Quickstart: Create an image classification project with the Custom Vision Python SDK

This article provides information and sample code to help you get started using the Custom Vision SDK with Python to build an image classification model. After it's created, you can add tags, upload images, train the project, obtain the project's default prediction endpoint URL, and use the endpoint to programmatically test an image. Use this example as a template for building your own Python application. If you wish to go through the process of building and using a classification model without code, see the browser-based guidance instead.


Install the Custom Vision SDK

To install the Custom Vision service SDK for Python, run the following command in PowerShell:

pip install azure-cognitiveservices-vision-customvision

Get the training and prediction keys

The project needs a valid set of subscription keys in order to interact with the service. To get a set of free trial keys, go to the Custom Vision website and sign in with a Microsoft account. Select the gear icon in the upper right. In the Accounts section, see the values in the Training Key and Prediction Key fields. You will need these later.

Image of the keys UI

Get the sample images

This example uses the images from the samples/vision/images directory of the Cognitive Services Python SDK Samples repo on GitHub. Clone or download this repository to your development environment.

Add the code

Create a new file called sample.py in your preferred project directory.

Create the Custom Vision service project

Add the following code to your script to create a new Custom Vision service project. Insert your subscription keys in the appropriate definitions.

from azure.cognitiveservices.vision.customvision.training import CustomVisionTrainingClient
from azure.cognitiveservices.vision.customvision.training.models import ImageUrlCreateEntry

ENDPOINT = "https://southcentralus.api.cognitive.microsoft.com"

# Replace with a valid key
training_key = "<your training key>"
prediction_key = "<your prediction key>"

trainer = CustomVisionTrainingClient(training_key, endpoint=ENDPOINT)

# Create a new project
print ("Creating project...")
project = trainer.create_project("My New Project")

Create tags in the project

To create classification tags to your project, add the following code to the end of sample.py:

# Make two tags in the new project
hemlock_tag = trainer.create_tag(project.id, "Hemlock")
cherry_tag = trainer.create_tag(project.id, "Japanese Cherry")

Upload and tag images

To add the sample images to the project, insert the following code after the tag creation. This code uploads each image with its corresponding tag. You will need to enter the base image URL path, based on where you downloaded the Cognitive Services Python SDK Samples project.


You'll need to change the path to the images based on where you downloaded the Cognitive Services Python SDK Samples project earlier.

base_image_url = "<path to project>"

print ("Adding images...")
for image_num in range(1,10):
    image_url = base_image_url + "Images/Hemlock/hemlock_{}.jpg".format(image_num)
    trainer.create_images_from_urls(project.id, [ ImageUrlCreateEntry(url=image_url, tag_ids=[ hemlock_tag.id ] ) ])

for image_num in range(1,10):
    image_url = base_image_url + "Images/Japanese Cherry/japanese_cherry_{}.jpg".format(image_num)
    trainer.create_images_from_urls(project.id, [ ImageUrlCreateEntry(url=image_url, tag_ids=[ cherry_tag.id ] ) ])

Train the classifier

This code creates the first iteration in the project and marks it as the default iteration. The default iteration reflects the version of the model that will respond to prediction requests. You should update this each time you retrain the model.

import time

print ("Training...")
iteration = trainer.train_project(project.id)
while (iteration.status != "Completed"):
    iteration = trainer.get_iteration(project.id, iteration.id)
    print ("Training status: " + iteration.status)

# The iteration is now trained. Make it the default project endpoint
trainer.update_iteration(project.id, iteration.id, is_default=True)
print ("Done!")

Get and use the default prediction endpoint

To send an image to the prediction endpoint and retrieve the prediction, add the following code to the end of the file:

from azure.cognitiveservices.vision.customvision.prediction import CustomVisionPredictionClient

# Now there is a trained endpoint that can be used to make a prediction

predictor = CustomVisionPredictionClient(prediction_key, endpoint=ENDPOINT)

test_img_url = base_image_url + "Images/Test/test_image.jpg"
results = predictor.predict_image_url(project.id, iteration.id, url=test_img_url)

# Display the results.
for prediction in results.predictions:
    print ("\t" + prediction.tag_name + ": {0:.2f}%".format(prediction.probability * 100))

Run the application

Run sample.py.

python sample.py

The output of the application should be similar to the following text:

Creating project...
Adding images...
Training status: Training
Training status: Completed
        Hemlock: 93.53%
        Japanese Cherry: 0.01%

You can then verify that the test image (found in <base_image_url>/Images/Test/) is tagged appropriately. You can also go back to the Custom Vision website and see the current state of your newly created project.

Clean up resources

If you wish to implement your own image classification project (or try an object detection project instead), you may want to delete the tree identification project from this example. A free trial allows for two Custom Vision projects.

On the Custom Vision website, navigate to Projects and select the trash can under My New Project.

Screenshot of a panel labelled My New Project with a trash can icon

Next steps

Now you have seen how every step of the image classification process can be done in code. This sample executes a single training iteration, but often you will need to train and test your model multiple times in order to make it more accurate.