Spectral Colour and the RGB Colour Model
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Description
Spectral Colour and the RGB Colour Model
Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!
- What are spectral colours?
- What wavelengths correspond with the extreme limits of the visible spectrum?
- Does each wavelength of visible light correspond with a unique spectral colour?
- Are rainbow colours spectral colours?
- Are colours produced by combining RGB primary colours spectral colours?
About the Diagram
Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!
This diagram shows six spectral colours – red, orange, yellow, green, blue and violet.
- Spectral colours are produced by a single wavelength of light.
- Some spectral colours can also be produced by mixing two wavelengths of light together.
Understanding the diagram:
- Above the line of coloured circles are the wavelengths of light that produce each spectral colour.
- Of the six colours (ROYGBV), red, green and blue can only be produced by a single wavelength of light.
- The other three spectral colours, orange, yellow and violet, can be produced either by a single wavelength of light or by additive mixing of pairs of primary colours.
- The bottom line of colours shows the proportions of red, green or blue used to produce orange, yellow and violet.
- The wavelength corresponding with each colour is shown in nanometres (nm). The wavelengths shown for each colour are for illustration only.
- In practice, the choice of wavelengths for primary colours usually depends on factors such as the colour model being used, the gamut of colours that a display device can produce and the context in which colours are to be viewed.
Remember that:
- The bands of colour we see in rainbows correspond with the spectral colours red, orange, yellow, green, blue and violet.
- Spectral colours are produced naturally when light is refracted and dispersed by a prism or by rain.
- A spectral colour is produced by a single wavelength of light.
- The visible spectrum contains a continuum of spectral colours between red and violet.
- The visible spectrum is a small part of the electromagnetic spectrum.
- In a continuous spectrum, separate colours may be indistinguishable to the human eye.
- The fact that we see distinct bands of colour in a rainbow is an artefact of human colour vision.
Spectral and RGB colours
- Spectral colour should not be confused with RGB colour.
- Spectral colours are components of the visible spectrum.
- RGB colours are produced by mixing wavelengths of light corresponding with the three additive primary colours – red, green and blue.
- A diagram of spectral colour is usually presented in the form of a continuous linear spectrum organised by wavelength, so with red at one end and violet at the other.
- A diagram of RGB colour is often represented in the form of a colour wheel and shows the colours produced by mixing adjacent colours on the wheel.
Follow the blue links for definitions . . . . or check the summaries of key terms below!
Some Key Terms
Move to the next level! Check out the following terms.
Primary colour
Read More
RGB colour
Read More
Secondary colour
Read More
Colour model
Read More
Spectral colour
Read More
Visible spectrum
Read More
More Information
ABOUT SLIDES
Slides
All images on the lightcolourvision.org website are available for download as either slides or diagrams.
All slides share common specifications:
- Titles: All slides have titles.
- Backgrounds: Black, framed with a violet gradient.
- Size: 1686 x 1124 pixels (3:2 aspect ratio).
- Slides are available in two file formats: JPG, AI (Adobe Illustrator).
Slides are optimized for viewing on-screen or with a projector.
Diagrams are optimized for printing on A4 pages in portrait format.
ABOUT DIAGRAMS
Diagrams
All images on the lightcolourvision.org website are available for download as either slides or diagrams.
All diagrams share common specifications:
- Titles: No titles.
- Backgrounds: White.
- Size: 1686 pixels wide. So all diagrams reproduce at the same scale when inserted into Word documents etc.
- Labels: Calibri 24pt Italic.
- Diagrams are available in two file formats: JPG, AI (Adobe Illustrator).
Diagrams are optimized for printing on A4 pages in portrait format.
Slides are optimized for viewing on-screen or using a projector.
FILE TYPES - JPG
JPG file format
Download the image at the top of this page as a JPG file:
- All JPG images available for download are 1686px wide.
- Text on JPG images with white backgrounds is styled as Calibri 24pt Italic.
- If the image you need is not exactly right, download it as an AI (Adobe Illustrator) file and edit it.
- All the images on these Resource Pages were created in Adobe Illustrator and are vector drawings.
Did you know:
- JPG stands for Joint Photographic Experts Group who created the standard.
- The JPG file extension is used interchangeably with JPEG.
- JPG files can be compressed for use on websites.
- JPG files can be placed or pasted directly into MS Office documents.
FILE TYPES - AI
AI (Adobe Illustrator) file format
Download the image at the top of this page as an AI (Adobe Illustrator) file:
- All AI images available for download from lightcolourvision.org are 1686px wide.
- All the images on these Resource Pages were created in Adobe Illustrator and are vector drawings.
- Vector drawing can be scaled up or down without any loss of quality.
Did you know:
- AI files downloaded from lightcolourvision.org can be re-edited using Adobe Illustrator for your own personal use.
- Adobe Illustrator can save or export AI files to other formats including PDF (.pdf), PNG (.png), JPG (.jpeg) and SVG(.svg) etc.
DOWNLOAD AGREEMENT
Download agreement
Download Agreement
Before downloading or cutting and pasting from lightcolourvision.org we ask you to agree to the following terms:
- All information, images and other assets displayed or made available for download on the lightcolourvision.org website are copyright. This means there are limitations on how they can be used.
- All information, images and other assets displayed or made available for download are solely and exclusively to be used for personal, educational and non-profit purposes.
- When you find the resources you need, then part of the download process involves you (the user) ticking a box to let us (at lightcolourvision.org) know we both agree how the material can be used.
- Please contact [email protected] before considering any use not covered by the terms of the agreement above.
If you are a student, educator or researcher you might also like to read our posts Copyright: Credit where credit’s due and Citation and bibliographies before copying and pasting material into essays, assignments or other academic work. They include advice on avoiding plagiarism and how to credit other people’s words, images and assets before submitting your work for marking or assessment. If you are confused, just ask a friendly teacher, librarian, or other member of academic staff.
Like to know more?
Please contact [email protected] if you have questions about any aspect of this project.
