AstraAI

Computer vision · detection

Draw a box around it

In the curriculum:Computer visionSee the map →
🎓 School maths · Years 5–6Coordinates & position — Find the min/max coordinates of a shape to bound it.Maths by year →

The Case. When a phone camera puts a little box around a face, that's object detection. Once we know which pixels are the ball, can we box it?

Your tools. numpy finds the first and last row and column where the ball appears — that's the box.

Investigate. Press Run. A yellow box snaps around the object, just like a real detector.

  • The box is just min & max positions of the ‘ball’ pixels.
  • Move the ball in the code (change the 24 and 30) — the box follows it.
your_code.py
Starting Python…
The Reveal

Starting Python… (first time only — a few seconds)

🗒️ Detective's notes

Bundles your findings, chart and code into one PDF you can keep, print or hand in.

🧩 How this code works

The tools it uses

  • NumPy — a row of boxes that holds numbers, so you can do maths to all of them at once.
  • Matplotlib — your crayon box — it turns numbers into charts and pictures.

What this one does

  • • It shows an image made of numbers.

How to read it, top to bottom

  1. 1. Import — bring in the tools (listed above).
  2. 2. The data — the lists and numbers near the top. These are the bits you change.
  3. 3. The work — a little maths, or a loop that repeats a step.
  4. 4. Show it — print(...) writes words; plt.show() draws the picture.

Use it for your own problems

  • Change the numbers at the top and press Run — nothing breaks, so experiment!
  • Ask your own version of the question — swap in your family, your scores, your week.
  • The same tools work on any numbers — that's the superpower you're learning.
Need a hint?

np.any(mask, axis=1) is True for every row that contains part of the ball. The first and last True are the box edges.