binimg

binimg - Binary images in Go

binimg package proposes an in-memory binary image format, that is an image that has only two possible values for each pixel. In this package, we refer to those 2 colors as binimg.On and binimg.Off, that respectively convert (via binimg.Model) to the standard Go colors color.White and color.Black. binimg.Model implements the color.Model interface.

Such images are also referred to as bi-level, or two-level.

binimg.Binary implements the standard Go image.Image and draw.Image.

A pixel could be stored as a single bit, but as the main goal of this package is fast manipulation of binary images, binimg.Bit, the underlying pixel data type manipulated by binimg.Binary image, is 1 byte wide.

Binary are instantiated by the following functions:

func New(r image.Rectangle, p Palette) *Binary
func NewFromImage(src image.Image, p Palette) *Binary

TODO: REMOVE (there is no more palette, but show an exemple of conversion from a color image to a binary one, with standard color model and maybe how to use a custom color model by subclassing/composition and providing a new color model... if that seems useful) remove all references to binimg.Black and binimg.White

BlackAndWhite predefined Palette

BlackAndWhiteHighThreshold predefined Palette

Custom Palette

Usage

• Create and modify new binary image

package main

import (
	"image"
	"image/color"

	"github.com/arl/imgtools/binimg"
)

func main() {
	// create a new image (prefilled with OffColor: black)
	bin := binimg.New(image.Rect(0, 0, 128, 128), binimg.BlackAndWhite)

	// set a pixel to OnColor: White
	bin.SetBit(10, 0, binimg.On)

	// set a pixel, converting original color with BlackAndWhite Palette
	bin.Set(10, 0, color.RGBA{127, 23, 98, 255})

	// set rectangular region to White
	bin.SetRect(image.Rect(32, 32, 64, 64), binimg.On)
}

• Convert an existing image.Image into black and white binary image

package main

import "github.com/arl/binimg"

func main() {
	// load image ("color-gopher.png")
	// ...
	bin := binimg.NewFromImage(img)

	// save image ("black&white-gopher.png")
	// ...
}

• Use a custom binimg.Palette (i.e color.Model)

import (
	"image"
	"image/color"

	"github.com/arl/imgtools/binimg"
)

func main() {
	var img image.Image

	// ... decode image

	// create
	palette := binimg.Palette{
		OnColor:   color.RGBA{255, 0, 0, 255},
		OffColor:  color.RGBA{0, 0, 255, 255},
		Threshold: 97,
	}
	bin := binimg.NewFromImage(img, palette)

	// ... encode image
}