func main() {
// (A file with this name is output by the Go solution to the task
// "Bitmap/Read an image through a pipe," but of course any 8-bit
// P6 PPM file should work.)
b, err := raster.ReadPpmFile("pipein.ppm")
if err != nil {
fmt.Println(err)
return
}
g := b.Grmap()
h := g.Histogram(0)
// compute median
lb, ub := 0, len(h)-1
var lSum, uSum int
for lb <= ub {
if lSum+h[lb] < uSum+h[ub] {
lSum += h[lb]
lb++
} else {
uSum += h[ub]
ub--
}
}
// apply threshold and write output file
g.Threshold(uint16(ub * math.MaxUint16 / len(h)))
err = g.Bitmap().WritePpmFile("threshold.ppm")
if err != nil {
fmt.Println(err)
}
}
func main() {
// Example file used here is Lenna50.jpg from the task "Percentage
// difference between images" converted with with the command
// convert Lenna50.jpg -colorspace gray Lenna50.ppm
// It shows very obvious compression artifacts when viewed at higher
// zoom factors.
b, err := raster.ReadPpmFile("Lenna50.ppm")
if err != nil {
fmt.Println(err)
return
}
g0 = b.Grmap()
w, h := g0.Extent()
g1 = raster.NewGrmap(w, h)
for y := 0; y < h; y++ {
for x := 0; x < w; x++ {
g1.SetPx(x, y, median(x, y))
}
}
// side by side comparison with input file shows compression artifacts
// greatly smoothed over, although at some loss of contrast.
err = g1.Bitmap().WritePpmFile("median.ppm")
if err != nil {
fmt.Println(err)
}
}
func main() {
b, err := raster.ReadPpmFile("Unfilledcirc.ppm")
if err != nil {
fmt.Println(err)
return
}
b.Flood(200, 200, raster.Pixel{127, 0, 0})
err = b.WritePpmFile("flood.ppm")
if err != nil {
fmt.Println(err)
return
}
}
func main() {
// (A file with this name is output by the Go solution to the task
// "Bitmap/Read an image through a pipe," but of course any 8-bit
// P6 PPM file should work.)
b, err := raster.ReadPpmFile("pipein.ppm")
if err != nil {
fmt.Println(err)
return
}
b = b.Grmap().Bitmap()
err = b.WritePpmFile("grayscale.ppm")
if err != nil {
fmt.Println(err)
}
}
func main() {
// Example file used here is Lenna100.jpg from the task "Percentage
// difference between images" converted with with the command
// convert Lenna100.jpg -colorspace gray Lenna100.ppm
b, err := raster.ReadPpmFile("Lenna100.ppm")
if err != nil {
fmt.Println(err)
return
}
g0 := b.Grmap()
g1 := g0.KernelFilter3(blur)
err = g1.Bitmap().WritePpmFile("blur.ppm")
if err != nil {
fmt.Println(err)
}
}