Golang : Get dimension(width and height) of image file

If you need to open up an image file, be it jpeg, png or gif. Chances are you will need to know the dimension - width and height of the image before manipulating it.

You will have to use image.DecodeConfig() function to get the color model and dimension data.

Here is an example code in Golang on how to get an image dimension - width and height.

 package main

 import (
 "fmt"
 "image"
 "image/jpeg"
 "os"
 )

 func init() {
 // damn important or else At(), Bounds() functions will
 // caused memory pointer error!!
 image.RegisterFormat("jpeg", "jpeg", jpeg.Decode, jpeg.DecodeConfig)
 }

 func main() {
 imgfile, err := os.Open("./img.jpg")

 if err != nil {
 fmt.Println("img.jpg file not found!")
 os.Exit(1)
 }

 defer imgfile.Close()

 // get image height and width with image/jpeg
 // change accordinly if file is png or gif

 imgCfg, _, err := image.DecodeConfig(imgfile)

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 width := imgCfg.Width
 height := imgCfg.Height

 fmt.Println("Width : ", width)
 fmt.Println("Height : ", height)

 }

Sample output :

Width : 760

Height : 479

References :

https://golang.org/pkg/image/#Config

https://golang.org/pkg/image/#DecodeConfig