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@aclements aclements/scale.go
Created Jun 26, 2015

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Scale down by 2x using x/image/draw
package main
import (
"flag"
"fmt"
"image"
"image/png"
"log"
"os"
"golang.org/x/image/draw"
)
func main() {
var err error
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage: %s input output\n", os.Args[0])
}
flag.Parse()
if flag.NArg() != 2 {
flag.Usage()
os.Exit(2)
}
// Read input file.
f, err := os.Open(os.Args[1])
if err != nil {
log.Fatal(err)
}
defer f.Close()
src, _, err := image.Decode(f)
if err != nil {
log.Fatal(err)
}
// Scale down by a factor of 2.
sb := src.Bounds()
dst := image.NewRGBA(image.Rect(0, 0, sb.Dx()/2, sb.Dy()/2))
draw.BiLinear.Scale(dst, dst.Bounds(), src, sb, draw.Over, nil)
// Write output file.
if f, err = os.Create(os.Args[2]); err != nil {
log.Fatal(err)
}
defer f.Close()
if err := png.Encode(f, dst); err != nil {
log.Fatal(err)
}
}
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