Golang - Getting the dimensions of an image. jpg, jpeg, png

images_dimensions.go

package main

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

func main() {
    width, height := getImageDimension("rainy.jpg")
    fmt.Println("Width:", width, "Height:", height)
}

func getImageDimension(imagePath string) (int, int) {
    file, err := os.Open(imagePath)
    if err != nil {
        fmt.Fprintf(os.Stderr, "%v\n", err)
    }

    image, _, err := image.DecodeConfig(file)
    if err != nil {
        fmt.Fprintf(os.Stderr, "%s: %v\n", imagePath, err)
    }
    return image.Width, image.Height
}

If you use exiftool to inspect some images, they may have a property named Orientation/Rotation, which tells you how to rotate that image before displaying. A 4(width)x3(height) image may be displayed as a portrait. After having noticed this, the image package is not suitable for calculating image dimensions, e.g. for putting it on html page with <img width="" height="">.

$ exiftool -json -ImageSize -Orientation IMG_0695.JPG
[{
  "SourceFile": "IMG_0695.JPG",
  "ImageSize": "4032x3024",
  "Orientation": "Rotate 90 CW"
}]