Scale Invariant Feature Transform (SIFT) Single File Library

The Scale Invariant Feature Transform (SIFT) algorithm has been a cornerstone in computer vision for tasks like feature detection, object recognition, and image stitching. With its patents now expired, SIFT is freely available for use in any project, making it an essential tool for developers and researchers alike.

What is SIFT?

SIFT is a feature detection algorithm developed to identify and describe local features in images. It is particularly powerful because it is:

* Scale-Invariant: Features can be detected regardless of the scale of the image.
* Rotation-Invariant: Features remain consistent even when the image is rotated.
* Robust: SIFT is effective in detecting features even in noisy images or under partial occlusion.

The algorithm works by identifying keypoints in the image—specific, distinct locations like corners or edges—and then computing a descriptor for each keypoint. This descriptor is a compact representation of the local image structure around the keypoint, making it easier to match features between images.

Key applications of SIFT include:

* Image Stitching: Automatically combining overlapping images to create panoramas.
* Object Recognition: Identifying objects in images by matching features to a database.
* 3D Reconstruction: Extracting depth and structure from multiple images.

​About the jo_sift.h Library

This single-file header library, jo_sift.h, offers a minimal implementation of SIFT in plain C. Designed for simplicity, it’s easy to integrate and doesn’t rely on any external dependencies, following the same philosophy as other single-file libraries on my website.

​Key Features

* Header-Only Design: As a single-file header library, jo_sift.h is easy to include in any project. No separate compilation or complex linking is required.
* Patent-Free: With SIFT’s patents expired, this library is freely usable for both personal and commercial applications.

Example Usage

Below is an example of how to use the library:

Detecting Keypoints

Matching Keypoints

The Initial Release

jo_sift.h
File Size:	38 kb
File Type:	h

Download File

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