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Object Detection

Run inference on your object detection models hosted on Roboflow.
Python
cURL
Javascript
Swift/iOS
Android
Ruby
PHP
Go
.NET
Elixir
To run inference through our hosted API using Python, use the roboflow Python package:
from roboflow import Roboflow
rf = Roboflow(api_key="API_KEY")
project = rf.workspace().project("MODEL_ENDPOINT")
model = project.version(VERSION).model
​
# infer on a local image
print(model.predict("your_image.jpg", confidence=40, overlap=30).json())
​
# visualize your prediction
# model.predict("your_image.jpg", confidence=40, overlap=30).save("prediction.jpg")
​
# infer on an image hosted elsewhere
# print(model.predict("URL_OF_YOUR_IMAGE", hosted=True, confidence=40, overlap=30).json())
​

Linux or MacOS

Retrieving JSON predictions for a local file called YOUR_IMAGE.jpg:
base64 YOUR_IMAGE.jpg | curl -d @- \
"https://detect.roboflow.com/your-model/42?api_key=YOUR_KEY"
Inferring on an image hosted elsewhere on the web via its URL (don't forget to URL encode it):
curl -X POST "https://detect.roboflow.com/your-model/42?\
api_key=YOUR_KEY&\
image=https%3A%2F%2Fi.imgur.com%2FPEEvqPN.png"

Windows

You will need to install curl for Windows and GNU's base64 tool for Windows. The easiest way to do this is to use the git for Windows installer which also includes the curl and base64 command line tools when you select "Use Git and optional Unix tools from the Command Prompt" during installation.
Then you can use the same commands as above.

Node.js

We're using axios to perform the POST request in this example so first run npm install axios to install the dependency.

Inferring on a Local Image

const axios = require("axios");
const fs = require("fs");
​
const image = fs.readFileSync("YOUR_IMAGE.jpg", {
encoding: "base64"
});
​
axios({
method: "POST",
url: "https://detect.roboflow.com/your-model/42",
params: {
api_key: "YOUR_KEY"
},
data: image,
headers: {
"Content-Type": "application/x-www-form-urlencoded"
}
})
.then(function(response) {
console.log(response.data);
})
.catch(function(error) {
console.log(error.message);
});

Inferring on an Image Hosted Elsewhere via URL

const axios = require("axios");
​
axios({
method: "POST",
url: "https://detect.roboflow.com/your-model/42",
params: {
api_key: "YOUR_KEY",
image: "https://i.imgur.com/PEEvqPN.png"
}
})
.then(function(response) {
console.log(response.data);
})
.catch(function(error) {
console.log(error.message);
});

Web

We have realtime on-device inference available via roboflow.js; see the documentation here.

Swift

Inferring on a Local Image

import UIKit
​
// Load Image and Convert to Base64
let image = UIImage(named: "your-image-path") // path to image to upload ex: image.jpg
let imageData = image?.jpegData(compressionQuality: 1)
let fileContent = imageData?.base64EncodedString()
let postData = fileContent!.data(using: .utf8)
​
// Initialize Inference Server Request with API_KEY, Model, and Model Version
var request = URLRequest(url: URL(string: "https://detect.roboflow.com/your-model/your-model-version?api_key=YOUR_APIKEY&name=YOUR_IMAGE.jpg")!,timeoutInterval: Double.infinity)
request.addValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpMethod = "POST"
request.httpBody = postData
​
// Execute Post Request
URLSession.shared.dataTask(with: request, completionHandler: { data, response, error in
// Parse Response to String
guard let data = data else {
print(String(describing: error))
return
}
// Convert Response String to Dictionary
do {
let dict = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any]
} catch {
print(error.localizedDescription)
}
// Print String Response
print(String(data: data, encoding: .utf8)!)
}).resume()

Objective C

​Click here to request an Objective-C snippet.​

Kotlin

Inferring on a Local Image

import java.io.*
import java.net.HttpURLConnection
import java.net.URL
import java.nio.charset.StandardCharsets
import java.util.*
​
fun main() {
// Get Image Path
val filePath = System.getProperty("user.dir") + System.getProperty("file.separator") + "YOUR_IMAGE.jpg"
val file = File(filePath)
​
// Base 64 Encode
val encodedFile: String
val fileInputStreamReader = FileInputStream(file)
val bytes = ByteArray(file.length().toInt())
fileInputStreamReader.read(bytes)
encodedFile = String(Base64.getEncoder().encode(bytes), StandardCharsets.US_ASCII)
val API_KEY = "" // Your API Key
val MODEL_ENDPOINT = "dataset/v" // Set model endpoint (Found in Dataset URL)
​
// Construct the URL
val uploadURL ="https://detect.roboflow.com/" + MODEL_ENDPOINT + "?api_key=" + API_KEY + "&name=YOUR_IMAGE.jpg";
​
// Http Request
var connection: HttpURLConnection? = null
try {
// Configure connection to URL
val url = URL(uploadURL)
connection = url.openConnection() as HttpURLConnection
connection.requestMethod = "POST"
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded")
connection.setRequestProperty("Content-Length",
Integer.toString(encodedFile.toByteArray().size))
connection.setRequestProperty("Content-Language", "en-US")
connection.useCaches = false
connection.doOutput = true
​
//Send request
val wr = DataOutputStream(
connection.outputStream)
wr.writeBytes(encodedFile)
wr.close()
​
// Get Response
val stream = connection.inputStream
val reader = BufferedReader(InputStreamReader(stream))
var line: String?
while (reader.readLine().also { line = it } != null) {
println(line)
}
reader.close()
} catch (e: Exception) {
e.printStackTrace()
} finally {
connection?.disconnect()
}
}
main()

Inferring on an Image Hosted Elsewhere via URL

import java.io.BufferedReader
import java.io.DataOutputStream
import java.io.InputStreamReader
import java.net.HttpURLConnection
import java.net.URL
import java.net.URLEncoder
​
fun main() {
val imageURL = "https://i.imgur.com/PEEvqPN.png" // Replace Image URL
val API_KEY = "" // Your API Key
val MODEL_ENDPOINT = "dataset/v" // Set model endpoint
​
// Upload URL
val uploadURL = "https://detect.roboflow.com/" + MODEL_ENDPOINT + "?api_key=" + API_KEY + "&image=" + URLEncoder.encode(imageURL, "utf-8");
​
// Http Request
var connection: HttpURLConnection? = null
try {
// Configure connection to URL
val url = URL(uploadURL)
connection = url.openConnection() as HttpURLConnection
connection.requestMethod = "POST"
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded")
connection.setRequestProperty("Content-Length", Integer.toString(uploadURL.toByteArray().size))
connection.setRequestProperty("Content-Language", "en-US")
connection.useCaches = false
connection.doOutput = true
​
// Send request
val wr = DataOutputStream(connection.outputStream)
wr.writeBytes(uploadURL)
wr.close()
​
// Get Response
val stream = URL(uploadURL).openStream()
val reader = BufferedReader(InputStreamReader(stream))
var line: String?
while (reader.readLine().also { line = it } != null) {
println(line)
}
reader.close()
} catch (e: Exception) {
e.printStackTrace()
} finally {
connection?.disconnect()
}
}
​
main()

Java

Inferring on a Local Image

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
​
public class InferenceLocal {
public static void main(String[] args) throws IOException {
// Get Image Path
String filePath = System.getProperty("user.dir") + System.getProperty("file.separator") + "YOUR_IMAGE.jpg";
File file = new File(filePath);
​
// Base 64 Encode
String encodedFile;
FileInputStream fileInputStreamReader = new FileInputStream(file);
byte[] bytes = new byte[(int) file.length()];
fileInputStreamReader.read(bytes);
encodedFile = new String(Base64.getEncoder().encode(bytes), StandardCharsets.US_ASCII);
​
String API_KEY = ""; // Your API Key
String MODEL_ENDPOINT = "dataset/v"; // model endpoint
​
// Construct the URL
String uploadURL = "https://detect.roboflow.com/" + MODEL_ENDPOINT + "?api_key=" + API_KEY
+ "&name=YOUR_IMAGE.jpg";
​
// Http Request
HttpURLConnection connection = null;
try {
// Configure connection to URL
URL url = new URL(uploadURL);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
​
connection.setRequestProperty("Content-Length", Integer.toString(encodedFile.getBytes().length));
connection.setRequestProperty("Content-Language", "en-US");
connection.setUseCaches(false);
connection.setDoOutput(true);
​
// Send request
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.writeBytes(encodedFile);
wr.close();
​
// Get Response
InputStream stream = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
reader.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
}
​
}
​
}

Inferring on an Image Hosted Elsewhere via URL

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
​
public class InferenceHosted {
public static void main(String[] args) {
String imageURL = "https://i.imgur.com/PEEvqPN.png"; // Replace Image URL
String API_KEY = ""; // Your API Key
String MODEL_ENDPOINT = "dataset/v"; // model endpoint
​
// Upload URL
String uploadURL = "https://detect.roboflow.com/" + MODEL_ENDPOINT + "?api_key=" + API_KEY + "&image="
+ URLEncoder.encode(imageURL, StandardCharsets.UTF_8);
​
// Http Request
HttpURLConnection connection = null;
try {
// Configure connection to URL
URL url = new URL(uploadURL);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
​
connection.setRequestProperty("Content-Length", Integer.toString(uploadURL.getBytes().length));
connection.setRequestProperty("Content-Language", "en-US");
connection.setUseCaches(false);
connection.setDoOutput(true);
​
// Send request
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.writeBytes(uploadURL);
wr.close();
​
// Get Response
InputStream stream = new URL(uploadURL).openStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
reader.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
}
}
}

Gemfile

Gemfile
source "https://rubygems.org"
​
gem "httparty", "~> 0.18.1"
gem "base64", "~> 0.1.0"
gem "cgi", "~> 0.2.1"

Gemfile.lock

Gemfile.lock
GEM
remote: https://rubygems.org/
specs:
base64 (0.1.0)
cgi (0.2.1)
httparty (0.18.1)
mime-types (~> 3.0)
multi_xml (>= 0.5.2)
mime-types (3.3.1)
mime-types-data (~> 3.2015)
mime-types-data (3.2021.0225)
multi_xml (0.6.0)
​
PLATFORMS
x64-mingw32
x86_64-linux
​
DEPENDENCIES
base64 (~> 0.1.0)
cgi (~> 0.2.1)
httparty (~> 0.18.1)
​
BUNDLED WITH
2.2.15

Inferring on a Local Image

require 'base64'
require 'httparty'
​
encoded = Base64.encode64(File.open("YOUR_IMAGE.jpg", "rb").read)
model_endpoint = "dataset/v" # Set model endpoint
api_key = "" # Your API KEY Here
​
params = "?api_key=" + api_key
+ "&name=YOUR_IMAGE.jpg"
​
response = HTTParty.post(
"https://detect.roboflow.com/" + model_endpoint + params,
body: encoded,
headers: {
'Content-Type' => 'application/x-www-form-urlencoded',
'charset' => 'utf-8'
})
​
puts response
​

Inferring on an Image Hosted Elsewhere via URL

require 'httparty'
require 'cgi'
​
model_endpoint = "dataset/v" # Set model endpoint
api_key = "" # Your API KEY Here
img_url = "https://i.imgur.com/PEEvqPN.png" # Construct the URL
​
img_url = CGI::escape(img_url)
​
params = "?api_key=" + api_key + "&image=" + img_url
​
response = HTTParty.post(
"https://detect.roboflow.com/" + model_endpoint + params,
headers: {
'Content-Type' => 'application/x-www-form-urlencoded',
'charset' => 'utf-8'
})
​
puts response
Inferring on a Local Image
<?php
​
// Base 64 Encode Image
$data = base64_encode(file_get_contents("YOUR_IMAGE.jpg"));
​
$api_key = ""; // Set API Key
$model_endpoint = "dataset/v"; // Set model endpoint (Found in Dataset URL)
​
// URL for Http Request
$url = "https://detect.roboflow.com/" . $model_endpoint
. "?api_key=" . $api_key
. "&name=YOUR_IMAGE.jpg";
​
// Setup + Send Http request
$options = array(
'http' => array (
'header' => "Content-type: application/x-www-form-urlencoded\r\n",
'method' => 'POST',
'content' => $data
));
​
$context = stream_context_create($options);
$result = file_get_contents($url, false, $context);
echo $result;
?>

Inferring on an Image Hosted Elsewhere via URL

<?php
​
$api_key = ""; // Set API Key
$model_endpoint = "dataset/v"; // Set model endpoint (Found in Dataset URL)
$img_url = "https://i.imgur.com/PEEvqPN.png";
​
// URL for Http Request
$url = "https://detect.roboflow.com/" . $model_endpoint
. "?api_key=" . $api_key
. "&image=" . urlencode($img_url);
​
// Setup + Send Http request
$options = array(
'http' => array (
'header' => "Content-type: application/x-www-form-urlencoded\r\n",
'method' => 'POST'
));
​
$context = stream_context_create($options);
$result = file_get_contents($url, false, $context);
echo $result;
?>
Inferring on a Local Image
package main
​
import (
"bufio"
"encoding/base64"
"fmt"
"io/ioutil"
"os"
"net/http"
"strings"
)
​
func main() {
api_key := "" // Your API Key
model_endpoint := "dataset/v" // Set model endpoint
​
// Open file on disk.
f, _ := os.Open("YOUR_IMAGE.jpg")
​
// Read entire JPG into byte slice.
reader := bufio.NewReader(f)
content, _ := ioutil.ReadAll(reader)
​
// Encode as base64.
data := base64.StdEncoding.EncodeToString(content)
uploadURL := "https://detect.roboflow.com/" + model_endpoint + "?api_key=" + api_key + "&name=YOUR_IMAGE.jpg"
​
req, _ := http.NewRequest("POST", uploadURL, strings.NewReader(data))
req.Header.Set("Accept", "application/json")
​
client := &http.Client{}
resp, _ := client.Do(req)
defer resp.Body.Close()
​
bytes, _ := ioutil.ReadAll(resp.Body)
fmt.Println(string(bytes))
​
}

Inferring on an Image Hosted Elsewhere via URL

package main
​
import (
"fmt"
"net/http"
"net/url"
"io/ioutil"
)
​
func main() {
api_key := "" // Your API Key
model_endpoint := "dataset/v" // Set model endpoint
img_url := "https://i.ibb.co/jzr27x0/YOUR-IMAGE.jpg"
​
​
uploadURL := "https://detect.roboflow.com/" + model_endpoint + "?api_key=" + api_key + "&image=" + url.QueryEscape(img_url)
​
req, _ := http.NewRequest("POST", uploadURL, nil)
req.Header.Set("Accept", "application/json")
​
client := &http.Client{}
resp, _ := client.Do(req)
defer resp.Body.Close()
​
bytes, _ := ioutil.ReadAll(resp.Body)
fmt.Println(string(bytes))
​
​
}
Inferring on a Local Image
using System;
using System.IO;
using System.Net;
using System.Text;
​
namespace InferenceLocal
{
class InferenceLocal
{
​
static void Main(string[] args)
{
byte[] imageArray = System.IO.File.ReadAllBytes(@"YOUR_IMAGE.jpg");
string encoded = Convert.ToBase64String(imageArray);
byte[] data = Encoding.ASCII.GetBytes(encoded);
string API_KEY = ""; // Your API Key
string MODEL_ENDPOINT = "dataset/v"; // Set model endpoint
​
// Construct the URL
string uploadURL =
"https://detect.roboflow.com/" + MODEL_ENDPOINT + "?api_key=" + API_KEY
+ "&name=YOUR_IMAGE.jpg";
​
// Service Request Config
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
​
// Configure Request
WebRequest request = WebRequest.Create(uploadURL);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = data.Length;
​
// Write Data
using (Stream stream = request.GetRequestStream())
{
stream.Write(data, 0, data.Length);
}
​
// Get Response
string responseContent = null;
using (WebResponse response = request.GetResponse())
{
using (Stream stream = response.GetResponseStream())
{
using (StreamReader sr99 = new StreamReader(stream))
{
responseContent = sr99.ReadToEnd();
}
}
}
​
Console.WriteLine(responseContent);
​
}
}
}

Inferring on an Image Hosted Elsewhere via URL

using System;
using System.IO;
using System.Net;
using System.Web;
​
namespace InferenceHosted
{
class InferenceHosted
{
static void Main(string[] args)
{
string API_KEY = ""; // Your API Key
string imageURL = "https://i.ibb.co/jzr27x0/YOUR-IMAGE.jpg";
string MODEL_ENDPOINT = "dataset/v"; // Set model endpoint
​
// Construct the URL
string uploadURL =
"https://detect.roboflow.com/" + MODEL_ENDPOINT
+ "?api_key=" + API_KEY
+ "&image=" + HttpUtility.UrlEncode(imageURL);
​
// Service Point Config
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
​
// Configure Http Request
WebRequest request = WebRequest.Create(uploadURL);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = 0;
​
// Get Response
string responseContent = null;
using (WebResponse response = request.GetResponse())
{
using (Stream stream = response.GetResponseStream())
{
using (StreamReader sr99 = new StreamReader(stream))
{
responseContent = sr99.ReadToEnd();
}
}
}
​
Console.WriteLine(responseContent);
​
}
}
}
We are adding code snippets as they are requested by users. If you'd like to integrate the inference API into your Elixir app, please click here to record your upvote.

Response Object Format

The hosted API inference route returns a JSON object containing an array of predictions. Each prediction has the following properties:
  • x = the horizontal center point of the detected object
  • y = the vertical center point of the detected object
  • width = the width of the bounding box
  • height = the height of the bounding box
  • class = the class label of the detected object
  • confidence = the model's confidence that the detected object has the correct label and position coordinates
Here is an example response object from the REST API:
{
"predictions": [
{
"x": 189.5,
"y": 100,
"width": 163,
"height": 186,
"class": "helmet",
"confidence": 0.544
}
],
"image": {
"width": 2048,
"height": 1371
}
}
The image attribute contains the height and width of the image sent for inference. You may need to use these values for bounding box calculations.

Inference API Parameters

post
https://detect.roboflow.com
/:datasetSlug/:versionNumber
Using the Inference API

Drawing a Box from the Inference API JSON Output

Frameworks and packages for rendering bounding boxes can differ in positional formats. Given the response JSON object's properties, a bounding box can always be drawn using some combination of the following rules:
  • the center point will always be (x,y)
  • the corner points (x1, y1) and (x2, y2) can be found using:
    • x1 = x - (width/2)
    • y1 = y - (height/2)
    • x2 = x + (width/2)
    • y2 = y + (height/2)
The corner points approach is a common pattern and seen in libraries such as Pillow when building the box object to render bounding boxes within an Image.
Don't forget to iterate through all detections found when working with predictions!
# example box object from the Pillow library
for bounding_box in detections:
x1 = bounding_box['x'] - bounding_box['width'] / 2
x2 = bounding_box['x'] + bounding_box['width'] / 2
y1 = bounding_box['y'] - bounding_box['height'] / 2
y2 = bounding_box['y'] + bounding_box['height'] / 2
box = (x1, x2, y1, y2)
Last modified 28d ago