Helmlab Metric

The Helmlab Metric color space is not registered in Color by default

Properties

Name: helmlab-metric

White Point: D65 / 2˚ (Variant from ASTM-E308)

Coordinates:

Name	Range^*
`l`	[0, ~1.6]
`a`	[-1.5, 1.5]
`b`	[-1.5, 1.5]

^* Space is not bound to the range and is only used as a reference to define percentage inputs/outputs.

Helmlab is a family of purpose-built color spaces, two to be exact. The first is the Helmlab Metric space which is designed for perceptual distance measurements, claiming STRESS 23.30 on COMBVD - 20% better than CIEDE2000. The second is the Helmgen space which is designed for gradient and palette generation (60-8 vs Oklab on ColorBench's 83 metrics, 360/360/360 gamut cusps, zero monotonicity violations).

Helmlab Metric is the metric space and is specifically used for color distancing and is not meant to be used for interpolation and palettes, and least not directly.

Learn more.

Channel Aliases

Channels	Aliases
`l`	`lightness`
`a`
`b`

Inputs

The Helmlab Metric space is not currently supported in the CSS spec, the parsed input and string output formats use the color() function format using the custom name --helmlab-metric:

color(--helmlab-metric l a b / a)  // Color function

The string representation of the color object and the default string output use the color(--helmlab-metric l a b / a) form.

>>> Color("helmlab-metric", [0.9207, 0.94084, -0.2063])
color(--helmlab-metric 0.9207 0.94084 -0.2063 / 1)
>>> Color("helmlab-metric", [1.0056, 0.80476, 0.71403]).to_string()
'color(--helmlab-metric 1.0056 0.80476 0.71403)'

Registering

from coloraide import Color as Base
from coloraide.spaces.helmlab_metric import HelmlabMetric

class Color(Base): ...

Color.register(HelmlabMetric())