Hough transform: Difference between revisions
Go solution
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}</lang>
This program takes a pnm file (binary, either P5 or P6) and does the transformation, then dump output onto stdout. Sample images below are output from the pentagram; sample lines with added noise; output of processing that. Both output were with 1.5 gamma.
=={{header|Go}}==
[[file:GoHough.png|right|thumb|Output png]]
{{trans|Python}}
<lang go>package main
import (
"fmt"
"image"
"image/color"
"image/draw"
"image/png"
"math"
"os"
)
func hough(im image.Image, ntx, mry int) draw.Image {
nimx := im.Bounds().Max.X
mimy := im.Bounds().Max.Y
mry = int(mry/2) * 2
him := image.NewGray(image.Rect(0, 0, ntx, mry))
draw.Draw(him, him.Bounds(), image.NewUniform(color.White),
image.ZP, draw.Src)
rmax := math.Hypot(float64(nimx), float64(mimy))
dr := rmax / float64(mry/2)
dth := math.Pi / float64(ntx)
for jx := 0; jx < nimx; jx++ {
for iy := 0; iy < mimy; iy++ {
col := color.GrayModel.Convert(im.At(jx, iy)).(color.Gray)
if col.Y == 255 {
continue
}
for jtx := 0; jtx < ntx; jtx++ {
th := dth * float64(jtx)
r := float64(jx)*math.Cos(th) + float64(iy)*math.Sin(th)
iry := mry/2 - int(math.Floor(r/dr+.5))
col = him.At(jtx, iry).(color.Gray)
if col.Y > 0 {
col.Y--
him.SetGray(jtx, iry, col)
}
}
}
}
return him
}
func main() {
f, err := os.Open("Pentagon.png")
if err != nil {
fmt.Println(err)
return
}
pent, err := png.Decode(f)
if err != nil {
fmt.Println(err)
return
}
if err = f.Close(); err != nil {
fmt.Println(err)
}
h := hough(pent, 460, 360)
if f, err = os.Create("hough.png"); err != nil {
fmt.Println(err)
return
}
if err = png.Encode(f, h); err != nil {
fmt.Println(err)
}
if cErr := f.Close(); cErr != nil && err == nil {
fmt.Println(err)
}
}</lang>
=={{header|J}}==
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