# Binary Image Thresholding, Morphology, and Mask Tools

Turn images into binary masks, compare threshold methods, repair foreground shapes, and combine masks with morphological and Boolean operations.

> Canonical page: https://elysiatools.com/en/hubs/binary-image-thresholding-and-morphology

- **Keywords:** binary image tools, image thresholding, Otsu threshold, adaptive threshold, image morphology, binary mask operations, erosion and dilation, computer vision preprocessing

## Frequently asked questions

### Which threshold method should I choose?

Use a fixed threshold when lighting and contrast are consistent, Otsu when foreground and background form distinct intensity groups, and adaptive thresholding when illumination varies across the image.

### What is the difference between opening and closing?

Opening applies erosion then dilation to remove small bright noise and separate narrow connections. Closing applies dilation then erosion to fill small holes and bridge nearby foreground regions.

### When should I use erosion or dilation directly?

Use erosion to shrink foreground regions or remove thin protrusions. Use dilation to expand regions, strengthen strokes, or close small gaps before another operation.

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