Assembleur d'Images

Image stitching is the process of combining multiple images into a single larger image. The simplest form is concatenation -- placing images side by side (horizontal) or stacked (vertical) with no overlap. This is useful for creating panoramic views from sequential photos, combining screenshots into a single long image for documentation, or creating before/after comparison images. The Canvas API handles this by creating a canvas large enough to contain all images, then drawing each image at its calculated position.

For horizontal stitching, the canvas width is the sum of all image widths (plus spacing), and the canvas height is the maximum image height. Images shorter than the maximum height can be top-aligned, center-aligned, or bottom-aligned. For vertical stitching, the canvas height is the sum of all heights, and the width is the maximum image width. Grid stitching arranges images in rows and columns -- the canvas dimensions are determined by the number of columns, the maximum image width per column, and the maximum image height per row.

Professional panorama stitching (like Photoshop's Photomerge) uses feature matching to find overlapping areas between photos and blend them seamlessly. This requires complex algorithms (SIFT, SURF, or ORB feature detection) that are computationally intensive and not practical in a browser. Our tool focuses on concatenation-style stitching, which is simpler but covers the most common use cases: sequential screenshots, side-by-side comparisons, and photo collages.

Documentation and tutorials often require stitching multiple screenshots into a single image to show a step-by-step process. Vertical stitching is ideal for this -- each screenshot is placed below the previous one, creating a single scrollable image. This is easier to share and view than multiple separate images. Adding spacing between images helps visually separate the steps.

Before/after comparisons use side-by-side (horizontal) stitching to show the difference between two versions of an image. This is common in photo editing tutorials, web design showcases, and product comparisons. For equal-width comparisons, images can be resized to the same width before stitching. Grid stitching is used for photo collages, contact sheets, and image galleries -- a 3×3 grid of product photos, for example, creates a single image that's easier to share than 9 separate files.