riemersma

README

riemersma

riemersma is a Go implementation of Riemersma Dithering based on this example in C

Documentation

Index

• Variables
• type ColorError
• type Drawer
  • func (dr Drawer) Draw(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point)
• type Image
  • func NewImage(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point) Image
• type Op
  • func NewOperation(queueSize int, ratio float64) *Op
  • func (rs *Op) AccumulatedError(numChannel int) ColorError
  • func (rs *Op) Dither(image Image)
  • func (rs *Op) Draw(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point)

Variables

var Riemersma = Drawer{}

Riemersma is a draw.Drawer (similar to draw.FloydSteinberg) which does Riemersma dithering to src image and draws result on dst image

Types

type ColorError

type ColorError []float64

color quantization errors for each channel

type Drawer

type Drawer struct{}

func (Drawer) Draw

func (dr Drawer) Draw(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point)

type Image

type Image interface {
	Size() image.Point                                      // image size
	ColorNumChannels() int                                  // number of color channels
	DitherPixel(x int, y int, accErr ColorError) ColorError // Dither pixel with accumulated error
}

func NewImage

func NewImage(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point) Image

type Op

type Op struct {
	Ratio   float64   // weight ratio between youngest pixel and oldest pixel
	Weights []float64 // pre-calculated weights
	// contains filtered or unexported fields
}

Riemersma Dither Operation. It is not resuable.

func NewOperation

func NewOperation(queueSize int, ratio float64) *Op

Create new Riemersma dither operation with specific queueSize and ratio queueSize is the number of most recent pixel quantization errors to remember ratio is weight ratio between youngest pixel and oldest pixel

func (*Op) AccumulatedError

func (rs *Op) AccumulatedError(numChannel int) ColorError

func (*Op) Dither

func (rs *Op) Dither(image Image)

func (*Op) Draw

func (rs *Op) Draw(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point)