When computers see
Ship and explain the 3x3 plus-sign classifier
Page 8 packages proved vs unproved evidence so another engineer can run, trust, or reject the 3×3 plus-sign image classifier.
1Learn the idea
Read
Assemble the ship record
A shippable lab artifact includes: how to run it, the metric result (accuracy on a fixed four-image set; feature activations printed), the failure you can still reproduce (overfitting to one plus orientation, or leaking test grids into template design), the security gate for claiming 'computer vision' production readiness from 3×3 toys, and a rollback note. The user decision it supports remains: classify tiny binary images as plus vs not-plus with inspectable features.
Read
Freeze the evidence
report={'clean_accuracy':1.0,'flip_accuracy':0.89,'threshold':4,'limitations':['rotation','larger images']}
assert report['clean_accuracy']>=.9
print(report)
Expected evidence: stage evidence for mastery ship. Store this beside the fixture version so scores remain meaningful after content changes in computer-sees.
Read
Explain limits without apology
State operating limits for the 3x3 plus-sign classifier in plain language: fixture size, offline vs live dependencies, and what would require a new eval set. Shipping computer-sees is honest scoping, not maximal confidence language.
Read
Lab notebook: proved vs unproved
Fill this table in your notes for the 3x3 plus-sign classifier:
- Proved on
plus, blank, and distractor 3×3 grids: … - Unproved beyond the fixture: …
- Metric that blocks release: accuracy on a fixed four-image set; feature activations printed
- Failure still reproducible: overfitting to one plus orientation, or leaking test grids into template design
- Security gate: claiming 'computer vision' production readiness from 3×3 toys
- Rollback: …
Ship the narrative only when the unproved list is honest. Reviewers trust narrow claims that support classify tiny binary images as plus vs not-plus with inspectable features more than maximal language that collapses under the first production oddity.
Read
Worked judgment
Hand your ship note to a peer and ask them to recreate a proved/unproved ship note with rollback without watching you type. If they cannot, your evidence is still tribal knowledge. Tighten the run command and the metric line until a stranger can validate the 3x3 plus-sign classifier against plus, blank, and distractor 3×3 grids.
Read
Why this stage matters for the 3x3 plus-sign classifier
At the mastery and shipping stage for computer-sees, the job is narrower than finishing a product demo. You are creating one progressive evidence piece about plus, blank, and distractor 3×3 grids that later pages inherit without redefining success. Keep that fixture small enough to inspect by hand, keep outputs copy-pasteable as text, and refuse to narrate this baseline as if it were a production SLA: pixel-sum threshold accuracy on the same four images.
For this page specifically, success looks like a proved/unproved ship note with rollback while still centering the user decision to classify tiny binary images as plus vs not-plus with inspectable features. If you cannot point to a file, command, or assertion that proves that for the 3x3 plus-sign classifier, stay on this page instead of advancing.
Glossary: computer vision · Glossary: convolutional neural network
Go deeper
Before you start
Why this matters
List two things this chapter proved on the fixture and two things it did not prove about the 3x3 plus-sign classifier. If you cannot name the gaps, you are not ready to ship the narrative—even if the code runs.
In the wild
See how this idea shows up as a product and a company — then come back to the lesson. Skills transfer across vendors.
Related lessons
Check your understanding
Page assessment
Answer from memory. Completion is saved from this evidence, not from opening the next page.
All responses are required.