EAST Detects Text in One Shot

EAST predicts word boxes and their angles straight from pixels, so tilted and long lines come out in one forward pass.

EAST paints a text score map then regresses a rotated box with angle 0.52 radians, keeping the tilted word that straight boxes cut

Why Does This Exist?

Shop signs tilt and receipts run long. Axis-aligned detectors either clip letters or swallow neighbours, and multi-stage text pipelines were slow.

EAST predicts dense score and geometry maps in one pass. It specializes text detection, borrows box logic from object detection, and feeds clean crops to optical character recognition.

Think of It Like This

Tracing a tilted label with a ruler

You lay tracing paper over a tilted jar label, shade where ink sits, then draw one rotated rectangle around the shading with a protractor angle.

It fails on curved bottles. One straight rotated edge cannot hug letters that bend around the glass.

How It Actually Works

For each pixel, predict score $p$ for text presence, where $p$ near 1 means text. Where $p$ is high, regress distances to four box edges plus angle $\theta$ , where $\theta$ is box rotation in radians. A pixel with $p = 0.87$ and $\theta = 0.52$ votes a box tilted about 30 degrees, since $0.52 \times 180 / \pi \approx 29.8$ .

Worked example

A tilted word returns $p = 0.87$ above threshold 0.8, with edge distances $[12, 40, 8, 8]$ and $\theta = 0.52$ . The box corners rotate by 0.52 radians and enclose all letters. A straight box on the same pixels cuts the last letter and scores IoU 0.61 versus 0.89 for the rotated fit. The 0.28 gap is pure angle.

Watch Out For

Merging nearby lines into one quadrilateral

Close receipt lines join on low-resolution maps. The symptom is one tall box covering two lines. Raise the score threshold and shrink the geometry field near line gaps instead of lowering NMS alone.

The Quick Version

EAST outputs a score map plus rotated geometry per pixel in one pass.
Fixture angle 0.52 radians tilts the box about 30 degrees to fit the word.
Rotated IoU 0.89 beats straight 0.61 by 0.28 on tilted text.
Long and tilted lines work well, curved text does not.
Tune score threshold to stop line merging before touching NMS.