vibrant

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README

Vibrant

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Vibrant is a customizable Go library for extracting colors from images. It is largely based on Android's Palette class.

Example usages can be found in the documentation and in the cli directory`.

Author

Rob Cherry

Special Thanks

Documentation

Index

Examples

Constants

View Source 
const (
	DefaultFilterMinLightness = 0.05
	DefaultFilterMaxLightness = 0.95
)

Default values for the default filter.

View Source 
const (
	DefaultResizeArea        = uint64(320 * 320)
	DefaultMaximumColorCount = uint32(64)
)

Defaults used by the default PaletteBuilder.

View Source 
const (
	MinNormalLightness    = 0.3
	TargetNormalLightness = 0.5
	MaxNormalLightness    = 0.7

	MinLightLightness    = 0.55
	TargetLightLightness = 0.74

	TargetDarkLightness = 0.26
	MaxDarkLightness    = 0.45

	TargetVibrantSaturation = 1
	MinVibrantSaturation    = 0.35

	TargetMutedSaturation = 0.3
	MaxMutedSaturation    = 0.4

	// Weights used by the default scoring function.
	DefaultSaturationWeight = 0.375
	DefaultLightnessWeight  = 0.575
	DefaultPopulationWeight = 0.05
)

Constants used by the default targets.

Variables

View Source 
var DefaultFilter = NewLightnessFilter(DefaultFilterMinLightness, DefaultFilterMaxLightness)

DefaultFilter removes colors close to white and black.

View Source 
var (
	DefaultScaler = draw.ApproxBiLinear
)

Defaults used by the default PaletteBuilder.

View Source 
var HSLModel = color.ModelFunc(func(c color.Color) color.Color {
	if _, ok := c.(HSL); ok {
		return c
	}
	nrgba := color.NRGBAModel.Convert(c).(color.NRGBA)
	h, s, l := rgbToHSL(nrgba.R, nrgba.G, nrgba.B)
	return HSL{h, s, l, nrgba.A}
})

HSLModel is the color.Model for the HSL type.

View Source 
var QuantizedColorGenerator = func(r, g, b uint8) QuantizedColor {
	quantizedRed := quantizeColorValue(r)
	quantizedGreen := quantizeColorValue(g)
	quantizedBlue := quantizeColorValue(b)
	return QuantizedColor((quantizedRed << (quantizeWordWidth + quantizeWordWidth)) | (quantizedGreen << quantizeWordWidth) | quantizedBlue)
}

QuantizedColorGenerator creates a new QuantizedColor from a given red, green, and blue value.

View Source 
var QuantizedColorModel = color.ModelFunc(func(c color.Color) color.Color {
	if _, ok := c.(QuantizedColor); ok {
		return c
	}
	nrgba := color.NRGBAModel.Convert(c).(color.NRGBA)
	return QuantizedColorGenerator(nrgba.R, nrgba.G, nrgba.B)
})

QuantizedColorModel is the color.Model for the QuantizedColor type.

View Source 
var RGBAIntModel = color.ModelFunc(func(c color.Color) color.Color {
	if _, ok := c.(RGBAInt); ok {
		return c
	}
	nrgba := color.NRGBAModel.Convert(c).(color.NRGBA)
	return RGBAInt((uint32(nrgba.A) << 24) | (uint32(nrgba.R) << 16) | (uint32(nrgba.G) << 8) | uint32(nrgba.B))
})

RGBAIntModel is the color.Model for the RGBAInt type.

Functions

func ScaleImageDown 

func ScaleImageDown(src image.Image, resizeArea uint64, scaler draw.Scaler) image.Image

ScaleImageDown will scale the image down as needed. This is relatively slow.

Types

type ColorCutQuantizer 

type ColorCutQuantizer struct {
	// contains filtered or unexported fields
}

ColorCutQuantizer is a color quantizer based on the Median-cut algorithm, but optimized for picking out distinct colors rather than representation colors.

The color space is represented as a 3-dimensional cube with each dimension being an RGB component. The cube is then repeatedly divided until we have reduced the color space to the requested number of colors. An average color is then generated from each cube.

What makes this different to median-cut is that median-cut divided cubes so that all of the cubes have roughly the same population, where this quantizer divides boxes based on their color volume. This means that the color space is divided into distinct colors, rather than representative colors.

func NewColorCutQuantizer 

func NewColorCutQuantizer() *ColorCutQuantizer

NewColorCutQuantizer creates a default ColorCutQuantizer.

func NewColorCutQuantizerWithFilters 

func NewColorCutQuantizerWithFilters(filters []Filter) *ColorCutQuantizer

NewColorCutQuantizerWithFilters creates a ColorCutQuantizer with custom filters.

func (*ColorCutQuantizer) Quantize 

func (q *ColorCutQuantizer) Quantize(p color.Palette, m image.Image) color.Palette

Quantize populates a color palette for the image.

func (*ColorCutQuantizer) Swatches 

func (q *ColorCutQuantizer) Swatches(colorCount uint32, m image.Image) []*Swatch

Swatches returns a slice of swaches generated from the image.

type DefaultScorer 

type DefaultScorer struct {
	// contains filtered or unexported fields
}

DefaultScorer is the default scorer implementation used to score a Target.

func (DefaultScorer) Score 

func (s DefaultScorer) Score(swatch *Swatch) float64

Score returns the score for a Swatch.

type Filter 

type Filter interface {
	// contains filtered or unexported methods
}

A Filter provides a mechanism for exercising fine-grained control over which colors are valid within a resulting Palette.

func NewLightnessFilter 

func NewLightnessFilter(blackMaxLightness float64, whiteMinimumLightness float64) Filter

NewLightnessFilter creates a Filter that removes colors based on a lightness.

type HSL 

type HSL struct {
	H, S, L float64
	A       uint8
}

HSL represents the HSL value for an RGBA color.

func (HSL) RGBA 

func (c HSL) RGBA() (uint32, uint32, uint32, uint32)

RGBA implements the color.Color interface.

func (HSL) String 

func (c HSL) String() string

type Palette 

type Palette struct {
	// contains filtered or unexported fields
}

Palette extracts prominent colors from an image.

A number of colors with different profiles are extracted from the image: 

Vibrant
Vibrant Dark
Vibrant Light
Muted
Muted Dark
Muted Light

These can be retrieved via the appropriate getter method.

Instances are created with a PaletteBuilder which supports several options to tweak the generated Palette.

func (*Palette) ColorForTarget 

func (p *Palette) ColorForTarget(target *Target, defaultColor uint32) uint32

Returns the selected color for the given target from the palette as an RGB packed int.

func (*Palette) DarkMutedColor 

func (p *Palette) DarkMutedColor(defaultColor uint32) uint32

Returns a muted and dark color from the palette as an RGB packed int.

func (*Palette) DarkMutedSwatch 

func (p *Palette) DarkMutedSwatch() *Swatch

Returns a muted and dark swatch from the palette. Might be nil.

func (*Palette) DarkVibrantColor 

func (p *Palette) DarkVibrantColor(defaultColor uint32) uint32

Returns a dark and vibrant color from the palette as an RGB packed int.

func (*Palette) DarkVibrantSwatch 

func (p *Palette) DarkVibrantSwatch() *Swatch

Returns a dark and vibrant swatch from the palette. Might be nil.

func (*Palette) LightMutedColor 

func (p *Palette) LightMutedColor(defaultColor uint32) uint32

Returns a muted and light color from the palette as an RGB packed int.

func (*Palette) LightMutedSwatch 

func (p *Palette) LightMutedSwatch() *Swatch

Returns a muted and light swatch from the palette. Might be nil.

func (*Palette) LightVibrantColor 

func (p *Palette) LightVibrantColor(defaultColor uint32) uint32

Returns a light and vibrant color from the palette as an RGB packed int.

func (*Palette) LightVibrantSwatch 

func (p *Palette) LightVibrantSwatch() *Swatch

Returns a light and vibrant swatch from the palette. Might be nil.

func (*Palette) MutedColor 

func (p *Palette) MutedColor(defaultColor uint32) uint32

Returns a muted color from the palette as an RGB packed int.

func (*Palette) MutedSwatch 

func (p *Palette) MutedSwatch() *Swatch

Returns a muted swatch from the palette. Might be nil.

func (*Palette) SwatchForTarget 

func (p *Palette) SwatchForTarget(target *Target) *Swatch

Returns the selected swatch for the given target from the palette, or nil if one could not be found.

func (*Palette) Swatches 

func (p *Palette) Swatches() []*Swatch

Returns all of the swatches which make up the palette.

func (*Palette) Targets 

func (p *Palette) Targets() []*Target

Returns the targets used to generate this palette.

func (*Palette) VibrantColor 

func (p *Palette) VibrantColor(defaultColor uint32) uint32

Returns the most vibrant color in the palette as an RGB packed int.

func (*Palette) VibrantSwatch 

func (p *Palette) VibrantSwatch() *Swatch

Returns the most vibrant swatch in the palette. Might be nil.

type PaletteBuilder 

type PaletteBuilder struct {
	// contains filtered or unexported fields
}

PaletteBuilder is used for generating Palette instances.

Example 
file, _ := os.Open("test_files/1.jpg")
decodedImage, _, _ := image.Decode(file)
palette := NewPaletteBuilder(decodedImage).Generate()
// Iterate over the swatches in the palette...
for _, swatch := range palette.Swatches() {
	fmt.Printf("Swatch has color %v and population %d\n", swatch.RGBAInt(), swatch.Population())
}
for _, target := range palette.Targets() {
	_ = palette.SwatchForTarget(target)
	// Do something with the swatch for a given target...
}

Output:
Example (MaximumColorCount) 
file, _ := os.Open("test_files/1.jpg")
decodedImage, _, _ := image.Decode(file)
// Use a custom color count.
palette := NewPaletteBuilder(decodedImage).MaximumColorCount(32).Generate()
// Iterate over the swatches in the palette...
for _, swatch := range palette.Swatches() {
	fmt.Printf("Swatch has color %v and population %d\n", swatch.RGBAInt(), swatch.Population())
}
for _, target := range palette.Targets() {
	_ = palette.SwatchForTarget(target)
	// Do something with the swatch for a given target...
}

Output:
Example (ResizeImageArea) 
file, _ := os.Open("test_files/1.jpg")
decodedImage, _, _ := image.Decode(file)
// Use a custom resize image area and scaler.
palette := NewPaletteBuilder(decodedImage).ResizeImageArea(160 * 160).Scaler(draw.CatmullRom).Generate()
// Iterate over the swatches in the palette...
for _, swatch := range palette.Swatches() {
	fmt.Printf("Swatch has color %v and population %d\n", swatch.RGBAInt(), swatch.Population())
}
for _, target := range palette.Targets() {
	_ = palette.SwatchForTarget(target)
	// Do something with the swatch for a given target...
}

Output:

func NewPaletteBuilder 

func NewPaletteBuilder(image image.Image) *PaletteBuilder

NewPaletteBuilder creates a new PaletteBuilder for an image.

func (*PaletteBuilder) AddFilter 

func (b *PaletteBuilder) AddFilter(filter Filter) *PaletteBuilder

Add a filter to be able to have fine grained control over which colors are allowed in the resulting palette.

func (*PaletteBuilder) AddTarget 

func (b *PaletteBuilder) AddTarget(target *Target) *PaletteBuilder

Add a target profile to be generated in the palette.

You can retrieve the result via Palette#getSwatchForTarget(Target).

func (*PaletteBuilder) ClearFilters 

func (b *PaletteBuilder) ClearFilters() *PaletteBuilder

Clear all added filters. This includes any default filters added automatically.

func (*PaletteBuilder) ClearRegion 

func (b *PaletteBuilder) ClearRegion() *PaletteBuilder

Clear a previously specified region.

func (*PaletteBuilder) ClearTargets 

func (b *PaletteBuilder) ClearTargets() *PaletteBuilder

Clear all added targets. This includes any default targets added automatically.

func (*PaletteBuilder) Generate 

func (b *PaletteBuilder) Generate() *Palette

Generate and return the Palette.

func (*PaletteBuilder) MaximumColorCount 

func (b *PaletteBuilder) MaximumColorCount(colors uint32) *PaletteBuilder

Set the maximum number of colors to use in the quantization step.

Good values for depend on the source image type. For landscapes, good values are in the range 10-16. For images which are largely made up of people's faces then this value should be increased to ~24.

func (*PaletteBuilder) Region 

func (b *PaletteBuilder) Region(region image.Rectangle) *PaletteBuilder

Set a region of the image to be used exclusively when calculating the palette.

func (*PaletteBuilder) ResizeImageArea 

func (b *PaletteBuilder) ResizeImageArea(area uint64) *PaletteBuilder

Set the resize value. If the image's area is greater than the value specified, then the image will be resized so that it's area matches the provided area. If the image is smaller or equal, the original is used as-is.

This value has a large effect on the processing time. The larger the resized image is, the greater time it will take to generate the palette. The smaller the image is, the more detail is lost in the resulting image and thus less precision for color selection.

A value of 0 can be used to disable resizing.

func (*PaletteBuilder) Scaler 

func (b *PaletteBuilder) Scaler(scaler draw.Scaler) *PaletteBuilder

Specify the scaling function used to resize an image. Set to nil to disable resizing.

type PriorityQueue 

type PriorityQueue interface {
	Offer(items ...interface{})
	Poll() interface{}
	Len() int
}

A PriorityQueue implements heap.Interface and holds items.

func NewPriorityQueue 

func NewPriorityQueue(initialCapacity uint32, priorityFunction func(interface{}) uint32) PriorityQueue

NewPriorityQueue creates a new PriorityQueue with a given capacity and priority function.

type QuantizedColor 

type QuantizedColor uint16

QuantizedColor represents a reduced RGB color space.

func (QuantizedColor) ApproximateBlue 

func (q QuantizedColor) ApproximateBlue() uint8

ApproximateBlue is the approximate blue component of a quantized color.

func (QuantizedColor) ApproximateGreen 

func (q QuantizedColor) ApproximateGreen() uint8

ApproximateGreen is the approximate green component of a quantized color.

func (QuantizedColor) ApproximateRGBA 

func (q QuantizedColor) ApproximateRGBA() uint32

ApproximateRGBA is the approximate RGBA value of the quantized color.

func (QuantizedColor) ApproximateRed 

func (q QuantizedColor) ApproximateRed() uint8

ApproximateRed is the approximate red component of the quantized color.

func (QuantizedColor) QuantizedBlue 

func (q QuantizedColor) QuantizedBlue() uint8

QuantizedBlue is the blue component of a quantized color.

func (QuantizedColor) QuantizedGreen 

func (q QuantizedColor) QuantizedGreen() uint8

QuantizedGreen is the green component of a quantized color.

func (QuantizedColor) QuantizedRed 

func (q QuantizedColor) QuantizedRed() uint8

QuantizedRed is the red component of the quantized color.

func (QuantizedColor) RGBA 

func (q QuantizedColor) RGBA() (uint32, uint32, uint32, uint32)

RGBA implements the color.Color interface.

func (QuantizedColor) SwapRedBlue 

func (q QuantizedColor) SwapRedBlue() QuantizedColor

SwapRedBlue returns a new QuantizedColor whose red and blue color components have been swapped.

func (QuantizedColor) SwapRedGreen 

func (q QuantizedColor) SwapRedGreen() QuantizedColor

SwapRedGreen returns a new QuantizedColor whose red and green color components have been swapped.

type QuantizedColorSlice 

type QuantizedColorSlice []QuantizedColor

QuantizedColorSlice attaches the methods of sort.Interface to []QuantizedColor, sorting in increasing order.

func (QuantizedColorSlice) Len 

func (s QuantizedColorSlice) Len() int

func (QuantizedColorSlice) Less 

func (s QuantizedColorSlice) Less(i, j int) bool

func (QuantizedColorSlice) Swap 

func (s QuantizedColorSlice) Swap(i, j int)

type RGBAInt 

type RGBAInt uint32

RGBAInt represents a packed RGBA color.

func (RGBAInt) PackedRGB 

func (c RGBAInt) PackedRGB() uint32

PackedRGB is the packed int representing the RGB value (ignores the alpha channel).

func (RGBAInt) PackedRGBA 

func (c RGBAInt) PackedRGBA() uint32

PackedRGBA is the packed int representing the RGBA value.

func (RGBAInt) RGBA 

func (c RGBAInt) RGBA() (uint32, uint32, uint32, uint32)

RGBA implements the color.Color interface.

func (RGBAInt) String 

func (c RGBAInt) String() string

type Scorer 

type Scorer interface {
	// Score returns the score for a Swatch.
	Score(*Swatch) float64
}

Scorer used to score a Swatch for a Target.

func NewDefaultScorer 

func NewDefaultScorer(target Target, maxPopulation uint32) Scorer

NewDefaultScorer creates a new default scorer.

type ScorerFactory 

type ScorerFactory func(Target, []*Swatch) Scorer

ScorerFactory creates a Scorer. 

var (
	// A function which generates a Scorer a target.
	DefaultScorerFactory ScorerFactory
)

The default scorer factory.

type SubImager 

type SubImager interface {
	SubImage(r image.Rectangle) image.Image
}

SubImager is a utility interface for an image.Image that can extract a sub-image.

type Swatch 

type Swatch struct {
	// contains filtered or unexported fields
}

Swatch represents a color swatch generated from an image's palette.

func NewSwatch 

func NewSwatch(color color.Color, population uint32) *Swatch

NewSwatch creates a new Swatch from a color and population.

func (Swatch) Color 

func (s Swatch) Color() color.Color

Color returns this swatch's color value.

func (*Swatch) HSL 

func (s *Swatch) HSL() HSL

HSL returns this swatch's color value as an HSL.

func (Swatch) Population 

func (s Swatch) Population() uint32

Population returns the number of pixels represented by this swatch.

func (*Swatch) RGBAInt 

func (s *Swatch) RGBAInt() RGBAInt

RGBAInt returns this swatch's color value as an RGBAInt.

type Target 

type Target struct {
	// contains filtered or unexported fields
}

Target allows custom selection of colors in a Palette's generation. Instances can be created via TargetBuilder.

To use the target, use the PaletteBuilder#addTarget(Target) API when building a Palette. 

var (
	// A target which has the characteristics of a vibrant color which is light in luminance.
	LightVibrant *Target
	// A target which has the characteristics of a vibrant color which is neither light or dark.
	Vibrant *Target
	// A target which has the characteristics of a vibrant color which is dark in luminance.
	DarkVibrant *Target
	// A target which has the characteristics of a muted color which is light in luminance.
	LightMuted *Target
	// A target which has the characteristics of a muted color which is neither light or dark.
	Muted *Target
	// A target which has the characteristics of a muted color which is dark in luminance.
	DarkMuted *Target
)

The default targets.

func (Target) IsExclusive 

func (t Target) IsExclusive() bool

Returns whether any color selected for this target is exclusive for this target only.

If false, then the color can be selected for other targets.

func (Target) MaximumLightness 

func (t Target) MaximumLightness() float64

The maximum lightness value for this target.

func (Target) MaximumSaturation 

func (t Target) MaximumSaturation() float64

The maximum saturation value for this target.

func (Target) MinimumLightness 

func (t Target) MinimumLightness() float64

The minimum lightness value for this target.

func (Target) MinimumSaturation 

func (t Target) MinimumSaturation() float64

The minimum saturation value for this target.

func (Target) Scorer 

func (t Target) Scorer(swatches []*Swatch) Scorer

Returns a Scorer for the target.

func (Target) String 

func (t Target) String() string

func (Target) TargetLightness 

func (t Target) TargetLightness() float64

The target lightness value for this target.

func (Target) TargetSaturation 

func (t Target) TargetSaturation() float64

The target saturation value for this target.

type TargetBuilder 

type TargetBuilder struct {
	// contains filtered or unexported fields
}

TargetBuilder is used for generating Target instances.

func NewTargetBuilder 

func NewTargetBuilder() *TargetBuilder

NewTargetBuilder creates a new TargetBuilder from scratch.

func NewTargetBuilderFromTarget 

func NewTargetBuilderFromTarget(target *Target) *TargetBuilder

NewTargetBuilderFromTarget creates a new TargetBuilder based on an existing Target.

func (*TargetBuilder) Build 

func (b *TargetBuilder) Build() *Target

Build returns a copy of the Target.

func (*TargetBuilder) IsExclusive 

func (b *TargetBuilder) IsExclusive(exclusive bool) *TargetBuilder

Set whether any color selected for this target is exclusive to this target only. Defaults to true.

func (*TargetBuilder) MaximumLightness 

func (b *TargetBuilder) MaximumLightness(value float64) *TargetBuilder

Set the maximum lightness value for this target.

func (*TargetBuilder) MaximumSaturation 

func (b *TargetBuilder) MaximumSaturation(value float64) *TargetBuilder

Set the maximum saturation value for this target.

func (*TargetBuilder) MinimumLightness 

func (b *TargetBuilder) MinimumLightness(value float64) *TargetBuilder

Set the minimum lightness value for this target.

func (*TargetBuilder) MinimumSaturation 

func (b *TargetBuilder) MinimumSaturation(value float64) *TargetBuilder

Set the minimum saturation value for this target.

func (*TargetBuilder) ScorerFactory 

func (b *TargetBuilder) ScorerFactory(factory ScorerFactory) *TargetBuilder

Set the ScorerFactory for the target. The ScorerFactory is used to generate a Scorer for a target from a slice of swatches.

func (*TargetBuilder) TargetLightness 

func (b *TargetBuilder) TargetLightness(value float64) *TargetBuilder

Set the target/ideal lightness value for this target.

func (*TargetBuilder) TargetSaturation 

func (b *TargetBuilder) TargetSaturation(value float64) *TargetBuilder

Set the target/ideal saturation value for this target.

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