Base64 Encoding

You can provide image data to the Vision API by specifying the URI path to the image, or by sending the image data as base64-encoded text.

Most development environments contain a native "base64" utility to encode a binary image into ASCII text data. To encode an image file:

Linux

    base64 input.jpg > output.txt

Mac OSX

    base64 -i input.jpg -o output.txt

Windows

    C:> Base64.exe -e input.jpg > output.txt

PowerShell

    [Convert]::ToBase64String([IO.File]::ReadAllBytes("./input.jpg")) > output.txt

You can then use this output image data natively within the JSON request:

{
  "requests":[
    {
      "image":{
        "content": "BASE64_ENCODED_DATA"
      },
      "features": [
        {
          "type":"LABEL_DETECTION",
          "maxResults":1
        }
      ]
    }
  ]
}

Each programming language has its own way of base64 encoding image files:

Python

In Python, you can base64-encode image files as follows:

# Import the base64 encoding library.
import base64

# Pass the image data to an encoding function.
def encode_image(image):
  image_content = image.read()
  return base64.b64encode(image_content)

Node.js

In Node.js, you can base64-encode image files as follows:

// Read the file into memory.
var fs = require('fs');
var imageFile = fs.readFileSync('/path/to/file');

// Convert the image data to a Buffer and base64 encode it.
var encoded = Buffer.from(imageFile).toString('base64');

Java

In Java, you can base64-encode image files as follows:

// Import the Base64 encoding library.
import org.apache.commons.codec.binary.Base64;

// Encode the image.
byte[] imageData = Base64.encodeBase64(imageFile.getBytes());

Go

In Go, you can base64-encode image files as follows:

   import (
       "bufio"
       "encoding/base64"
       "io/ioutil"
       "os"
   )

   // Open image file.
   f, _ := os.Open("image.jpg")

   // Read entire image into byte slice.
   reader := bufio.NewReader(f)
   content, _ := ioutil.ReadAll(reader)

   // Encode image as base64.
   base64.StdEncoding.EncodeToString(content)