It's often easy to see contrast between colours, but it's not always obvious which colour is lighter or darker. The Value Slider takes the guesswork out of Value by taking the colour out of colour . . .
THE VALUE OF VALUE
Exploring the 3 main properties of colour, the Hue Matrix shows us a colour's 'colour,' distilled down to its element primary ingredients. The Saturation Summary shows us how those ingredients add up to reflect a colour's purity, from full Hue to completely hueless. The third infographic on the Code Side of every BTC Colour Card is the Value Slider.
Using a scale of 0 to 100 (0 being none and 100 being 100%), the Value Slider shows how light or dark a colour is, independent of its Hue. An exact Grey version of the Hue is shown in its approximate position on the Value Slider between Black (on the left) and White (on the right). Values are rounded off to whole numbers. Regardless of where the hueless Hue is on this horizontal Grey scale, the two numbers will always add up to 100.
Colours that have a high ratio of White are easy to perceive as 'light' colours, and their hueless versions will be lighter greys. Colours that contain a lot of Black obviously read as 'dark' colours, and their hueless versions will be darker greys.
But all colours have a place on the range between light and dark, even if they don't contain any White or Black at all. Here are all the Corner Colours and their Value Slider values, from lightest to darkest between pure White and full Black:
Here are all 8 Corners from lightest (White) to darkest (Black), in both their full colour and hueless versions:
SHADES LIGHTER THAN TINTS
A colour that contains White is by definition a Tint, but just because a colour has White in it doesn't mean it will be 'lighter' than a colour that doesn't. And colours with Black, while they are by definition Shades, aren't necessarily going to be darker than every colour that has no added Black at all. This is because pure Hues have different Values to begin with, and some are much lighter or darker than others. For example, pure Yellow is much lighter than pure Blue, so even Yellow with Black is lighter than Blue with White:
DIFFERENT HUES, SAME VALUES
It's not always easy to see the lightness or darkness of Value in a Hue, especially if (or even if) it isn't an obvious Tint or Shade. The Value Slider gives us a definitive reference, making it easy to put colours in 'order.' It also shows us that just because colours may be obviously different in Hue, they may not be that different in Value. For example, we know from the Corner Colours above that Cyan has a Value of 30 Black and 70 White. Here's Cyan with some other colours that are obviously not Cyan, but when you see them all in 'black and white,' you can see they have the same basic Value:
It's easy to see contrast in Hue, but it's also important to understand and be aware of contrast in Value. Sometimes all that colour actually makes it hard to see the value of Value, but the Value Slider takes colour out of the equation and gives every Hue, Tint, Shade, and Tone an exact place in the achromatic ranks.