threshold_random_gallery_gamma.go

package main

import (
	"fmt"
	"image"
	"image/color"
	"image/draw"
	"image/png"
	"math"
	"math/rand"
	"os"
)

func TresholdRandom(img image.Image, t float32, randomRange float32) (image.Image, image.Image, float64) {

    result := image.NewGray(img.Bounds())
    qerr := image.NewGray(img.Bounds())
    var averr float64
    
    for y := img.Bounds().Min.Y; y < img.Bounds().Max.Y; y++ {
        for x := img.Bounds().Min.X; x < img.Bounds().Max.X; x++ {
            r, g, b, _ := img.At(x, y).RGBA()

            v := float32(math.Pow(float64(uint8((r + g + b) / 3)) / 255.0, 2.2))

            randomFactor := randomRange * (rand.Float32() - 0.5)

            newV := v + randomFactor
            
            var final uint8
            if newV > t {
                final = 255
            }  else {
                final = 0
            }

            result.Set(x, y, color.Gray{ final })
            delta := math.Abs(float64(final) - float64(255.0 * v))
            qerr.Set(x, y, color.Gray{ uint8(delta) })
            averr += delta / float64((img.Bounds().Max.X * img.Bounds().Max.Y))
        }
    }

    return result, qerr, averr/255
}

func ThresholdRandomGallery(img image.Image) image.Image {
    rect := img.Bounds()
    gallery := image.NewGray(image.Rect(0, 0, 11 * rect.Dx(), 11 * rect.Dy()))

    var t float32 = 0.0
    var r float32 = 0.0

    width := rect.Dx()
    height := rect.Dy()
    x := 0
    y := 0

    for i := 0; i < 11; i++ {
        for j := 0; j < 11; j++ {

            subImage, _, _ := TresholdRandom(img, t, r)
            rectangle := image.Rect(x, y, x + width, y + height)
            fmt.Println(rectangle, t, r)
            draw.Draw(gallery, rectangle, subImage, image.ZP, draw.Over)

            r += 0.1
            x += width
        }
        r = 0
        x = 0
        t += 0.1
        y += height
    }


    return gallery
}

func main() {
    r, err := os.Open("image.png")
    if err != nil {
        panic(err)
    }

    img, err := png.Decode(r)
    if err != nil {
        panic(err)
    }
    
    //out, qerr, averr := TresholdRandom(img, 0.48, 0.35)
    out := ThresholdRandomGallery(img)

    w, err := os.Create("out.png")
    if err != nil {
        panic(err)
    }

    //w2, err := os.Create("qerr.png")
    //if err != nil {
    //    panic(err)
    //}
    err = png.Encode(w, out)
    //err = png.Encode(w2, qerr)

    if err != nil {
        panic(err)
    }
}