Image stitching

Image stitching or photo stitching is the process of combining multiple photographic images with overlapping fields of view to produce a segmented panorama or high-resolution image. Commonly used in photography, surveying, GIS, and drone surveillance, image stitching is a fundamental technique in digital image processing.

Overview

The primary objective of image stitching is to combine multiple images in such a way that the resulting image appears seamless. This process involves several steps, including image registration, calibration, alignment, and blending. Image stitching is widely used not only in professional photography and cinematography but also in medical imaging, particularly in teleradiology and microscopy.

Techniques

Image Registration

The first step in image stitching is image registration, where images are spatially aligned by matching features from the overlapping areas. This involves detecting feature points or keypoints in each image and finding corresponding pairs between images.

Calibration

Calibration is crucial for correcting lens distortion and aligning images from different viewpoints. This process uses camera parameters to adjust and warp images, ensuring a uniform appearance across the stitched panorama.

Alignment

Once images are registered and calibrated, they are aligned based on the matched feature points. Alignment algorithms, such as Homography or Bundle Adjustment, are used to estimate the best possible placement of images relative to each other.

Blending

The final step is blending, where the aligned images are merged. Blending algorithms aim to minimize visible seams, color mismatches, and exposure differences. Techniques like Multi-band blending and Poisson blending are commonly used for this purpose.

Applications

Image stitching has a wide range of applications across various fields:

• In Photography, it allows for the creation of panoramic images.
• In Surveying and GIS, it is used to create large-scale maps and aerial photographs.
• In Medical Imaging, particularly in teleradiology and microscopy, it helps in creating a comprehensive view from partial images.
• In Video Stitching, it enables the production of 360-degree videos for virtual reality experiences.

Software

Several software tools are available for image stitching, ranging from professional applications like Adobe Photoshop to specialized software such as PTGui and Hugin. Open-source options, such as OpenCV, also provide libraries for developers to implement custom image stitching solutions.

Challenges

Despite advancements in technology, image stitching faces several challenges, including handling moving objects within the scene, dealing with varying exposures and lighting conditions, and correcting parallax errors. Ongoing research in computer vision and digital image processing continues to address these issues.

See Also

• Panoramic photography
• Computer vision
• Digital image processing