Paper Digit Reader
MNIST CNN 99.0% test accuracy

Live computer vision

Hold up a number.
We’ll read it.

Show the camera one white sheet with a single handwritten digit. OpenCV finds the page and your CNN recognizes the number.

Detected digit —
Waiting for camera

Frames are processed only while this page is open.

5

Camera preview will appear here

Offline
Detected —
Ready to start
— ms

Use a dark marker and keep all four paper corners visible.

Live diagnostics

See where the pipeline stops

1
Camera frame

Waiting for camera

WAIT
2
Paper contour

Not checked

WAIT
3
Digit extraction

Not checked

WAIT
4
CNN prediction

Not checked

WAIT
Paper edge detection output
Edge mapNo frame
Perspective-corrected paper
Warped paperExpected: complete flat page
Thresholded paper and digit
ThresholdWhite should be digit only
Final 28 by 28 CNN input
CNN input28×28 white on black
Current diagnosis Start the camera to collect diagnostics.
Raw diagnostic data 
No diagnostic response yet.
01
One digit

Write a large number from 0 to 9.

02
Clear contrast

Use dark ink on clean white paper.

03
Show the edges

Keep the complete page inside the frame.