Combine Images (Photo Stitching)

Combining draws each photo onto one new canvas with drawImage. The alignment rule differs by mode. Horizontal takes the first photo's height as the baseline and rescales every other photo's width to match that height, keeping aspect ratio, then lays them side by side. Vertical does the opposite — it matches the first photo's width and scales each height proportionally. Grid uses the first photo's size as one cell, then places each photo centered at the largest size that fits inside the cell without cropping (contain-fit). So putting your most representative aspect ratio first affects the result quality. Gap and background color fill the empty space between/around cells.

The output is ultimately a single browser canvas, and canvases cap the maximum pixels per side. This tool validates against a safety-margin cap of 16,000px. For horizontal/vertical the stitched cumulative length, and for grid the columns×cell size, must stay under that value — otherwise combining stops and shows a warning with the projected dimensions (computed directly in code). Real browser limits are reportedly ~16,384px on Chrome/Safari and ~11,000px on Firefox, so 16,000 is a conservative line below those. If you hit the cap, reduce the photo count, or resize each photo smaller first, then combine.

The default mode is vertical (caption stitch). Stitching several chat/messenger screenshots into one image is the most common use, so it opens at vertical + gap 0px and joins seamlessly out of the box. Gap is 0-80px (2px steps) of spacing between photos, and that empty space — plus any leftover area in grid cells smaller than the photo — is filled with the background color. A white background with gap 0 looks clean for caption stitches, while a small gap with a gray or white background separates product shots nicely. Order is changed with the ↑/↓ buttons in the file list and updates the preview instantly; since horizontal and vertical modes align to the first photo, putting your most representative aspect ratio at position 1 makes the rest scale to it for a stable result. In grid mode each photo is contain-fit and centered inside its cell, so mixing different aspect ratios pads with background instead of cropping. Output is JPG (quality 0.92) or PNG (lossless): JPG keeps photo-heavy stitches small, while PNG is better for captures where text and diagrams must stay crisp. Pressing combine downloads exactly what the preview shows as one image.