Merging Images: Before/After Comparisons and Collages
Merging Images: Before/After Comparisons and Collages
Merging combines multiple separate images into a single composite — stacked vertically or arranged horizontally. The result is one image file that contains all the source images in sequence. This is useful for comparisons, collages, and layouts where a single image is more practical than multiple files.
When to Merge Images
Before/after comparisons. Stack two images vertically (before on top, after on bottom) or horizontally (before on left, after on right) to show a transformation. This is common for editing showcases, renovation photos, and product demonstrations.
Photo collages. Combine several photos into a single shareable image. A trip collage, a family photo collection, or a product gallery becomes one file that is easy to post or email.
Contact sheets. Arrange a set of images in a grid-like layout for quick visual reference. Photographers use these to review a shoot; designers use them to present options to clients.
Scanned document pages. If you scanned pages individually and need them as a single image rather than a PDF, merging produces a long vertical strip of all pages in sequence.
Vertical vs Horizontal Merging
Vertical merging stacks images top to bottom. The composite width matches the widest image; narrower images are aligned (left, center, or right) with background color filling the gaps. This is the standard format for before/after comparisons and scanned page strips.
Horizontal merging places images side by side, left to right. The composite height matches the tallest image; shorter images are aligned (top, center, or bottom) with background color filling gaps. This works for wide panoramas, side-by-side comparisons, and banner-style layouts.
Handling Different Image Sizes
When images have different dimensions, the merge needs to decide how to align them within the composite. The alignment options (top/center/bottom for horizontal, left/center/right for vertical) control where each image sits relative to the largest image in that axis.
The background color fills any empty space around smaller images. Choose a color that blends with your images — white is the most common choice. For a seamless look, use the same background color as the page or context where the composite will be displayed.
Spacing and Background
Spacing controls the gap between images. Zero spacing produces a seamless join where images touch directly. Small spacing (5-20 pixels) creates visual separation between images. Larger spacing produces a grid-like layout with clear borders between each image.
Background color fills the areas between and around images when spacing is used or when images have different sizes. White is standard; black creates a gallery-like presentation; matching a brand color creates a cohesive feel.
Limitations
The merge arranges images in a single row (horizontal) or single column (vertical). It does not create multi-row grid layouts — for a 3x3 grid, you would need a more advanced layout tool. The images are merged in upload order; to change the sequence, remove and re-upload in the desired order.
The output is always PNG, which preserves full quality and supports any background color. If you need a JPG output, convert the merged PNG using the Image Converter.
Try the Merge Images tool to create composites and collages.