oklab

README

An Oklab color space for Go.
Oklch is the same color space with polar coordinates.

See https://bottosson.github.io/posts/oklab/

Documentation

Overview

Package oklab implements the Oklab color space, as described at https://bottosson.github.io/posts/oklab/

Example (ConvertOklabToRGB)

package main

import (
	"fmt"
	"github.com/alltom/oklab"
)

func main() {
	oklabc := oklab.Oklab{L: 0.9322421414586456, A: 0.03673270292094283, B: 0.0006123556644819055}
	r, g, b, _ := oklabc.RGBA()
	fmt.Printf("R: 0x%x, G: 0x%x, B: 0x%x\n", r>>8, g>>8, b>>8)
}

Output:

R: 0xff, G: 0xdf, B: 0xe7

Example (ConvertToOklab)

package main

import (
	"fmt"
	"github.com/alltom/oklab"
	"image/color"
)

func main() {
	rgbc := color.RGBA{0xff, 0xdf, 0xe7, 0xff}
	oklabc := oklab.OklabModel.Convert(rgbc).(oklab.Oklab)
	fmt.Printf("L: %.2f, a: %.2f, b: %.2f\n", oklabc.L, oklabc.A, oklabc.B)
}

Output:

L: 0.93, a: 0.04, b: 0.00

Example (GradientImage)

package main

import (
	"fmt"
	"github.com/alltom/oklab"
	"image"
	"image/color"
	"image/png"
	"os"
)

func main() {
	f, _ := os.Create("gradient.png")
	png.Encode(f, GradientImage{})
	fmt.Println("err =", f.Close())
}

type GradientImage struct{}

func (g GradientImage) ColorModel() color.Model {
	return oklab.OklabModel
}

func (g GradientImage) Bounds() image.Rectangle {
	return image.Rect(0, 0, 1200, 600)
}

func (g GradientImage) At(x, y int) color.Color {
	a := lerp(float64(x)/float64(g.Bounds().Dx()), -0.233888, 0.276216)
	b := lerp(float64(y)/float64(g.Bounds().Dy()), -0.311528, 0.198570)
	return oklab.Oklab{0.8, a, b}
}

func lerp(x, min, max float64) float64 {
	return x*(max-min) + min
}

Output:

err = <nil>

Index

• Variables
• type Oklab
  • func (c Oklab) LinearSRGB() (float64, float64, float64)
  • func (c Oklab) Oklch() Oklch
  • func (c Oklab) RGBA() (uint32, uint32, uint32, uint32)
  • func (c Oklab) SRGB() (float64, float64, float64)
• type Oklch
  • func (c Oklch) Oklab() Oklab
  • func (c Oklch) RGBA() (uint32, uint32, uint32, uint32)

Examples

• Package (ConvertOklabToRGB)
• Package (ConvertToOklab)
• Package (GradientImage)

Variables

var OklabModel = color.ModelFunc(oklabModel)

var OklchModel = color.ModelFunc(oklchModel)

Types

type Oklab

type Oklab struct {
	L float64 // Perceived lightness
	A float64 // How green/red the color is
	B float64 // How blue/yellow the color is
}

func (Oklab) LinearSRGB

func (c Oklab) LinearSRGB() (float64, float64, float64)

Convert to linear sRGB. See https://bottosson.github.io/posts/oklab/

func (Oklab) Oklch

func (c Oklab) Oklch() Oklch

Convert to LCh, which is Oklab in polar.

func (Oklab) RGBA

func (c Oklab) RGBA() (uint32, uint32, uint32, uint32)

See image.Color.

func (Oklab) SRGB

func (c Oklab) SRGB() (float64, float64, float64)

Convert to sRGB. See https://bottosson.github.io/posts/colorwrong/#what-can-we-do%3F

type Oklch

type Oklch struct {
	L float64 // Perceived lightness
	C float64 // Chroma
	H float64 // Hue
}

func (Oklch) Oklab

func (c Oklch) Oklab() Oklab

Convert to Oklab.

func (Oklch) RGBA

func (c Oklch) RGBA() (uint32, uint32, uint32, uint32)

See image.Color.