How I trained a computer vision model on the AWS Free Tier

Esin Saribudak — Fri, 27 Mar 2026 01:20:43 +0000

Last updated: March 26, 2026

Developers hide Easter eggs in code. Filmmakers hide them in scenes. I hid them in AI-generated images and asked Amazon Rekognition to find them.

If you've ever wondered whether AWS Free Tier gives you enough credits to build something cool, this post is for you. I built an Easter egg detector powered by Amazon Rekognition, tested its standard object detection API on 37 images, and trained a custom model, all with my AWS Free Tier credits.

(If you haven't set up a Free Tier account, check out this great guide!)

The idea

I wanted to build a simple and fun app where I can upload a photo and have the app tell me if there's an Easter egg in it. It sounds kind of silly, but the technical problem it maps to — locating a small, specific object in a complex scene — is a foundational one for the field of computer vision.

AWS has a lot of services for different AI/ML use cases, including Amazon Rekognition for computer vision. I learned that organizations like C-SPAN and the NFL use it to understand what's in their images and video. And Amazon Rekognition is available on the AWS Free Tier, which makes experimenting with it easier.

The service gives you different ways to figure out what's in images. The DetectLabels API works out of the box and recognizes thousands of common objects and concepts, everything from aircraft to zucchini to birthday parties. Custom Labels let you train your own computer vision model when the built-in labels fall short. With this project, I wanted to find out where the first one stops being useful and the other is needed.

What I built

The app I built to explore that question is a Streamlit app with two modes. Standard mode sends your image to the DetectLabels API and checks if it returns "Egg" or "Easter Egg" in the labels. Custom Labels mode uses a custom model I trained on my own images. Both draw bounding boxes around any eggs they find.

The application code is about 200 lines of Python, 100 lines of which is UI-related, and you can check it out at this GitHub repo. You upload an image, the app calls Rekognition using the AWS SDK for Python (Boto3), checks the response, and draws some boxes around any eggs that it finds.

Here’s an example of code that handles regular DetectLabels requests.

response = rekognition.detect_labels(
    Image={"Bytes": image_bytes},
    MaxLabels=30,
    MinConfidence=30.0,
)

Generating test images

I needed images with scenes where Easter eggs would be unexpected. I used an image generator to create 19 images: a messy desk with an egg tucked next to the monitor, a toy box with a painted Easter egg between two teddy bears, a picnic spread with a couple eggs in between the sandwiches.

Then I generated 18 images with no eggs at all, but similar to the other scenes. That gave me a relatively balanced dataset to start with.

Round 1: DetectLabels

I wrote a batch test script (also in the GitHub repo) that ran every image I had through DetectLabels and checked whether Rekognition found an egg.

The results at a 30% confidence threshold:

Metric	Score
Accuracy	75.70%
Precision	100%
Recall	52.60%

100% precision means it never hallucinated an egg where there wasn't one in the no-egg images. But 52.6% recall means it missed about half the eggs in the egg images. Imagine you're doing an Easter egg hunt, and there are 19 eggs hidden in the yard. A recall of 52.6% means you only found 10 of them.

At a stricter 70% confidence threshold, recall dropped to 36.8%, so you'd only find about 7 out of 19.

I added logging to see what objects Rekognition detected for the missed eggs. The logged objects were pretty accurate, which told me that Rekognition identified the gist of the images well but couldn't "see" the Easter eggs.

I realized the out-of-the-box API was great for detecting Easter eggs in more typical scenes, like this one.

Script output:

  ✅ 1774389521556_img.png eggs: Egg (99.9%), Easter Egg (99.1%)

DetectLabels had a harder time finding Easter eggs in less obvious scenarios or with more competing objects, like this one.

Script output:

❌ MISS 1774389716587_img.png eggs: none
↳ saw instead: Toy (98.7%), Teddy Bear (93.5%), Lego Set (69.8%), 
   Plush (53.7%), Doll (48.1%), Play Area (48.0%), Handicraft (47.7%), 
   Hedgehog (46.9%)

Round 2: Custom Labels

Custom Labels exist for situations where you need to detect specific objects in specific scenes that go beyond the capabilities of DetectLabels, like my Easter egg images. With Custom Labels, you can train a computer vision model on your own images. The model can learn to spot what you care about, even when the object is small, partially hidden, or surrounded by lots of visual noise. The benefit here is that rather than training a computer vision model from scratch on tens of thousands of images, you can build on existing capabilities by just uploading a relatively small set of training images. Then, Rekognition handles the model training and evaluation process for you.

I did this all directly in the Amazon Rekognition console, where I created a new project and uploaded my dataset of images. Rekognition automatically split my data 80/20 for training and testing.

I created my custom label of "Easter egg" and drew bounding boxes around the Easter eggs in my dataset images, then hit Train.

Training took around 30 minutes. When it finished, I got a model ARN and performance metrics. Here's how the custom model did on the test dataset compared to the standard DetectLabels API:

Metric	DetectLabels (30% threshold)	Custom Labels
Precision	100%	77.80%
Recall	52.60%	75%
F1 score	(not calculated)	0.764

Recall jumped from 52.6% to 75%. This meant that the custom model was finding eggs that DetectLabels missed entirely. Precision dropped from 100% to 77.8% (more false positives), meaning it occasionally saw an egg where there wasn’t one, but I think that's a reasonable trade-off for catching 22% more of the eggs.

The F1 score is a metric that shows how well the model balances precision and recall, indicating its overall accuracy. A score of 0.764 from a dataset of 37 images is a good starting point.

Going back to the Easter egg hunt analogy, DetectLabels was the careful egg hunter who only picked up real eggs but walked past half of them. The custom label found most of the eggs but also grabbed a few eggish-looking rocks along the way in the test dataset.

Considering the fact that I only had 37 total images in the dataset, these are promising results, but there's definitely room to improve. I'd expect the model's performance to climb if I added more training data. But this experiment was for learning and my own curiosity, and that F1 score worked for me. I plugged my custom model’s ARN into my Streamlit app, and uploaded a few images. The custom model did a pretty good job of detecting Easter eggs on new images that weren’t part of the training dataset.

It also was pretty good about not registering false positives, even with temptingly bright round objects in the image.

Cost

Everything in this project fits comfortably within the AWS Free Tier credits for new accounts. Here are some more details on the pricing for training and inferencing with a custom model in the us-east-1 region:

DetectLabels (Group 2 API)

74 images × $0.001/image = $0.074
- I had 37 images, but I ran the batch analysis script twice (first checking for egg presence, then again to log the labels that were found for false negatives).

Custom Labels training:

0.52 hours × $1/hour = $0.52
- The docs note that Amazon Rekognition may run multiple compute resources in parallel, so actual billed hours can be higher than elapsed time for model training.

Custom Labels inferencing:

1.41 hours x $4/hour = $5.71

If you build this in your own account, be sure to STOP the model when you’re done inferencing to avoid accumulating further charges. In total for this project, I was billed for 85.7 inference minutes and 31 training minutes, which amounted to $6.24. This amount was deducted from my Free Tier credits. (The charges for other services in the following cost breakdown image are related to other Free Tier projects.)

What I learned, and what I'd do differently

The jump from DetectLabels to Custom Labels was the most interesting part of this project for me. With Custom Labels, you get to label your own data, train a model, evaluate its performance, and iterate. That loop (data → train → evaluate → improve) is the same loop behind every ML system. Custom Labels just makes it accessible without needing to have ML experience or having to spin up your own dedicated hardware.

I also came away with a better sense of when to use what. You could send an image to one of the newer multimodal foundation models and ask, "Are there any Easter eggs in this picture?" It would probably give you a very good answer. But for a tightly-scoped detection task like this one, I think a purpose-built service is a better fit. A single API call returns predictable JSON with labels, confidence scores, and bounding box coordinates. No system prompt to write, no natural language to parse. And the whole project cost me $6.24 in Free Tier credits.

A couple things I'd change if I were starting over:

Create more images for the dataset. The docs say that most custom models need a few hundred images or less, but I only had 37. I'd aim for 50+ per class (Easter egg and no Easter egg). I'd also set up a script to generate text for image prompts and call an image generating API to quickly create a bunch of training and test images.
Test with real photos, not just AI-generated ones. Generated images have a certain look to them. Real phone photos with unexpected lighting and odd angles would be a tougher test.

Try it yourself

The full code and installation directions are on GitHub here.

If you want to skip the training and just play with DetectLabels, the standard mode works immediately. Upload a photo of your breakfast and see what happens. 🍳

If you want more ideas for Free Tier projects, let me know in the comments!

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Esin Saribudak — Tue, 23 Dec 2025 18:09:01 +0000

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DEV Community: Esin Saribudak

How I trained a computer vision model on the AWS Free Tier

The idea

What I built

Generating test images

Round 1: DetectLabels

Round 2: Custom Labels

Cost

What I learned, and what I'd do differently

Try it yourself

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