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package main
import (
"image"
"math"
)
func mean(i []int) float64 {
sum := 0
for _, n := range i {
sum += n
}
return float64(sum) / float64(len(i))
}
func stddev(i []int) float64 {
m := mean(i)
var sum float64
for _, n := range i {
sum += (float64(n) - m) * (float64(n) - m)
}
variance := sum / float64(len(i) - 1)
return math.Sqrt(variance)
}
func meanstddev(i []int) (float64, float64) {
m := mean(i)
var sum float64
for _, n := range i {
sum += (float64(n) - m) * (float64(n) - m)
}
variance := float64(sum) / float64(len(i) - 1)
return m, math.Sqrt(variance)
}
// gets the pixel values surrounding a point in the image
func surrounding(img *image.Gray, x int, y int, size int) []int {
b := img.Bounds()
step := size / 2
miny := y - step
if miny < b.Min.Y {
miny = b.Min.Y
}
minx := x - step
if minx < b.Min.X {
minx = b.Min.X
}
maxy := y + step
if maxy > b.Max.Y {
maxy = b.Max.Y
}
maxx := x + step
if maxx > b.Max.X {
maxx = b.Max.X
}
var s []int
for yi := miny; yi <= maxy; yi++ {
for xi := minx; xi <= maxx; xi++ {
s = append(s, int(img.GrayAt(xi, yi).Y))
}
}
return s
}
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