What is Blue?

The color blue is an elusive one - it has a wide range, and interperatations of "blue" differs from person to person!

Hues Tracked

This site includes color swatches perceivable as "blue" - from the classic #0000FF blue to cyan, teal, turquoise, azure, and sometimes indigo.

A color is "blue" when its hue is between 170 - 250 degrees.

However, there are swatches on this site that go beyond the boundary. For example, documented swatches with "blue" in the name look arguably green; warmer blues (or indigo!) look blue but have a hue value of over 240.

Swatches outside the boundary have a rainbow icon.

Hue Breakdown

A swatch is organized into one of the three color categories - Cyan, Azure, and Blue.

Cyan is hue 180. The cyan range is 170 <= hue <= 195. Any swatch with hue value less than 170 is "beyond cyan".
Azure is hue 210. The azure range is 195 < hue <=225.
Blue is hue 240. The blue range is 225 < hue <= 250. Any swatch with hue value gresater than 250 is "beyond blue".

What is Indigo?

In my opinion, what we perceive as "blue" nowadays is indigo!

Colored pencils seem to agree with me on this one.

Shades of Gray

There are also different concentrations of "blue" - what makes a swatch grayish-blue versus a cool gray? Determining "gray" is impossible because it entirely relies on context, and everyone perceives color differently. Still, I have a way to categorize a swatch as a "gray," and while it's not perfect, it (hopefully) makes a more satisfying color gradient on the homepage.

Both spelling of "grey"/"gray" does appear in the documented swatches. I try to keep it as obtained, but do add the alternative spelling as alias.

A swatch is deemed "gray" and marked with a half-moon icon when it meets one of the following criteria:

Whiteness (W) and Blackness (B) from the HWB colorspace do not equal 0, AND
- Saturation (S) from the HSV colorspace is less than 50% AND sum of W and B is greater than 75, OR
- Sum of W and B is greater than or equal to 90, OR
- Sum of W and B is greater than 80, AND
  - Difference of W and B values is 0 ± 3, OR
  - S is less than or equal to 33.333%

Color Name Sources

Sources used for color swatches:

Crayola
Name that Color
Pantone
Sherwin Williams
Wikipedia
Winsor-Newton
XKCD - The blog post associated with this is a fun read.