Portable Network Graphics (Legacy MIME)

import magic
# Modern Libmagic will output the standardized 'image/png' rather than the legacy 'x-png'
print(magic.from_file('graphic.png', mime=True)) # Outputs 'image/png'

const mime = require('mime');
// JS libraries resolve .png strictly to the IANA standard image/png
console.log(mime.getType('graphic.png')); // Outputs 'image/png'

import (
    "bytes"
    "net/http"
)
// Native Go HTTP detection reads the PNG magic bytes and returns the standard MIME
// mime := http.DetectContentType(buf) // Returns "image/png"

// Example of normalizing the legacy MIME type during a file upload in PHP
$mime = $_FILES['upload']['type'];
if ($mime === 'image/x-png') {
    $mime = 'image/png';
}
echo $mime;