Physics/Optics/Principles and Exploration
Light and color mixing — principles and investigation
Mixing light on the screen and overlapping color filters have different results. Compare the additive mixture of red, green, and blue with the anomalous filter mixture of cyan, magenta, and yellow. Changes in color can be explained by thinking about what light is added or prevented from passing through the overlapping areas.
How does it work?
R+G is yellow, C+M is blue. Three lights are white, and three or more filters are black.
RGB: Add light CMY: Absorb light
Try this investigation
- Drag the circles or press the Overlap/Separate All button to look at the overlapped areas. Measure the color of the center cross.
- In RGB mode, two and three lights are overlapped and recorded. After execution, record the value of the center point.
- Change to CMY subtraction to record C+M, three colors, and only change the intensity of one light in RGB.
Interpreting your results
In CMY mode, what is the area where cyan and magenta overlap the most?
Cyan absorbs red, and magenta absorbs green, leaving only blue.
Assumptions and limitations
RGB combines linear light amounts and converts them to sRGB. CMY is a simple subtractive approximation that uses the abnormal transmittance (1−C, 1−M, 1−Y) for each channel. It does not reproduce the scattering, spectral absorption, paper, or printing characteristics of actual paints. Screen px are coordinates for placement, not physical length.