bmp-go is a Go package aiming to provide abilities to decode BMP image files having 4, 8, 16, 24 and 32 bits color depths. It supports RLE decoding which might be applied as a compression method to 4 bits and 8 bits BMP images. The decoder outputs an image.Image with an *image.RGBA format.
This could also be used to directly encode an *image.RGBA format and writes it into an io.Writer as a 32 bits RGBA color BMP file. See sample usage.
Sample BMP images with various formats can be found in /images directory. The specifications for encoding and decoding are from https://en.wikipedia.org/wiki/BMP_file_format. The code within this repo is easy to read and modify to suit your needs.
Install with go get -u github.com/dvertx/bmp-go or by manually cloning this repository into $GOPATH/src/github.com/dvertx/
Test both, decoding and encoding, with:
package main
import (
"bufio"
"bytes"
"fmt"
"image/png"
"os"
"github.com/dvertx/bmp-go"
)
func main() {
f, err := os.Open("anyold.bmp")
if err != nil {
fmt.Println("Error:", err)
return
}
defer f.Close()
img, err := bmp.Decode(f)
if err != nil {
fmt.Println("Error:", err)
return
}
pngbuffer := new(bytes.Buffer)
pngwriter := bufio.NewWriter(pngbuffer)
png.Encode(pngwriter, img)
pngwriter.Flush()
err = os.WriteFile("test.png", pngbuffer.Bytes(), 0644)
if err != nil {
fmt.Println("Error:", err)
return
}
out, err := os.Create("newfile.bmp")
if err != nil {
fmt.Println("Error:", err)
return
}
defer out.Close()
err = bmp.Encode(out, img)
if err != nil {
fmt.Println("Error:", err)
return
}
}