Before you begin

Before you can use the Cloud Vision API, you must enable it for your project:

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.
In the Google Cloud Console, on the project selector page, select or create a Google Cloud project.

Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

Go to project selector
Make sure that billing is enabled for your Cloud project. Learn how to confirm that billing is enabled for your project.
Enable the Cloud Vision API.
Enable the API

Create a service account:
1. In the Cloud Console, go to the Create service account page.
  Go to Create service account
2. Select a project.
3. In the Service account name field, enter a name. The Cloud Console fills in the Service account ID field based on this name.
  
  In the Service account description field, enter a description. For example, Service account for quickstart.
4. Click Create.
5. Click the Select a role field.
  
  Under Quick access, click Basic, then click Owner.
  
  Note: The Role field affects which resources your service account can access in your project. You can revoke these roles or grant additional roles later. In production environments, do not grant the Owner, Editor, or Viewer roles. For more information, see Granting, changing, and revoking access to resources.
6. Click Continue.
7. Click Done to finish creating the service account.
  
  Do not close your browser window. You will use it in the next step.
Create a service account key:
1. In the Cloud Console, click the email address for the service account that you created.
2. Click Keys.
3. Click Add key, then click Create new key.
4. Click Create. A JSON key file is downloaded to your computer.
5. Click Close.
Set the environment variable GOOGLE_APPLICATION_CREDENTIALS to the path of the JSON file that contains your service account key. This variable only applies to your current shell session, so if you open a new session, set the variable again.
Example: Linux or macOS
```
export GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"
```
Replace KEY_PATH with the path of the JSON file that contains your service account key.

For example:
```
export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/service-account-file.json"
```
Example: Windows

For PowerShell:
```
$env:GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"
```
Replace KEY_PATH with the path of the JSON file that contains your service account key.

For example:
```
$env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\username\Downloads\service-account-file.json"
```
For command prompt:
```
set GOOGLE_APPLICATION_CREDENTIALS=KEY_PATH
```
Replace KEY_PATH with the path of the JSON file that contains your service account key.