Otsu Threshold | 555Tools — Online Tools for FPGA & Algorithm Engineers

Image AlgorithmsTool Introduction

Otsu's method is the classic global automatic thresholding algorithm: iterates over all possible thresholds t, computes between-class variance of foreground and background, and selects the t with maximum variance as optimal threshold. Ideal for images with bimodal histograms.

Key Formula / Principle

1. Compute 256-bin gray histogram
2. Iterate t: σ²_B(t) = wB·wF·(mB−mF)²
3. t* = argmax σ²_B(t)
4. Binarize: pixel > t* → 255, else → 0

Data Processed Locally|All computations run in your browser. Images, formulas, state machine definitions, and any other input data are never sent to any server.

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