The RGB colour model is an additive model in which the red, green, and blue primary colors of light are added together to reproduce a broad spectrum of colours. In the case of thistle, using 8-bit 0–255 values for each channel, it is red 217, green 191, blue 217.
The CIELAB color space expresses color as three values: L* for perceptual lightness, and a* and b* for the colours of human vision: red-green, blue-yellow.
Thistle is a light purple resembling the flower of the thistle plant.
In terms of colour temperature, thistle is considered a cool colour.