# Image Otsu Threshold

Apply Otsu threshold operation to automatically determine optimal threshold value using Otsu's algorithm

> Canonical page: https://elysiatools.com/en/tools/image-otsu-threshold

- **Category:** Design

- **Keywords:** image, otsu, threshold, automatic, optimal, binary, binarization, histogram

## Overview

The Image Otsu Threshold tool automatically calculates the optimal threshold for your images using Otsu's algorithm, converting them into high-contrast binary files. By analyzing the image histogram, it effectively separates foreground objects from the background, making it an essential utility for image processing and computer vision preparation.

## Inputs

- **Image File** (file): Select an image file...
- **Convert to Greyscale First** (checkbox): If checked, the image will be converted to greyscale before calculating the threshold

## When to use

- When you need to isolate objects from a background for document scanning or OCR preparation.
- When you want to convert color images into clean, black-and-white binary formats automatically.
- When manual thresholding fails to provide a clear separation between image features and noise.

## How it works

- Upload your image file in a supported format like PNG, JPEG, or TIFF.
- Choose whether to convert the image to greyscale first to ensure the algorithm processes luminance data accurately.
- Click the process button to let the tool calculate the optimal threshold value using the Otsu method.
- Download your newly generated binary image file.

## Use cases

- Preparing scanned documents for text recognition by removing background noise.
- Isolating specific shapes or objects in medical or industrial imaging.
- Creating high-contrast stencils or masks for graphic design projects.

## Frequently asked questions

### What is Otsu's method?

Otsu's method is an algorithm that automatically finds the optimal threshold value by minimizing the intra-class variance of the black and white pixels.

### Do I need to set a threshold value manually?

No, this tool is designed to calculate the optimal threshold automatically based on the image's histogram.

### Which image formats are supported?

You can upload JPEG, PNG, WebP, GIF, BMP, and TIFF files.

### Why should I use the greyscale option?

Converting to greyscale simplifies the image data to intensity levels, which allows the Otsu algorithm to perform a more accurate binarization.

### Is there a file size limit?

Yes, the maximum file size for uploads is 10 MB.

## Related tools

- [Image Masking Effect](https://elysiatools.com/en/tools/image-add-masking): Apply masking effects to images using shapes, gradients, or custom masks for creative compositions
- [Image Binary Converter](https://elysiatools.com/en/tools/image-binary): Convert images to binary (black and white) with customizable threshold and options
- [Image Boolean AND](https://elysiatools.com/en/tools/image-boolean-and): Apply bitwise AND operation between two images to create intersection mask
- [Image Boolean NOT](https://elysiatools.com/en/tools/image-boolean-not): Apply bitwise NOT operation to invert all pixel values in an image
- [Image Boolean OR](https://elysiatools.com/en/tools/image-boolean-or): Apply bitwise OR operation between two images to create union mask
- [Image Boolean XOR](https://elysiatools.com/en/tools/image-boolean-xor): Apply bitwise XOR operation between two images to create difference mask
- [Image Morphological Closing](https://elysiatools.com/en/tools/image-close): Apply morphological closing operation (dilation followed by erosion) to fill small holes and connect nearby objects
- [Image Dilate](https://elysiatools.com/en/tools/image-dilate): Apply dilation morphological operation to expand foreground objects in binary images

## Samples

- [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion
- [Web Image Processing TypeScript Samples](https://elysiatools.com/en/samples/web-image-processing-typescript): Web TypeScript image processing examples including image read/save, scaling, and format conversion
- [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion
- [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion

## Related content

- [Binary Image Thresholding, Morphology, and Mask Tools](https://elysiatools.com/en/hubs/binary-image-thresholding-and-morphology): Turn images into binary masks, compare threshold methods, repair foreground shapes, and combine masks with morphological and Boolean operations.