo. Next topic counts how many dots fit on your screen.
When a projector looks muddy, check cable, bulb and resolution, not only RGB maths.
You now speak both art and computer colour a little, which helps when you edit slides or games.
Practice
Work these out yourself
No answer key here on purpose: these are the questions worth thinking through before you move on. Open one and work it out.
0/3 attemptedAssessment
Check your understanding
Answer each question, then read the explanation. That is where the learning is.
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