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Haar-like features

The code behind the picture

Follow the lesson’s implementation, one code cell at a time.

Choose a language and read the cells in order. These are small teaching examples; the visual lesson runs separately.

Follow the calculation

Same inputs · Same operation · Same result

3 teaching cells · Python standard library · Read-only

  1. 1. Prepare the inputs

    Use these small, explicit inputs to follow the calculation.

    import json

positive = [8, 8, 8, 8]
negative = [2, 2, 2, 2]
threshold = 20

  2. 2. Compare rectangular sums

    This tiny Haar-like contrast example subtracts two equal-area region sums and applies a demonstration cutoff. It is not a trained detector or the full lesson’s normalized feature score.

    response = sum(positive) - sum(negative)
result = {"response": response, "pass": abs(response) >= threshold}

  3. 3. Inspect the result

    Print the result as JSON so both languages use the same output format.

    print(json.dumps(result))

Expected result

Running the three cells in order produces this result in either language.

{
  "response": 24,
  "pass": true
}